// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "pdf/pdfium/pdfium_engine.h"

#include <math.h>
#include <stddef.h>
#include <stdint.h>

#include <algorithm>
#include <limits>
#include <memory>
#include <set>
#include <string>
#include <utility>

#include "arkweb/build/features/features.h"
#include "base/auto_reset.h"
#include "base/check_op.h"
#include "base/compiler_specific.h"
#include "base/containers/contains.h"
#include "base/containers/flat_map.h"
#include "base/containers/span.h"
#include "base/dcheck_is_on.h"
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/i18n/rtl.h"
#include "base/location.h"
#include "base/metrics/histogram_functions.h"
#include "base/notimplemented.h"
#include "base/notreached.h"
#include "base/numerics/safe_conversions.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/time.h"
#include "base/types/optional_util.h"
#include "build/build_config.h"
#include "components/shared_highlighting/core/common/fragment_directives_constants.h"
#include "gin/array_buffer.h"
#include "gin/public/gin_embedders.h"
#include "gin/public/isolate_holder.h"
#include "gin/public/v8_platform.h"
#include "pdf/accessibility_structs.h"
#include "pdf/buildflags.h"
#include "pdf/draw_utils/coordinates.h"
#include "pdf/draw_utils/shadow.h"
#include "pdf/input_utils.h"
#include "pdf/loader/document_loader_impl.h"
#include "pdf/loader/url_loader.h"
#include "pdf/loader/url_loader_wrapper_impl.h"
#include "pdf/page_character_index.h"
#include "pdf/pdf_accessibility_constants.h"
#include "pdf/pdf_caret.h"
#include "pdf/pdf_features.h"
#include "pdf/pdf_transform.h"
#include "pdf/pdfium/pdfium_api_string_buffer_adapter.h"
#include "pdf/pdfium/pdfium_api_wrappers.h"
#include "pdf/pdfium/pdfium_document.h"
#include "pdf/pdfium/pdfium_document_metadata.h"
#include "pdf/pdfium/pdfium_mem_buffer_file_write.h"
#include "pdf/pdfium/pdfium_page.h"
#include "pdf/pdfium/pdfium_permissions.h"
#include "pdf/pdfium/pdfium_text_fragment_finder.h"
#include "pdf/pdfium/pdfium_unsupported_features.h"
#include "pdf/region_data.h"
#include "printing/mojom/print.mojom-shared.h"
#include "printing/units.h"
#include "third_party/blink/public/common/input/web_input_event.h"
#include "third_party/blink/public/common/input/web_keyboard_event.h"
#include "third_party/blink/public/common/input/web_mouse_event.h"
#include "third_party/blink/public/common/input/web_pointer_properties.h"
#include "third_party/blink/public/common/input/web_touch_event.h"
#include "third_party/blink/public/common/input/web_touch_point.h"
#include "third_party/blink/public/web/web_print_params.h"
#include "third_party/pdfium/public/cpp/fpdf_scopers.h"
#include "third_party/pdfium/public/fpdf_annot.h"
#include "third_party/pdfium/public/fpdf_attachment.h"
#include "third_party/pdfium/public/fpdf_catalog.h"
#include "third_party/pdfium/public/fpdf_ext.h"
#include "third_party/pdfium/public/fpdf_fwlevent.h"
#include "third_party/pdfium/public/fpdf_ppo.h"
#include "third_party/pdfium/public/fpdf_searchex.h"
#include "third_party/pdfium/public/fpdfview.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/base/cursor/mojom/cursor_type.mojom-shared.h"
#include "ui/base/window_open_disposition_utils.h"
#include "ui/events/keycodes/keyboard_codes.h"
#include "ui/gfx/geometry/insets.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/point_conversions.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_conversions.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/geometry/vector2d.h"
#include "ui/gfx/geometry/vector2d_conversions.h"
#include "v8/include/v8.h"

#if defined(PDF_ENABLE_XFA)
#include "gin/public/cppgc.h"
#endif

#if BUILDFLAG(ENABLE_PDF_INK2)
#include "pdf/pdf_ink_metrics_handler.h"
#include "pdf/pdfium/pdfium_ink_reader.h"
#include "pdf/pdfium/pdfium_ink_transform.h"
#include "pdf/pdfium/pdfium_ink_writer.h"
#include "third_party/ink/src/ink/strokes/stroke.h"
#endif

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
#include "pdf/pdfium/pdfium_on_demand_searchifier.h"
#include "ui/accessibility/ax_features.mojom-features.h"
#endif

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
#include "pdf/pdfium/pdfium_font_linux.h"
#endif

#if BUILDFLAG(IS_WIN)
#include "pdf/pdfium/pdfium_font_win.h"
#endif

#if BUILDFLAG(ARKWEB_PDF)
#include "base/logging.h"
#include "arkweb/chromium_ext/pdf/pdfium/pdfium_engine_for_include.cc"
#include "third_party/ohos_ndk/includes/ohos_adapter/ohos_adapter_helper.h"
#include "base/trace_event/trace_event.h"
#endif

using printing::ConvertUnit;
using printing::ConvertUnitFloat;
using printing::kPixelsPerInch;
using printing::kPointsPerInch;

namespace chrome_pdf {

using FocusFieldType = PDFiumEngineClient::FocusFieldType;

namespace {

constexpr SkColor kHighlightColor = SkColorSetRGB(153, 193, 218);

constexpr uint32_t kPendingPageColor = 0xFFEEEEEE;

constexpr uint32_t kFormHighlightColor = 0xFFE4DD;
constexpr int32_t kFormHighlightAlpha = 100;

constexpr int kMaxPasswordTries = 3;

constexpr base::TimeDelta kTouchLongPressTimeout = base::Milliseconds(300);

// Windows has native panning capabilities. No need to use our own.
#if BUILDFLAG(IS_WIN)
constexpr bool kViewerImplementedPanning = false;
#else
constexpr bool kViewerImplementedPanning = true;
#endif

constexpr int32_t kLoadingTextVerticalOffset = 50;

// The maximum amount of time we'll spend doing a paint before we give back
// control of the thread.
constexpr base::TimeDelta kMaxProgressivePaintTime = base::Milliseconds(300);

// The maximum amount of time we'll spend doing the first paint. This is less
// than the above to keep things smooth if the user is scrolling quickly. This
// is set to 250 ms to give enough time for most PDFs to render, while avoiding
// adding too much latency to the display of the final image when the user
// stops scrolling.
// Setting a higher value has minimal benefit (scrolling at less than 4 fps will
// never be a great experience) and there is some cost, since when the user
// stops scrolling the in-progress painting has to complete or timeout before
// the final painting can start.
// The scrollbar will always be responsive since it is managed by a separate
// process.
constexpr base::TimeDelta kMaxInitialProgressivePaintTime =
    base::Milliseconds(250);
#if BUILDFLAG(ARKWEB_PDF)
constexpr char PDF_LONG_PRESS_EVENT[] = "PDF_LONG_PRESS_EVENT";
constexpr char LONG_PRESSED[] = "LONG_PRESSED";
constexpr char PDF_ENCRYPTED_DOCUMENT[] = "PDF_ENCRYPTED_DOCUMENT";
constexpr char DOCUMENT_ENCRYPTED[] = "DOCUMENT_ENCRYPTED";
constexpr char PDF_FIRST_PAINT_TIME[] = "PDF_FIRST_PAINT_TIME";
constexpr char FIRST_PAINT_TIME[] = "FIRST_PAINT_TIME";
constexpr char PDF_PAINT_VISIBLE_PAGES_TAME[] = "PDF_PAINT_VISIBLE_PAGES_TAME";
constexpr char PAINT_VISIBLE_PAGES_TAME[] = "PAINT_VISIBLE_PAGES_TAME";
// Frame rate is considered below 30fps if rendering time exceeds this threshold.
constexpr int64_t RENDER_TIME_30FPS_THRESHOLD = 33333;
#endif
FontMappingMode g_font_mapping_mode = FontMappingMode::kNoMapping;

template <class S>
bool IsAboveOrDirectlyLeftOf(const S& lhs, const S& rhs) {
  return lhs.y() < rhs.y() || (lhs.y() == rhs.y() && lhs.x() < rhs.x());
}

int CalculateCenterForZoom(int center, int length, double zoom) {
  int adjusted_center =
      static_cast<int>(center * zoom) - static_cast<int>(length * zoom / 2);
  return std::max(adjusted_center, 0);
}

// This formats a string with special 0xfffe end-of-line hyphens the same way
// as Adobe Reader. When a hyphen is encountered, the next non-CR/LF whitespace
// becomes CR+LF and the hyphen is erased. If there is no whitespace between
// two hyphens, the latter hyphen is erased and ignored.
void FormatStringWithHyphens(std::u16string* text) {
  // First pass marks all the hyphen positions.
  struct HyphenPosition {
    HyphenPosition() : position(0), next_whitespace_position(0) {}
    size_t position;
    size_t next_whitespace_position;  // 0 for none
  };
  std::vector<HyphenPosition> hyphen_positions;
  HyphenPosition current_hyphen_position;
  bool current_hyphen_position_is_valid = false;
  constexpr char16_t kPdfiumHyphenEOL = 0xfffe;

  for (size_t i = 0; i < text->size(); ++i) {
    const char16_t& current_char = (*text)[i];
    if (current_char == kPdfiumHyphenEOL) {
      if (current_hyphen_position_is_valid) {
        hyphen_positions.push_back(current_hyphen_position);
      }
      current_hyphen_position = HyphenPosition();
      current_hyphen_position.position = i;
      current_hyphen_position_is_valid = true;
    } else if (base::IsUnicodeWhitespace(current_char)) {
      if (current_hyphen_position_is_valid) {
        if (current_char != L'\r' && current_char != L'\n') {
          current_hyphen_position.next_whitespace_position = i;
        }
        hyphen_positions.push_back(current_hyphen_position);
        current_hyphen_position_is_valid = false;
      }
    }
  }
  if (current_hyphen_position_is_valid) {
    hyphen_positions.push_back(current_hyphen_position);
  }

  // With all the hyphen positions, do the search and replace.
  while (!hyphen_positions.empty()) {
    static constexpr char16_t kCr[] = {L'\r', L'\0'};
    const HyphenPosition& position = hyphen_positions.back();
    if (position.next_whitespace_position != 0) {
      (*text)[position.next_whitespace_position] = L'\n';
      text->insert(position.next_whitespace_position, kCr);
    }
    text->erase(position.position, 1);
    hyphen_positions.pop_back();
  }

  // Adobe Reader also get rid of trailing spaces right before a CRLF.
  static constexpr char16_t kSpaceCrCn[] = {L' ', L'\r', L'\n', L'\0'};
  static constexpr char16_t kCrCn[] = {L'\r', L'\n', L'\0'};
  base::ReplaceSubstringsAfterOffset(text, 0, kSpaceCrCn, kCrCn);
}

// Replace CR/LF with just LF on POSIX and Fuchsia.
void FormatStringForOS(std::u16string* text) {
#if BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  static constexpr char16_t kCr[] = {L'\r', L'\0'};
  static constexpr char16_t kBlank[] = {L'\0'};
  base::ReplaceChars(*text, kCr, kBlank, text);
#elif BUILDFLAG(IS_WIN)
  // Do nothing
#else
  NOTIMPLEMENTED();
#endif
}

// Returns true if `cur` is a character to break on.
// For double clicks, look for work breaks.
// For triple clicks, look for line breaks.
// The actual algorithm used in Blink is much more complicated, so do a simple
// approximation.
bool FindMultipleClickBoundary(bool is_double_click, uint32_t cur) {
  if (!is_double_click) {
    return cur == '\n';
  }

  // Deal with ASCII characters.
  if (base::IsAsciiAlpha(cur) || base::IsAsciiDigit(cur) || cur == '_') {
    return false;
  }
  if (cur < 128) {
    return true;
  }

  if (cur == kZeroWidthSpace) {
    return true;
  }

  return false;
}

#if defined(PDF_ENABLE_V8)
gin::IsolateHolder* g_isolate_holder = nullptr;

bool IsV8Initialized() {
  return !!g_isolate_holder;
}

void SetUpV8() {
#if defined(PDF_ENABLE_XFA)
  gin::InitializeCppgcFromV8Platform();
#endif
  if (!gin::IsolateHolder::Initialized()) {
    // TODO(crbug.com/40142415): V8 flags for the PDF Viewer need to be set up
    // as soon as the renderer process is created in the constructor of
    // `content::RenderProcessImpl`.
    const char* recommended = FPDF_GetRecommendedV8Flags();
    v8::V8::SetFlagsFromString(recommended, strlen(recommended));

    // The isolate holder is already initialized in the renderer process.
    gin::IsolateHolder::Initialize(gin::IsolateHolder::kNonStrictMode,
                                   gin::ArrayBufferAllocator::SharedInstance());
  }

  DCHECK(!g_isolate_holder);
  g_isolate_holder =
      new gin::IsolateHolder(base::SingleThreadTaskRunner::GetCurrentDefault(),
                             gin::IsolateHolder::kSingleThread,
                             gin::IsolateHolder::IsolateType::kUtility);
}

void TearDownV8() {
#if defined(PDF_ENABLE_XFA)
  gin::MaybeShutdownCppgc();
#endif

  delete g_isolate_holder;
  g_isolate_holder = nullptr;
}
#endif  // defined(PDF_ENABLE_V8)

// Returns true if the given `area` and `form_type` combination from
// PDFiumEngine::GetPointData() indicates it is a form text area.
bool IsFormTextArea(PDFiumPage::Area area, int form_type) {
  if (form_type == FPDF_FORMFIELD_UNKNOWN) {
    return false;
  }

  DCHECK_EQ(area, PDFiumPage::FormTypeToArea(form_type));
  return area == PDFiumPage::FORM_TEXT_AREA;
}

// Checks whether or not focus is in an editable form text area given the
// form field annotation flags and form type.
bool CheckIfEditableFormTextArea(int flags, int form_type) {
  if (!!(flags & FPDF_FORMFLAG_READONLY)) {
    return false;
  }
  if (form_type == FPDF_FORMFIELD_TEXTFIELD) {
    return true;
  }
  if (form_type == FPDF_FORMFIELD_COMBOBOX &&
      (!!(flags & FPDF_FORMFLAG_CHOICE_EDIT))) {
    return true;
  }
  return false;
}

bool IsLinkArea(PDFiumPage::Area area) {
  return area == PDFiumPage::WEBLINK_AREA || area == PDFiumPage::DOCLINK_AREA;
}

bool IsSelectableArea(PDFiumPage::Area area) {
  return area == PDFiumPage::TEXT_AREA || IsLinkArea(area);
}

// These values are intended for the JS to handle, and it doesn't have access
// to the PDFDEST_VIEW_* defines.
std::string ConvertViewIntToViewString(unsigned long view_int) {
  switch (view_int) {
    case PDFDEST_VIEW_XYZ:
      return "XYZ";
    case PDFDEST_VIEW_FIT:
      return "Fit";
    case PDFDEST_VIEW_FITH:
      return "FitH";
    case PDFDEST_VIEW_FITV:
      return "FitV";
    case PDFDEST_VIEW_FITR:
      return "FitR";
    case PDFDEST_VIEW_FITB:
      return "FitB";
    case PDFDEST_VIEW_FITBH:
      return "FitBH";
    case PDFDEST_VIEW_FITBV:
      return "FitBV";
    case PDFDEST_VIEW_UNKNOWN_MODE:
      return "";
    default:
      NOTREACHED();
  }
}

// Simplify to \" for searching
constexpr wchar_t kHebrewPunctuationGershayimCharacter = 0x05F4;
constexpr wchar_t kLeftDoubleQuotationMarkCharacter = 0x201C;
constexpr wchar_t kRightDoubleQuotationMarkCharacter = 0x201D;

// Simplify \' for searching
constexpr wchar_t kHebrewPunctuationGereshCharacter = 0x05F3;
constexpr wchar_t kLeftSingleQuotationMarkCharacter = 0x2018;
constexpr wchar_t kRightSingleQuotationMarkCharacter = 0x2019;

wchar_t SimplifyForSearch(wchar_t c) {
  switch (c) {
    case kHebrewPunctuationGershayimCharacter:
    case kLeftDoubleQuotationMarkCharacter:
    case kRightDoubleQuotationMarkCharacter:
      return L'\"';
    case kHebrewPunctuationGereshCharacter:
    case kLeftSingleQuotationMarkCharacter:
    case kRightSingleQuotationMarkCharacter:
      return L'\'';
    default:
      return c;
  }
}

FocusObjectType GetAnnotationFocusType(FPDF_ANNOTATION_SUBTYPE annot_type) {
  switch (annot_type) {
    case FPDF_ANNOT_LINK:
      return FocusObjectType::kLink;
    case FPDF_ANNOT_HIGHLIGHT:
      return FocusObjectType::kHighlight;
    case FPDF_ANNOT_WIDGET:
      return FocusObjectType::kTextField;
    default:
      return FocusObjectType::kNone;
  }
}

std::u16string GetAttachmentAttribute(FPDF_ATTACHMENT attachment,
                                      FPDF_BYTESTRING field) {
  return CallPDFiumWideStringBufferApi(
      base::BindRepeating(&FPDFAttachment_GetStringValue, attachment, field),
      /*check_expected_size=*/true);
}

std::u16string GetAttachmentName(FPDF_ATTACHMENT attachment) {
  return CallPDFiumWideStringBufferApi(
      base::BindRepeating(&FPDFAttachment_GetName, attachment),
      /*check_expected_size=*/true);
}

std::string GetXYZParamsString(FPDF_DEST dest, PDFiumPage* page) {
  std::string xyz_params;
  FPDF_BOOL has_x_coord;
  FPDF_BOOL has_y_coord;
  FPDF_BOOL has_zoom;
  FS_FLOAT x;
  FS_FLOAT y;
  FS_FLOAT zoom;
  if (!FPDFDest_GetLocationInPage(dest, &has_x_coord, &has_y_coord, &has_zoom,
                                  &x, &y, &zoom)) {
    return xyz_params;
  }

  // Generate a string of the parameters
  if (has_x_coord) {
    // Handle out-of-range PDF coordinates and convert PDF coordinates to screen
    // coordinates.
    xyz_params =
        base::NumberToString(page->PreProcessAndTransformInPageCoordX(x)) + ",";
  } else {
    xyz_params = "null,";
  }

  if (has_y_coord) {
    // Same conversions as x coordinates above.
    xyz_params +=
        base::NumberToString(page->PreProcessAndTransformInPageCoordY(y)) + ",";
  } else {
    xyz_params += "null,";
  }

  if (has_zoom) {
    DCHECK_NE(zoom, 0);
    xyz_params += base::NumberToString(zoom);
  } else {
    xyz_params += "null";
  }

  return xyz_params;
}

void SetXYZParamsInScreenCoords(PDFiumPage* page, base::span<float> params) {
  gfx::PointF page_coords(params[0], params[1]);
  gfx::PointF screen_coords = page->TransformPageToScreenXY(page_coords);
  params[0] = screen_coords.x();
  params[1] = screen_coords.y();
}

void SetFitRParamsInScreenCoords(PDFiumPage* page, base::span<float> params) {
  gfx::PointF point_1 =
      page->TransformPageToScreenXY(gfx::PointF(params[0], params[1]));
  gfx::PointF point_2 =
      page->TransformPageToScreenXY(gfx::PointF(params[2], params[3]));
  params[0] = point_1.x();
  params[1] = point_1.y();
  params[2] = point_2.x();
  params[3] = point_2.y();
}

// A helper function that transforms the PDF coordinates in `params` to screen
// coordinates depending on the view's fit type. `params` is an in-out
// parameter.
void ParamsTransformPageToScreen(unsigned long view_fit_type,
                                 PDFiumPage* page,
                                 base::span<float> params) {
  switch (view_fit_type) {
    case PDFDEST_VIEW_XYZ:
      SetXYZParamsInScreenCoords(page, params);
      break;
    case PDFDEST_VIEW_FIT:
    case PDFDEST_VIEW_FITB:
      // No parameters for coordinates to be transformed.
      break;
    case PDFDEST_VIEW_FITBH:
    case PDFDEST_VIEW_FITH:
      // FitH/FitBH only has 1 parameter for y coordinate.
      params[0] = page->TransformPageToScreenY(params[0]);
      break;
    case PDFDEST_VIEW_FITBV:
    case PDFDEST_VIEW_FITV:
      // FitV/FitBV only has 1 parameter for x coordinate.
      params[0] = page->TransformPageToScreenX(params[0]);
      break;
    case PDFDEST_VIEW_FITR:
      SetFitRParamsInScreenCoords(page, params);
      break;
    case PDFDEST_VIEW_UNKNOWN_MODE:
      break;
    default:
      NOTREACHED();
  }
}

#if BUILDFLAG(ENABLE_PDF_INK2)
class ScopedPageObjectDeactivator {
 public:
  explicit ScopedPageObjectDeactivator(
      std::vector<FPDF_PAGEOBJECT> page_objects)
      : page_objects_(std::move(page_objects)) {
    for (FPDF_PAGEOBJECT page_object : page_objects_) {
      bool result = FPDFPageObj_SetIsActive(page_object, /*active=*/false);
      CHECK(result);
    }
  }
  ~ScopedPageObjectDeactivator() {
    for (FPDF_PAGEOBJECT page_object : page_objects_) {
      bool result = FPDFPageObj_SetIsActive(page_object, /*active=*/true);
      CHECK(result);
    }
  }

 private:
  std::vector<FPDF_PAGEOBJECT> page_objects_;
};

#endif

}  // namespace

void InitializeSDK(bool enable_v8,
                   bool use_skia,
                   FontMappingMode font_mapping_mode) {
  FPDF_LIBRARY_CONFIG config;
  config.version = 4;
  config.m_pUserFontPaths = nullptr;
  config.m_pIsolate = nullptr;
  config.m_pPlatform = nullptr;
  config.m_v8EmbedderSlot = gin::kEmbedderPDFium;
  config.m_RendererType =
      use_skia ? FPDF_RENDERERTYPE_SKIA : FPDF_RENDERERTYPE_AGG;

#if defined(PDF_ENABLE_V8)
  if (enable_v8) {
    SetUpV8();
    config.m_pIsolate = g_isolate_holder->isolate();
    // NOTE: static_cast<> prior to assigning to (void*) is safer since it
    // will manipulate the pointer value should gin::V8Platform someday have
    // multiple base classes.
    config.m_pPlatform = static_cast<v8::Platform*>(gin::V8Platform::Get());
  }
#endif  // defined(PDF_ENABLE_V8)

  FPDF_InitLibraryWithConfig(&config);

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
  g_font_mapping_mode = font_mapping_mode;
  InitializeLinuxFontMapper();
#endif

#if BUILDFLAG(IS_WIN)
  if (font_mapping_mode == FontMappingMode::kBlink) {
    g_font_mapping_mode = font_mapping_mode;
    InitializeWindowsFontMapper();
  }
#endif

  InitializeUnsupportedFeaturesHandler();
}

void ShutdownSDK() {
  FPDF_DestroyLibrary();
#if defined(PDF_ENABLE_V8)
  if (IsV8Initialized()) {
    TearDownV8();
  }
#endif  // defined(PDF_ENABLE_V8)
}

PDFiumEngine::PDFiumEngine(PDFiumEngineClient* client,
                           PDFiumFormFiller::ScriptOption script_option)
    : client_(client),
      form_filler_(this, script_option),
      mouse_down_state_(PDFiumPage::NONSELECTABLE_AREA,
                        PDFiumPage::LinkTarget()),
      engine_creation_time_(base::TimeTicks::Now()),
      print_(this) {
#if defined(PDF_ENABLE_V8)
  if (script_option != PDFiumFormFiller::ScriptOption::kNoJavaScript) {
    DCHECK(IsV8Initialized());
  }
#endif  // defined(PDF_ENABLE_V8)

  IFSDK_PAUSE::version = 1;
  IFSDK_PAUSE::user = nullptr;
  IFSDK_PAUSE::NeedToPauseNow = Pause_NeedToPauseNow;
}

PDFiumEngine::~PDFiumEngine() {
  if (!client_->IsPrintPreview()) {
    base::UmaHistogramLongTimes("PDF.EngineLifetime",
                                base::TimeTicks::Now() - engine_creation_time_);
  }
#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
  if (searchifier_ && searchifier_->PerformedOCR()) {
    base::UmaHistogramBoolean("PDF.SearchifySuccessful2", has_searchify_text_);
  }

  // Should be reset before document is unloaded.
  searchifier_.reset();
#endif

  // Clear all the containers that can prevent unloading.
  find_results_.clear();
  selection_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)
#if BUILDFLAG(ENABLE_PDF_INK2)
  ink_stroke_data_.clear();
  stroked_pages_unload_preventers_.clear();
#endif

  for (auto& page : pages_) {
    page->Unload();
  }

  if (doc()) {
    FORM_DoDocumentAAction(form(), FPDFDOC_AACTION_WC);
  }
}

void PDFiumEngine::SetDocumentLoaderForTesting(
    std::unique_ptr<DocumentLoader> loader) {
  DCHECK(loader);
  DCHECK(!doc_loader_);
  doc_loader_ = std::move(loader);
  doc_loader_set_for_testing_ = true;
}

// static
FontMappingMode PDFiumEngine::GetFontMappingMode() {
  return g_font_mapping_mode;
}

void PDFiumEngine::PageOffsetUpdated(const gfx::Vector2d& page_offset) {
  page_offset_ = page_offset;
}

void PDFiumEngine::PluginSizeUpdated(const gfx::Size& size) {
  CancelPaints();

  plugin_size_ = size;
  CalculateVisiblePages();
  OnSelectionPositionChanged();

  if (caret_) {
    caret_->OnGeometryChanged();
  }

  if (document_pending_) {
    // This method may be called in a `blink::ScriptForbiddenScope` context,
    // which imposes certain restrictions on clients. Complete the work
    // asynchronously to avoid observable differences between this path and the
    // normal loading path.
    document_pending_ = false;
    base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
        FROM_HERE, base::BindOnce(&PDFiumEngine::FinishLoadingDocument,
                                  weak_factory_.GetWeakPtr()));
  }
}

void PDFiumEngine::ScrolledToXPosition(int position) {
  CancelPaints();

  gfx::Vector2d diff(position_.x() - position, 0);
  position_.set_x(position);
  CalculateVisiblePages();

  client_->DidScroll(diff);
  caret_rect_ += diff;
  client_->CaretChanged(caret_rect_);

  OnSelectionPositionChanged();
  if (caret_) {
    caret_->OnGeometryChanged();
  }
}

void PDFiumEngine::ScrolledToYPosition(int position) {
  CancelPaints();

  gfx::Vector2d diff(0, position_.y() - position);
  position_.set_y(position);
  CalculateVisiblePages();

  client_->DidScroll(diff);
  caret_rect_ += diff;
  client_->CaretChanged(caret_rect_);

  OnSelectionPositionChanged();
  if (caret_) {
    caret_->OnGeometryChanged();
  }
}

void PDFiumEngine::PrePaint() {
  for (auto& paint : progressive_paints_) {
    paint.set_painted(false);
  }
}

void PDFiumEngine::Paint(const gfx::Rect& rect,
                         SkBitmap& image_data,
                         std::vector<gfx::Rect>& ready,
                         std::vector<gfx::Rect>& pending) {
  gfx::Rect leftover = rect;

  // Set a timer here to check how long it takes to finish rendering and
  // painting the visible pages.
  base::TimeTicks begin_time = base::TimeTicks::Now();

  if (!first_paint_metric_reported_ && !client_->IsPrintPreview()) {
    first_paint_metric_reported_ = true;
    base::UmaHistogramMediumTimes("PDF.FirstPaintTime",
                                  begin_time - engine_creation_time_);
#if BUILDFLAG(ARKWEB_PDF)
    int64_t firstPaintTime =
        (begin_time - engine_creation_time_).ToInternalValue();
    OHOS::NWeb::OhosAdapterHelper::GetInstance()
        .GetHiSysEventAdapterInstance()
        .Write(PDF_FIRST_PAINT_TIME,
               OHOS::NWeb::HiSysEventAdapter::EventType::BEHAVIOR,
               {FIRST_PAINT_TIME, std::to_string(firstPaintTime)});
#endif
  }

  for (size_t i = 0; i < visible_pages_.size(); ++i) {
    uint32_t index = visible_pages_[i];
    // Convert the current page's rectangle to screen rectangle.  We do this
    // instead of the reverse (converting the dirty rectangle from screen to
    // PDF coordinates) because then we'd have to convert back to screen
    // coordinates, and the rounding errors sometime leave pixels dirty or even
    // move the text up or down a pixel when zoomed.
    gfx::Rect page_rect_in_screen = GetPageScreenRect(index);
    gfx::Rect dirty_in_screen =
        gfx::IntersectRects(page_rect_in_screen, leftover);
    if (dirty_in_screen.IsEmpty()) {
      continue;
    }

    // Compute the leftover dirty region. The first page may have blank space
    // above it, in which case we also need to subtract that space from the
    // dirty region.
    // If two-up view is enabled, we don't need to recompute `leftover` since
    // subtracting `leftover` with a two-up view page won't result in a
    // rectangle.
    if (layout_.options().page_spread() == DocumentLayout::PageSpread::kOneUp) {
      if (i == 0) {
        gfx::Rect blank_space_in_screen = dirty_in_screen;
        blank_space_in_screen.set_y(0);
        blank_space_in_screen.set_height(dirty_in_screen.y());
        leftover.Subtract(blank_space_in_screen);
      }

      leftover.Subtract(dirty_in_screen);
    }

    if (pages_[index]->available()) {
      std::optional<size_t> progressive_index = GetProgressiveIndex(index);
      if (progressive_index.has_value()) {
        CHECK_LT(progressive_index.value(), progressive_paints_.size());
        if (progressive_paints_[progressive_index.value()].rect() !=
            dirty_in_screen) {
          // The PDFium code can only handle one progressive paint at a time, so
          // queue this up. Previously we used to merge the rects when this
          // happened, but it made scrolling up on complex PDFs very slow since
          // there would be a damaged rect at the top (from scroll) and at the
          // bottom (from toolbar).
          pending.push_back(dirty_in_screen);
          continue;
        }
      }

      if (progressive_index.has_value()) {
        progressive_paint_timeout_ = kMaxProgressivePaintTime;
      } else {
        progressive_index = StartPaint(index, dirty_in_screen);
        progressive_paint_timeout_ = kMaxInitialProgressivePaintTime;
      }

      progressive_paints_[progressive_index.value()].set_painted(true);
      if (ContinuePaint(progressive_index.value(), image_data)) {
        FinishPaint(progressive_index.value(), image_data);
        ready.push_back(dirty_in_screen);
      } else {
        pending.push_back(dirty_in_screen);
      }
    } else {
      PaintUnavailablePage(index, dirty_in_screen, image_data);
      ready.push_back(dirty_in_screen);
    }
  }

  base::UmaHistogramMediumTimes("PDF.RenderAndPaintVisiblePagesTime",
                                base::TimeTicks::Now() - begin_time);
#if BUILDFLAG(ARKWEB_PDF)
  int64_t paintVisiblePagesTime =
      (base::TimeTicks::Now() - begin_time).ToInternalValue();
  if (paintVisiblePagesTime > RENDER_TIME_30FPS_THRESHOLD)
    OHOS::NWeb::OhosAdapterHelper::GetInstance()
        .GetHiSysEventAdapterInstance()
        .Write(PDF_PAINT_VISIBLE_PAGES_TAME,
              OHOS::NWeb::HiSysEventAdapter::EventType::BEHAVIOR,
              {PAINT_VISIBLE_PAGES_TAME, std::to_string(paintVisiblePagesTime)});
#endif
}

void PDFiumEngine::PostPaint() {
  // Remove all entries that were never painted, as they must have been merged
  // with other entries. If they are not removed, painting will never finish.
  for (const ProgressivePaint& entry : progressive_paints_) {
    if (!entry.painted()) {
      FPDF_RenderPage_Close(pages_[entry.page_index()]->GetPage());
    }
  }
  std::erase_if(progressive_paints_,
                [](const ProgressivePaint& entry) { return !entry.painted(); });
}

bool PDFiumEngine::HandleDocumentLoad(std::unique_ptr<UrlLoader> loader,
                                      const std::string& original_url) {
  LOG(INFO) << __func__ << ", PDF client start to consume.";
  password_tries_remaining_ = kMaxPasswordTries;
  process_when_pending_request_complete_ =
      base::FeatureList::IsEnabled(features::kPdfIncrementalLoading);

  if (!doc_loader_set_for_testing_) {
    doc_loader_ = std::make_unique<DocumentLoaderImpl>(this);
    if (!doc_loader_->Init(
            std::make_unique<URLLoaderWrapperImpl>(std::move(loader)),
            original_url)) {
      return false;
    }
  }
  document_ = std::make_unique<PDFiumDocument>(doc_loader_.get());

  // request initial data.
  doc_loader_->RequestData(0, 1);
  return true;
}

std::unique_ptr<URLLoaderWrapper> PDFiumEngine::CreateURLLoader() {
  return std::make_unique<URLLoaderWrapperImpl>(client_->CreateUrlLoader());
}

void PDFiumEngine::AppendPage(PDFiumEngine* engine, int index) {
  CHECK(engine);
  CHECK(PageIndexInBounds(index));

  // Unload and delete the blank page before appending.
  pages_[index]->Unload();
  pages_[index]->set_calculated_links(false);
  gfx::Size curr_page_size = GetPageSize(index);
  FPDFPage_Delete(doc(), index);
  FPDF_ImportPages(doc(), static_cast<PDFiumEngine*>(engine)->doc(), "1",
                   index);
  gfx::Size new_page_size = GetPageSize(index);
  if (curr_page_size != new_page_size) {
    DCHECK(document_loaded_);
    LoadPageInfo();
  }
  client_->Invalidate(GetPageScreenRect(index));
}

std::vector<uint8_t> PDFiumEngine::GetSaveData() {
#if BUILDFLAG(ENABLE_PDF_INK2)
  RegenerateContents();
#endif

  PDFiumMemBufferFileWrite output_file_write;
  if (!FPDF_SaveAsCopy(doc(), &output_file_write, 0)) {
    return std::vector<uint8_t>();
  }
  return output_file_write.TakeBuffer();
}

void PDFiumEngine::OnPendingRequestComplete() {
  if (!process_when_pending_request_complete_) {
    return;
  }

  if (!fpdf_availability()) {
    document_->file_access().m_FileLen = doc_loader_->GetDocumentSize();
    document_->CreateFPDFAvailability();

    // Currently engine does not deal efficiently with some non-linearized
    // files.
    // See http://code.google.com/p/chromium/issues/detail?id=59400
    // To improve user experience we download entire file for non-linearized
    // PDF.
    if (!IsLinearized()) {
      // Wait complete document.
      process_when_pending_request_complete_ = false;
      document_->ResetFPDFAvailability();
      return;
    }
  }

  if (!doc()) {
    LoadDocument();
    return;
  }

  if (pages_.empty()) {
    LoadBody();
    return;
  }

  // LoadDocument() will result in `pending_pages_` being reset so there's no
  // need to run the code below in that case.
  bool update_pages = false;
  std::vector<uint32_t> still_pending;
  for (uint32_t pending_page : pending_pages_) {
    if (CheckPageAvailable(pending_page, &still_pending)) {
      update_pages = true;
      if (IsPageVisible(pending_page)) {
        client_->Invalidate(GetPageScreenRect(pending_page));
      }
    }
  }
  pending_pages_.swap(still_pending);
  if (update_pages) {
    DCHECK(!document_loaded_);
    LoadPageInfo();
  }
}

void PDFiumEngine::OnNewDataReceived() {
  client_->DocumentLoadProgress(doc_loader_->BytesReceived(),
                                doc_loader_->GetDocumentSize());
}

void PDFiumEngine::OnDocumentComplete() {
  if (doc()) {
    return FinishLoadingDocument();
  }

  document_->file_access().m_FileLen = doc_loader_->GetDocumentSize();
  if (!fpdf_availability()) {
    document_->CreateFPDFAvailability();
    DCHECK(fpdf_availability());
  }
  LoadDocument();
}

void PDFiumEngine::OnDocumentCanceled() {
  if (visible_pages_.empty()) {
    client_->DocumentLoadFailed();
  } else {
    OnDocumentComplete();
  }
}

void PDFiumEngine::ClearTextSelection() {
  SelectionChangeInvalidator selection_invalidator(this);
  selection_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)
}

void PDFiumEngine::ExtendAndInvalidateSelectionByChar(
    const PageCharacterIndex& index) {
  CHECK(PageIndexInBounds(index.page_index));
  CHECK_GT(GetCharCount(index.page_index), 0u);

  SelectionChangeInvalidator selection_invalidator(this);
  ExtendSelectionByChar(index);
  if (caret_) {
    caret_->SetVisible(!IsSelecting());
  }
}

uint32_t PDFiumEngine::GetCharCount(uint32_t page_index) const {
  CHECK(PageIndexInBounds(page_index));
  return base::checked_cast<uint32_t>(pages_[page_index]->GetCharCount());
}

PageOrientation PDFiumEngine::GetCurrentOrientation() const {
  return layout_.options().default_page_orientation();
}

std::vector<gfx::Rect> PDFiumEngine::GetScreenRectsForCaret(
    const PageCharacterIndex& index) const {
  CHECK(PageIndexInBounds(index.page_index));
  PDFiumPage* page = pages_[index.page_index].get();

  if (page->GetCharCount() == 0 && index.char_index == 0) {
    return GetNoTextPageScreenRectsForCaret(page);
  }

  CHECK(page->IsCharIndexInBounds(index.char_index));

  PDFiumRange range(page, index.char_index, 1);
  return range.GetScreenRects(GetVisibleRect().origin(), current_zoom_,
                              GetCurrentOrientation());
}

std::optional<AccessibilityTextRunInfo> PDFiumEngine::GetTextRunInfoAt(
    const PageCharacterIndex& index) const {
  if (!PageIndexInBounds(index.page_index)) {
    return std::nullopt;
  }

  PDFiumPage* page = pages_[index.page_index].get();
  if (page->GetCharCount() == 0 ||
      !page->IsCharIndexInBounds(index.char_index)) {
    return std::nullopt;
  }

  return page->GetTextRunInfoAt(index.char_index).value();
}

void PDFiumEngine::InvalidateRect(const gfx::Rect& rect) {
  client_->Invalidate(rect);
}

bool PDFiumEngine::IsSelecting() const {
  // `selection_` can have multiple entries with all char counts set to 0, but
  // `GetSelectedText()` inserts a newline between pages. In this case, return
  // true.
  return !selection_.empty() &&
         (selection_.size() > 1 || !selection_[0].GetText().empty());
}

bool PDFiumEngine::IsSynthesizedNewline(const PageCharacterIndex& index) const {
  CHECK(PageIndexInBounds(index.page_index));
  PDFiumPage* page = pages_[index.page_index].get();
  CHECK(page->IsCharIndexInBounds(index.char_index));

  if (FPDFText_IsGenerated(page->GetTextPage(), index.char_index) != 1) {
    return false;
  }

  uint32_t char_code = page->GetCharUnicode(index.char_index);
  return char_code == '\r' || char_code == '\n';
}

bool PDFiumEngine::PageIndexInBounds(int index) const {
  return index >= 0 && index < static_cast<int>(pages_.size());
}

void PDFiumEngine::ScrollToChar(const PageCharacterIndex& index) {
  CHECK(PageIndexInBounds(index.page_index));
  PDFiumPage* page = pages_[index.page_index].get();

  if (page->GetCharCount() == 0 && index.char_index == 0) {
    ScrollToPage(index.page_index);
    return;
  }

  CHECK(page->IsCharIndexInBounds(index.char_index));

  PDFiumRange range(page, index.char_index, 1);
  ScrollToBoundingRects(range, /*force_smooth_scroll=*/false);
}

void PDFiumEngine::StartSelection(const PageCharacterIndex& index) {
  CHECK(PageIndexInBounds(index.page_index));
  CHECK_GT(GetCharCount(index.page_index), 0u);

  if (!selection_.empty()) {
    return;
  }

  selection_.push_back(
      PDFiumRange(pages_[index.page_index].get(), index.char_index, 0));
}

void PDFiumEngine::FinishLoadingDocument() {
#if BUILDFLAG(ARKWEB_PDF)
  TRACE_EVENT0("media", "PDFiumEngine::FinishLoadingDocument");
#endif
  // Note that doc_loader_->IsDocumentComplete() may not be true here if
  // called via `OnDocumentCanceled()`.
  DCHECK(doc());

  DCHECK(!document_pending_);
  if (!plugin_size_.has_value()) {
    // Don't finish loading until `plugin_size_` is initialized.
    document_pending_ = true;
    return;
  }

  LoadBody();

  FX_DOWNLOADHINTS& download_hints = document_->download_hints();
  bool need_update = false;
  for (size_t i = 0; i < pages_.size(); ++i) {
    if (pages_[i]->available()) {
      continue;
    }

    pages_[i]->MarkAvailable();
    // We still need to call IsPageAvail() even if the whole document is
    // already downloaded.
    FPDFAvail_IsPageAvail(fpdf_availability(), i, &download_hints);
    need_update = true;
    if (IsPageVisible(i)) {
      client_->Invalidate(GetPageScreenRect(i));
    }
  }

  // Transition `document_loaded_` to true after finishing any calls to
  // FPDFAvail_IsPageAvail(), since we no longer need to defer calls to this
  // function from LoadPageInfo(). Note that LoadBody() calls LoadPageInfo()
  // indirectly, so we cannot make this transition earlier.
  document_loaded_ = true;

  if (need_update) {
    LoadPageInfo();
  }

  LoadDocumentAttachmentInfoList();

  LoadDocumentMetadata();

  if (called_do_document_action_) {
    return;
  }
  called_do_document_action_ = true;

  // These can only be called now, as the JS might end up needing a page.
  FORM_DoDocumentJSAction(form());
  FORM_DoDocumentOpenAction(form());
  if (most_visible_page_ != -1) {
    FPDF_PAGE new_page = pages_[most_visible_page_]->GetPage();
    FORM_DoPageAAction(new_page, form(), FPDFPAGE_AACTION_OPEN);
  }

  client_->DocumentLoadComplete();
}

void PDFiumEngine::UnsupportedFeature(const std::string& feature) {
  client_->DocumentHasUnsupportedFeature(feature);
}

FPDF_AVAIL PDFiumEngine::fpdf_availability() const {
  return document_ ? document_->fpdf_availability() : nullptr;
}

FPDF_DOCUMENT PDFiumEngine::doc() const {
  return document_ ? document_->doc() : nullptr;
}

FPDF_FORMHANDLE PDFiumEngine::form() const {
  return document_ ? document_->form() : nullptr;
}

PDFiumPage* PDFiumEngine::GetPage(size_t index) {
  return index < pages_.size() ? pages_[index].get() : nullptr;
}

bool PDFiumEngine::IsValidLink(const std::string& url) {
  return client_->IsValidLink(url);
}

void PDFiumEngine::SetFormHighlight(bool enable_form) {
  // Restore form highlights.
  if (enable_form) {
    FPDF_SetFormFieldHighlightAlpha(form(), kFormHighlightAlpha);
    return;
  }

  // Hide form highlights.
  FPDF_SetFormFieldHighlightAlpha(form(), /*alpha=*/0);
  KillFormFocus();
}

bool PDFiumEngine::FindAndHighlightTextFragments(
    base::span<const std::string> text_fragments) {
  HighlightChangeInvalidator invalidator(this);
  PDFiumTextFragmentFinder text_fragment_finder(this);
  client_->OnNewTextFragmentsSearchStarted();
  // Caches results.
  text_fragment_highlights_ =
      text_fragment_finder.FindTextFragments(text_fragments);
  return !text_fragment_highlights_.empty();
}

void PDFiumEngine::ScrollTextFragmentIntoView() {
  ScrollToFirstTextFragment(/*force_smooth_scroll=*/true);
}

void PDFiumEngine::ScrollToFirstTextFragment(bool force_smooth_scroll) {
  CHECK(!text_fragment_highlights_.empty());
  ScrollToBoundingRects(text_fragment_highlights_[0], force_smooth_scroll);
}

void PDFiumEngine::RemoveTextFragments() {
  if (!text_fragment_highlights_.empty()) {
    HighlightChangeInvalidator invalidator(this);
    text_fragment_highlights_.clear();
  }
}

void PDFiumEngine::SearchForFragment(
    const std::u16string& term,
    int character_to_start_searching_from,
    int last_character_index_to_search,
    int page_to_search,
    AddSearchResultCallback add_result_callback) {
  SearchUsingICU(term, /*case_sensitive=*/false, /*first_search=*/false,
                 character_to_start_searching_from,
                 last_character_index_to_search, page_to_search, page_to_search,
                 std::move(add_result_callback));
}

void PDFiumEngine::SetCaretBrowsingEnabled(bool enabled) {
  CHECK(features::kPdfInk2TextHighlighting.Get());
  CHECK(!client_->IsPrintPreview());

  if (pages_.empty() || (caret_ && caret_->enabled() == enabled)) {
    return;
  }

  if (!caret_) {
    if (!enabled) {
      return;
    }
    caret_ = std::make_unique<PdfCaret>(this);
    caret_->SetVisible(has_focus_);
  }

  caret_->SetEnabled(enabled);

  if (enabled) {
    // Move the caret to the first visible text run. If there is no visible
    // text, leave the caret at its original position.
    for (auto page_index : visible_pages_) {
      std::optional<AccessibilityTextRunInfo> text_run =
          GetFirstVisibleTextRun(page_index);
      if (text_run.has_value()) {
        caret_->SetCharAndDraw({page_index, text_run->start_index});
        break;
      }
    }
  }
}

void PDFiumEngine::SetCaretBlinkInterval(base::TimeDelta interval) {
  if (caret_) {
    caret_->SetBlinkInterval(interval);
  }
}

void PDFiumEngine::ContinueFind(bool case_sensitive) {
  StartFind(current_find_text_, case_sensitive);
}

bool PDFiumEngine::HandleInputEvent(const blink::WebInputEvent& event) {
  DCHECK(!defer_page_unload_);
  defer_page_unload_ = true;
  bool rv = false;
#if BUILDFLAG(ARKWEB_PDF)
  LOG(DEBUG) << "PDFiumEngine::HandleInputEvent " << event.GetType();
#endif
  switch (event.GetType()) {
    case blink::WebInputEvent::Type::kMouseDown:
      rv = OnMouseDown(static_cast<const blink::WebMouseEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kMouseUp:
      rv = OnMouseUp(static_cast<const blink::WebMouseEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kMouseMove:
      rv = OnMouseMove(static_cast<const blink::WebMouseEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kMouseEnter:
      OnMouseEnter(static_cast<const blink::WebMouseEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kKeyDown:
      // Blink mostly sends `kRawKeyDown`, but sometimes generates `kKeyDown`,
      // such as when tabbing between frames. Pepper treats them equivalently
      // (see content/renderer/pepper/event_conversion.cc), so we will, too.
    case blink::WebInputEvent::Type::kRawKeyDown:
      rv = OnKeyDown(static_cast<const blink::WebKeyboardEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kKeyUp:
      rv = OnKeyUp(static_cast<const blink::WebKeyboardEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kChar:
      rv = OnChar(static_cast<const blink::WebKeyboardEvent&>(event));
      break;
    case blink::WebInputEvent::Type::kTouchStart: {
      KillTouchTimer();

      const auto& touch_event = static_cast<const blink::WebTouchEvent&>(event);
      if (touch_event.touches_length == 1) {
        ScheduleTouchTimer(touch_event);
      }
      break;
    }
    case blink::WebInputEvent::Type::kTouchEnd:
      KillTouchTimer();
#if BUILDFLAG(ARKWEB_PDF)
      client_->SetIsTouching(false);
#endif  // BUILDFLAG(ARKWEB_PDF)

      break;
    case blink::WebInputEvent::Type::kTouchMove:
      // TODO(dsinclair): This should allow a little bit of movement (up to the
      // touch radii) to account for finger jiggle.
      KillTouchTimer();
#if BUILDFLAG(ARKWEB_PDF)
      client_->SetIsTouching(true);
#endif  // BUILDFLAG(ARKWEB_PDF)
      break;
    default:
      break;
  }

  DCHECK(defer_page_unload_);
  defer_page_unload_ = false;

  // Store the pages to unload away because the act of unloading pages can cause
  // there to be more pages to unload. We leave those extra pages to be unloaded
  // on the next go around.
  std::vector<int> pages_to_unload;
  std::swap(pages_to_unload, deferred_page_unloads_);
  for (int page_index : pages_to_unload) {
    pages_[page_index]->Unload();
  }

  return rv;
}

void PDFiumEngine::PrintBegin() {
  FORM_DoDocumentAAction(form(), FPDFDOC_AACTION_WP);
#if BUILDFLAG(ENABLE_PDF_INK2)
  RegenerateContents();
#endif
}

std::vector<uint8_t> PDFiumEngine::PrintPages(
    base::span<const int> page_indices,
    const blink::WebPrintParams& print_params) {
  if (page_indices.empty()) {
    return std::vector<uint8_t>();
  }

  return print_params.rasterize_pdf
             ? PrintPagesAsRasterPdf(page_indices, print_params)
             : PrintPagesAsPdf(page_indices, print_params);
}

std::vector<uint8_t> PDFiumEngine::PrintPagesAsRasterPdf(
    base::span<const int> page_indices,
    const blink::WebPrintParams& print_params) {
  DCHECK(HasPermission(DocumentPermission::kPrintLowQuality));

  // If document is not downloaded yet, disable printing.
  if (doc() && !doc_loader_->IsDocumentComplete()) {
    return std::vector<uint8_t>();
  }

  KillFormFocus();

  return print_.PrintPagesAsPdf(page_indices, print_params);
}

std::vector<uint8_t> PDFiumEngine::PrintPagesAsPdf(
    base::span<const int> page_indices,
    const blink::WebPrintParams& print_params) {
  DCHECK(HasPermission(DocumentPermission::kPrintHighQuality));
  DCHECK(doc());

  KillFormFocus();

  for (int page_index : page_indices) {
    pages_[page_index]->GetPage();
    if (!IsPageVisible(page_index)) {
      pages_[page_index]->Unload();
    }
  }

  return print_.PrintPagesAsPdf(page_indices, print_params);
}

void PDFiumEngine::KillFormFocus() {
  if (focus_field_type_ == FocusFieldType::kNoFocus) {
    return;
  }

  FORM_ForceToKillFocus(form());
  SetFieldFocus(FocusFieldType::kNoFocus);
}

void PDFiumEngine::UpdateFocus(bool has_focus) {
  has_focus_ = has_focus;
  bool can_focus = !IsReadOnly();
#if BUILDFLAG(ENABLE_PDF_INK2)
  can_focus = can_focus && !client_->IsInAnnotationMode();
#endif  // BUILDFLAG(ENABLE_PDF_INK2)
  base::AutoReset<bool> updating_focus_guard(&updating_focus_, true);
  if (has_focus && can_focus) {
    UpdateFocusElementType(last_focused_element_type_);
    if (focus_element_type_ == FocusElementType::kPage &&
        PageIndexInBounds(last_focused_page_) &&
        last_focused_annot_index_ != -1) {
      ScopedFPDFAnnotation last_focused_annot(FPDFPage_GetAnnot(
          pages_[last_focused_page_]->GetPage(), last_focused_annot_index_));
      if (last_focused_annot) {
        FPDF_BOOL ret = FORM_SetFocusedAnnot(form(), last_focused_annot.get());
        DCHECK(ret);
        return;
      }
    }
  } else {
    last_focused_element_type_ = focus_element_type_;
    if (focus_element_type_ == FocusElementType::kDocument) {
      UpdateFocusElementType(FocusElementType::kNone);
    } else if (focus_element_type_ == FocusElementType::kPage) {
      FPDF_ANNOTATION last_focused_annot = nullptr;
      FPDF_BOOL ret = FORM_GetFocusedAnnot(form(), &last_focused_page_,
                                           &last_focused_annot);
      if (ret && PageIndexInBounds(last_focused_page_) && last_focused_annot) {
        last_focused_annot_index_ = FPDFPage_GetAnnotIndex(
            pages_[last_focused_page_]->GetPage(), last_focused_annot);
      } else {
        last_focused_annot_index_ = -1;
      }
      FPDFPage_CloseAnnot(last_focused_annot);
    }
    KillFormFocus();
    if (has_focus) {
      return;
    }
  }
#if BUILDFLAG(ARKWEB_PDF)
  // Clear selection when PDF lose focus.
  if (!has_focus) {
   ClearTextSelection();
  } 
#endif  // BUILDFLAG(ARKWEB_PDF)
  if (caret_) {
    caret_->SetVisible(has_focus && !IsSelecting());
  }
}

AccessibilityFocusInfo PDFiumEngine::GetFocusInfo() {
  AccessibilityFocusInfo focus_info = {FocusObjectType::kNone, 0, 0};

  switch (focus_element_type_) {
    case FocusElementType::kNone: {
      break;
    }
    case FocusElementType::kPage: {
      int page_index = -1;
      FPDF_ANNOTATION focused_annot = nullptr;
      FPDF_BOOL ret = FORM_GetFocusedAnnot(form(), &page_index, &focused_annot);
      DCHECK(ret);

      if (PageIndexInBounds(page_index) && focused_annot) {
        FocusObjectType type =
            GetAnnotationFocusType(FPDFAnnot_GetSubtype(focused_annot));
        int annot_index = FPDFPage_GetAnnotIndex(pages_[page_index]->GetPage(),
                                                 focused_annot);
        if (type != FocusObjectType::kNone && annot_index >= 0) {
          focus_info.focused_object_type = type;
          focus_info.focused_object_page_index = page_index;
          focus_info.focused_annotation_index_in_page = annot_index;
        }
      }
      FPDFPage_CloseAnnot(focused_annot);
      break;
    }
    case FocusElementType::kDocument: {
      focus_info.focused_object_type = FocusObjectType::kDocument;
      break;
    }
  }
  return focus_info;
}

bool PDFiumEngine::IsPDFDocTagged() const {
  return FPDFCatalog_IsTagged(doc());
}

std::unique_ptr<AccessibilityStructureElement> PDFiumEngine::GetStructureTree()
    const {
  auto structure_tree_root = std::make_unique<AccessibilityStructureElement>();
  structure_tree_root->type = PdfTagType::kDocument;
  structure_tree_root->children.reserve(pages_.size());
  // TODO(crbug.com/40707542): Get the /Lang string from
  // AccessibilityStructureElement.
  for (const std::unique_ptr<PDFiumPage>& page : pages_) {
    auto page_structure = page->GetStructureTree();
    if (page_structure) {
      page_structure->parent = structure_tree_root.get();
    }
    structure_tree_root->children.push_back(std::move(page_structure));
  }
  return structure_tree_root;
}

uint32_t PDFiumEngine::GetLoadedByteSize() {
  return doc_loader_->GetDocumentSize();
}

bool PDFiumEngine::ReadLoadedBytes(uint32_t offset,
                                   base::span<uint8_t> buffer) {
  return doc_loader_->GetBlock(offset, buffer);
}

void PDFiumEngine::SetFormSelectedText(FPDF_FORMHANDLE form_handle,
                                       FPDF_PAGE page) {
  std::u16string selected_form_text16 = CallPDFiumWideStringBufferApi(
      base::BindRepeating(&FORM_GetSelectedText, form_handle, page),
      /*check_expected_size=*/false);

  // If form selected text is empty and there was no previous form text
  // selection, exit early because nothing has changed.
  if (selected_form_text16.empty() && selected_form_text_.empty()) {
    return;
  }

  // Update previous and current selections, then compare them to check if
  // selection has changed. If so, set plugin text selection.
  std::string selected_form_text = selected_form_text_;
  selected_form_text_ = base::UTF16ToUTF8(selected_form_text16);
  if (selected_form_text != selected_form_text_) {
    DCHECK_EQ(focus_field_type_, FocusFieldType::kText);
    client_->SetSelectedText(selected_form_text_);
  }
}

void PDFiumEngine::PrintEnd() {
  FORM_DoDocumentAAction(form(), FPDFDOC_AACTION_DP);
}

PDFiumEngine::PointData PDFiumEngine::GetPointData(const gfx::PointF& point) {
  PointData point_data;
  std::optional<uint32_t> page;
  const gfx::Point screen_point = DeviceToScreen(point);
  for (uint32_t visible_page : visible_pages_) {
    if (pages_[visible_page]->rect().Contains(screen_point)) {
      page = visible_page;
      break;
    }
  }
  if (!page.has_value()) {
    return point_data;
  }

  // If the page hasn't finished rendering, calling into the page sometimes
  // leads to hangs.
  for (const auto& paint : progressive_paints_) {
    if (paint.page_index() == page.value()) {
      return point_data;
    }
  }

  point_data.page_index = page.value();
  point_data.pdf_point = DeviceToPdf(page.value(), point);
  PDFiumPage::Area result = pages_[page.value()]->GetCharInfo(
      point_data.pdf_point, &point_data.char_index, &point_data.char_bounds,
      &point_data.form_type, &point_data.target);
  point_data.area =
      (client_->IsPrintPreview() && result == PDFiumPage::WEBLINK_AREA)
          ? PDFiumPage::NONSELECTABLE_AREA
          : result;
  return point_data;
}

// TODO(crbug.com/443275584): Handle vertical text.
int PDFiumEngine::GetCharIndexBasedOnPointData(const PointData& point_data) {
  CHECK(PageIndexInBounds(point_data.page_index));

  bool point_is_left_of_char =
      point_data.pdf_point.x() <
      point_data.char_bounds.AsGfxRectF().CenterPoint().x();
  PDFiumRange current_char(pages_[point_data.page_index].get(),
                           point_data.char_index,
                           /*char_count=*/1);
  // Treat unknown direction as LTR.
  if (base::i18n::GetStringDirection(current_char.GetText()) ==
      base::i18n::RIGHT_TO_LEFT) {
    point_is_left_of_char = !point_is_left_of_char;
  }

  if (point_is_left_of_char) {
    return point_data.char_index;
  }
  return point_data.char_index + 1;
}

bool PDFiumEngine::OnMouseDown(const blink::WebMouseEvent& event) {
  blink::WebMouseEvent normalized_event = NormalizeMouseEvent(event);
  switch (normalized_event.button) {
    case blink::WebPointerProperties::Button::kLeft:
      return OnLeftMouseDown(normalized_event);
    case blink::WebPointerProperties::Button::kMiddle:
      return OnMiddleMouseDown(normalized_event);
    case blink::WebPointerProperties::Button::kRight:
      return OnRightMouseDown(normalized_event);
    default:
      return false;
  }
}

void PDFiumEngine::OnSingleClick(int page_index, int char_index) {
  selection_.push_back(PDFiumRange(pages_[page_index].get(), char_index, 0));
}

void PDFiumEngine::OnMultipleClick(int click_count,
                                   int page_index,
                                   int char_index) {
  CHECK_GE(click_count, 2);
  const bool is_double_click = click_count == 2;

  const int char_count = pages_[page_index]->GetCharCount();
  CHECK_GT(char_count, 0);

  // It would be more efficient if the SDK could support finding a space, but
  // now it doesn't.
  int start_index = char_index;
  do {
    uint32_t cur = pages_[page_index]->GetCharUnicode(start_index);
    if (FindMultipleClickBoundary(is_double_click, cur)) {
      break;
    }
  } while (--start_index >= 0);
  if (start_index && start_index < char_count - 1) {
    start_index++;
  }

  int end_index = char_index;
  for (; end_index < char_count; ++end_index) {
    uint32_t cur = pages_[page_index]->GetCharUnicode(end_index);
    if (FindMultipleClickBoundary(is_double_click, cur)) {
      break;
    }
  }

  selection_.push_back(PDFiumRange(pages_[page_index].get(), start_index,
                                   end_index - start_index));

  if (handling_long_press_) {
    client_->NotifyTouchSelectionOccurred();
  }
}

void PDFiumEngine::OnTextOrLinkAreaClickInternal(const PointData& point_data,
                                                 int click_count) {
  CHECK(IsSelectableArea(point_data.area));
  if (!PageIndexInBounds(point_data.page_index) || point_data.char_index < 0) {
    return;
  }

  if (click_count == 1) {
    int char_index = GetCharIndexBasedOnPointData(point_data);
    OnSingleClick(point_data.page_index, char_index);

    if (caret_) {
      caret_->SetCharAndDraw(
          PageCharacterIndex(point_data.page_index, char_index));
    }
  } else if (click_count >= 2) {
    OnMultipleClick(click_count, point_data.page_index, point_data.char_index);
  }

  if (caret_) {
    caret_->SetVisible(click_count == 1);
  }
}

bool PDFiumEngine::OnLeftMouseDown(const blink::WebMouseEvent& event) {
  DCHECK_EQ(blink::WebPointerProperties::Button::kLeft, event.button);

  SetMouseLeftButtonDown(true);

  auto selection_invalidator =
      std::make_unique<SelectionChangeInvalidator>(this);
  selection_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  const gfx::PointF& point = event.PositionInWidget();
  auto point_data = GetPointData(point);
  DCHECK_GE(point_data.form_type, FPDF_FORMFIELD_UNKNOWN);
  mouse_down_state_.Set(point_data.area, point_data.target);

  // Decide whether to open link or not based on user action in mouse up and
  // mouse move events.
  if (IsLinkArea(point_data.area)) {
    return true;
  }

  int click_count = event.ClickCount();
  if (point_data.page_index != -1) {
    UpdateFocusElementType(FocusElementType::kPage);
    last_focused_page_ = point_data.page_index;

    if (point_data.form_type != FPDF_FORMFIELD_UNKNOWN) {
      // FORM_OnLButton*() will trigger a callback to
      // OnFocusedAnnotationUpdated(), which will call SetFieldFocus().
      // Destroy SelectionChangeInvalidator object before SetFieldFocus()
      // changes plugin's focus to be `FocusFieldType::kText`. This way, regular
      // text selection can be cleared when a user clicks into a form text area
      // because the pp::PDF::SetSelectedText() call in
      // ~SelectionChangeInvalidator() still goes to the Mimehandler
      // (not the Renderer).
      selection_invalidator.reset();
    }

    FPDF_PAGE page = pages_[point_data.page_index]->GetPage();

    if (click_count == 1) {
      FORM_OnLButtonDown(form(), page, event.GetModifiers(),
                         point_data.pdf_point.x(), point_data.pdf_point.y());
    } else if (click_count == 2) {
      FORM_OnLButtonDoubleClick(form(), page, event.GetModifiers(),
                                point_data.pdf_point.x(),
                                point_data.pdf_point.y());
    }
    if (point_data.form_type != FPDF_FORMFIELD_UNKNOWN) {
      return true;  // Return now before we get into the selection code.
    }
  }
  SetFieldFocus(FocusFieldType::kNoFocus);

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
  client_->MaybeShowSearchifyInProgress();
#endif

  if (point_data.area != PDFiumPage::TEXT_AREA) {
    return true;  // Return true so WebKit doesn't do its own highlighting.
  }

  if (click_count == 1) {
    SetSelecting(true);
  }

  OnTextOrLinkAreaClickInternal(point_data, click_count);
  return true;
}

bool PDFiumEngine::OnMiddleMouseDown(const blink::WebMouseEvent& event) {
  DCHECK_EQ(blink::WebPointerProperties::Button::kMiddle, event.button);

  SetMouseLeftButtonDown(false);
  mouse_middle_button_last_position_ = event.PositionInWidget();

  ClearTextSelection();

  auto point_data = GetPointData(mouse_middle_button_last_position_.value());
  mouse_down_state_.Set(point_data.area, point_data.target);

  // Decide whether to open link or not based on user action in mouse up and
  // mouse move events.
  if (IsLinkArea(point_data.area)) {
    return true;
  }

  if (kViewerImplementedPanning) {
    // Switch to hand cursor when panning.
    client_->UpdateCursor(ui::mojom::CursorType::kHand);
  }

  // Prevent middle mouse button from selecting texts.
  return false;
}

bool PDFiumEngine::OnRightMouseDown(const blink::WebMouseEvent& event) {
  DCHECK_EQ(blink::WebPointerProperties::Button::kRight, event.button);

  const gfx::PointF& point = event.PositionInWidget();
  auto point_data = GetPointData(point);
  DCHECK_GE(point_data.form_type, FPDF_FORMFIELD_UNKNOWN);

  bool is_form_text_area =
      IsFormTextArea(point_data.area, point_data.form_type);

  FPDF_PAGE page = nullptr;
  if (is_form_text_area) {
    DCHECK_NE(point_data.page_index, -1);

    page = pages_[point_data.page_index]->GetPage();
  }

  // Handle the case when focus starts inside a form text area.
  if (focus_field_type_ == FocusFieldType::kText) {
    if (is_form_text_area) {
      FORM_OnFocus(form(), page, 0, point_data.pdf_point.x(),
                   point_data.pdf_point.y());
    } else {
      // Transition out of a form text area.
      KillFormFocus();
    }
    return true;
  }

  // Handle the case when focus starts outside a form text area and transitions
  // into a form text area.
  if (is_form_text_area) {
    FORM_OnFocus(form(), page, 0, point_data.pdf_point.x(),
                 point_data.pdf_point.y());
    return true;
  }

  // Before examining the selection, first refresh the link. Due to keyboard
  // events and possibly other events, the saved link info may be stale.
  UpdateLinkUnderCursor(GetLinkAtPosition(point));

  // Handle the case when focus starts outside a form text area and stays
  // outside.
  if (selection_.empty()) {
    return false;
  }

  std::vector<gfx::Rect> selection_rect_vector =
      GetAllScreenRectsUnion(selection_, GetVisibleRect().origin());
  const gfx::Point rounded_point = gfx::ToRoundedPoint(point);
  for (const auto& rect : selection_rect_vector) {
    if (rect.Contains(rounded_point)) {
      return false;
    }
  }

  ClearTextSelection();
  return true;
}

bool PDFiumEngine::NavigateToLinkDestination(
    PDFiumPage::Area area,
    const PDFiumPage::LinkTarget& target,
    WindowOpenDisposition disposition) {
  if (area == PDFiumPage::WEBLINK_AREA) {
    client_->NavigateTo(target.url, disposition);
    SetFieldFocus(FocusFieldType::kNoFocus);
    return true;
  }
  if (area == PDFiumPage::DOCLINK_AREA) {
    if (!PageIndexInBounds(target.page)) {
      return true;
    }

    if (disposition == WindowOpenDisposition::CURRENT_TAB) {
      client_->NavigateToDestination(target.page,
                                     base::OptionalToPtr(target.x_in_pixels),
                                     base::OptionalToPtr(target.y_in_pixels),
                                     base::OptionalToPtr(target.zoom));
    } else {
      std::string parameters = base::StringPrintf("#page=%d", target.page + 1);
      parameters += base::StringPrintf(
          "&zoom=%d,%d,%d", static_cast<int>(target.zoom.value_or(1.0) * 100),
          static_cast<int>(target.x_in_pixels.value_or(0)),
          static_cast<int>(target.y_in_pixels.value_or(0)));

      client_->NavigateTo(parameters, disposition);
    }
    SetFieldFocus(FocusFieldType::kNoFocus);
    return true;
  }
  return false;
}

bool PDFiumEngine::OnMouseUp(const blink::WebMouseEvent& event) {
  if (event.button != blink::WebPointerProperties::Button::kLeft &&
      event.button != blink::WebPointerProperties::Button::kMiddle) {
    return false;
  }

  if (event.button == blink::WebPointerProperties::Button::kLeft) {
    SetMouseLeftButtonDown(false);
  } else if (event.button == blink::WebPointerProperties::Button::kMiddle) {
    mouse_middle_button_last_position_.reset();
  }

  const gfx::PointF& point = event.PositionInWidget();
  auto point_data = GetPointData(point);

  // Open link on mouse up for same link for which mouse down happened earlier.
  if (mouse_down_state_.Matches(point_data.area, point_data.target)) {
    int modifiers = event.GetModifiers();
    bool middle_button =
        !!(modifiers & blink::WebInputEvent::Modifiers::kMiddleButtonDown);
    bool alt_key = !!(modifiers & blink::WebInputEvent::Modifiers::kAltKey);
    bool ctrl_key =
        !!(modifiers & blink::WebInputEvent::Modifiers::kControlKey);
    bool meta_key = !!(modifiers & blink::WebInputEvent::Modifiers::kMetaKey);
    bool shift_key = !!(modifiers & blink::WebInputEvent::Modifiers::kShiftKey);

    WindowOpenDisposition disposition = ui::DispositionFromClick(
        middle_button, alt_key, ctrl_key, meta_key, shift_key);

    if (NavigateToLinkDestination(point_data.area, point_data.target,
                                  disposition)) {
      return true;
    }
  }

  if (event.button == blink::WebPointerProperties::Button::kMiddle) {
    if (kViewerImplementedPanning) {
      // Update the cursor when panning stops.
      client_->UpdateCursor(
          DetermineCursorType(point_data.area, point_data.form_type));
    }

    // Prevent middle mouse button from selecting texts.
    return false;
  }

  if (point_data.page_index != -1) {
    FORM_OnLButtonUp(form(), pages_[point_data.page_index]->GetPage(),
                     event.GetModifiers(), point_data.pdf_point.x(),
                     point_data.pdf_point.y());
  }

  if (!selecting_) {
    return false;
  }

  SetSelecting(false);
  return true;
}

bool PDFiumEngine::OnMouseMove(const blink::WebMouseEvent& event) {
  const gfx::PointF& point = event.PositionInWidget();
  auto point_data = GetPointData(point);

  // Clear `mouse_down_state_` if mouse moves away from where the mouse down
  // happened.
  if (!mouse_down_state_.Matches(point_data.area, point_data.target)) {
    mouse_down_state_.Reset();
  }

  if (!selecting_) {
    client_->UpdateCursor(
        DetermineCursorType(point_data.area, point_data.form_type));

    if (point_data.page_index != -1) {
      FORM_OnMouseMove(form(), pages_[point_data.page_index]->GetPage(), 0,
                       point_data.pdf_point.x(), point_data.pdf_point.y());
    }

    UpdateLinkUnderCursor(GetLinkAtPosition(point));

    // If in form text area while left mouse button is held down, check if form
    // text selection needs to be updated.
    if (mouse_left_button_down_ &&
        point_data.area == PDFiumPage::FORM_TEXT_AREA &&
        PageIndexInBounds(last_focused_page_)) {
      SetFormSelectedText(form(), pages_[last_focused_page_]->GetPage());
    }

    if (kViewerImplementedPanning &&
        mouse_middle_button_last_position_.has_value()) {
      // Subtract (origin - destination) so delta is already the delta for
      // moving the page, rather than the delta the mouse moved.
      // `event.movement_x` and `event.movement_y` do not work here, as small
      // mouse movements are considered zero.
      gfx::Vector2d page_position_delta = gfx::ToRoundedVector2d(
          mouse_middle_button_last_position_.value() - point);
      if (page_position_delta.x() != 0 || page_position_delta.y() != 0) {
        client_->ScrollBy(page_position_delta);
        mouse_middle_button_last_position_ = point;
      }
    }

    // No need to swallow the event, since this might interfere with the
    // scrollbars if the user is dragging them.
    return false;
  }

  // We're selecting but right now we're not over text, so don't change the
  // current selection.
  if (!PageIndexInBounds(point_data.page_index) || point_data.char_index < 0) {
    return false;
  }

  // Similarly, do not select if `area` is not a selectable type. This can occur
  // even if there is text in the area. e.g. When print previewing.
  if (!IsSelectableArea(point_data.area)) {
    return false;
  }

  SelectionChangeInvalidator selection_invalidator(this);
  return ExtendSelection(point_data);
}

ui::mojom::CursorType PDFiumEngine::DetermineCursorType(PDFiumPage::Area area,
                                                        int form_type) const {
  if (kViewerImplementedPanning &&
      mouse_middle_button_last_position_.has_value()) {
    return ui::mojom::CursorType::kHand;
  }

  switch (area) {
    case PDFiumPage::TEXT_AREA:
      return ui::mojom::CursorType::kIBeam;
    case PDFiumPage::WEBLINK_AREA:
    case PDFiumPage::DOCLINK_AREA:
      return ui::mojom::CursorType::kHand;
    case PDFiumPage::NONSELECTABLE_AREA:
    case PDFiumPage::FORM_TEXT_AREA:
    default:
      switch (form_type) {
        case FPDF_FORMFIELD_PUSHBUTTON:
        case FPDF_FORMFIELD_CHECKBOX:
        case FPDF_FORMFIELD_RADIOBUTTON:
        case FPDF_FORMFIELD_COMBOBOX:
        case FPDF_FORMFIELD_LISTBOX:
          return ui::mojom::CursorType::kHand;
        case FPDF_FORMFIELD_TEXTFIELD:
          return ui::mojom::CursorType::kIBeam;
#if defined(PDF_ENABLE_XFA)
        case FPDF_FORMFIELD_XFA_CHECKBOX:
        case FPDF_FORMFIELD_XFA_COMBOBOX:
        case FPDF_FORMFIELD_XFA_IMAGEFIELD:
        case FPDF_FORMFIELD_XFA_LISTBOX:
        case FPDF_FORMFIELD_XFA_PUSHBUTTON:
        case FPDF_FORMFIELD_XFA_SIGNATURE:
          return ui::mojom::CursorType::kHand;
        case FPDF_FORMFIELD_XFA_TEXTFIELD:
          return ui::mojom::CursorType::kIBeam;
#endif
        default:
          return ui::mojom::CursorType::kPointer;
      }
  }
}

void PDFiumEngine::OnMouseEnter(const blink::WebMouseEvent& event) {
  if (event.GetModifiers() &
      blink::WebInputEvent::Modifiers::kMiddleButtonDown) {
    if (!mouse_middle_button_last_position_.has_value()) {
      mouse_middle_button_last_position_ = event.PositionInWidget();
    }
  } else {
    mouse_middle_button_last_position_.reset();
  }
}

bool PDFiumEngine::ExtendSelection(const PointData& point_data) {
  CHECK(PageIndexInBounds(point_data.page_index));
  CHECK_GE(point_data.char_index, 0);

  const uint32_t char_index = GetCharIndexBasedOnPointData(point_data);
  PageCharacterIndex index{static_cast<uint32_t>(point_data.page_index),
                           char_index};
  const bool extended = ExtendSelectionByChar(index);
  if (caret_) {
    caret_->SetChar(index);
    caret_->SetVisible(!IsSelecting());
  }
  return extended;
}

bool PDFiumEngine::ExtendSelectionByChar(const PageCharacterIndex& index) {
  // Check if the user has decreased their selection area and we need to remove
  // pages from `selection_`.
  for (size_t i = 0; i < selection_.size(); ++i) {
    if (selection_[i].page_index() == index.page_index) {
      // There should be no other pages after this.
      selection_.erase(selection_.begin() + i + 1, selection_.end());
      break;
    }
  }
  if (selection_.empty()) {
    return false;
  }

  const uint32_t last_page_index = selection_.back().page_index();
  const int last_char_index = selection_.back().char_index();
  if (last_page_index == index.page_index) {
    // Selecting within a page.
    int count = index.char_index - last_char_index;
    if (count >= 0) {
      // Selecting forward.
      selection_.back().SetCharCount(count);
    } else {
      // CreateBackwards() expects a positive count, so flip the negative value.
      count = -count;
      selection_.back() = PDFiumRange::CreateBackwards(
          pages_[index.page_index].get(), index.char_index, count);
    }
  } else if (last_page_index < index.page_index) {
    // Selecting into the next page.

    // Save the current last selection for use below.
    // Warning: Do not use references / pointers into `selection_`, as the code
    // below can modify `selection_` and invalidate those references / pointers.
    const size_t last_selection_index = selection_.size() - 1;

    // First make sure that there are no gaps in selection, i.e. if mousedown on
    // page one but we only get mousemove over page three, we want page two.
    for (uint32_t i = last_page_index + 1; i < index.page_index; ++i) {
      if (pages_[i]->GetCharCount()) {
        selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
      }
    }

    int count = pages_[last_page_index]->GetCharCount();
    selection_[last_selection_index].SetCharCount(count - last_char_index);
    selection_.push_back(PDFiumRange(pages_[index.page_index].get(),
                                     /*char_index=*/0,
                                     /*char_count=*/index.char_index));
  } else {
    // Selecting into the previous page.
    // `last_page_index` has already been adjusted previously to either include
    // the current character or not, so use it as-is.
    // This selection needs to be backwards.
    selection_.back() = PDFiumRange::CreateBackwards(
        pages_[last_page_index].get(), /*char_index=*/0,
        /*char_count=*/last_char_index);

    // First make sure that there are no gaps in selection, i.e. if mousedown on
    // page three but we only get mousemove over page one, we want page two.
    for (uint32_t i = last_page_index - 1; i > index.page_index; --i) {
      if (pages_[i]->GetCharCount()) {
        selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
      }
    }

    int char_count =
        pages_[index.page_index]->GetCharCount() - index.char_index;
    selection_.push_back(PDFiumRange::CreateBackwards(
        pages_[index.page_index].get(), index.char_index, char_count));
  }

  return true;
}

bool PDFiumEngine::OnKeyDown(const blink::WebKeyboardEvent& event) {
  // Handle tab events first as we might need to transition focus to an
  // annotation in PDF.
  if (event.windows_key_code == FWL_VKEY_Tab) {
    return HandleTabEvent(event.GetModifiers());
  }
  if (focus_field_type_ == FocusFieldType::kNoFocus && caret_ &&
      caret_->OnKeyDown(event)) {
    return true;
  }

  if (!PageIndexInBounds(last_focused_page_)) {
    return false;
  }

  bool rv = !!FORM_OnKeyDown(form(), pages_[last_focused_page_]->GetPage(),
                             event.windows_key_code, event.GetModifiers());

  if (!event.IsCharacterKey()) {
    // Blink does not send char events for backspace or escape keys, see
    // `blink::WebKeyboardEvent::IsCharacterKey()` and b/961192 for more
    // information. So just fake one since PDFium uses it.
    blink::WebKeyboardEvent synthesized(blink::WebInputEvent::Type::kChar,
                                        event.GetModifiers(),
                                        event.TimeStamp());
    synthesized.windows_key_code = event.windows_key_code;
    synthesized.text[0] = synthesized.windows_key_code;
    synthesized.text[1] = L'\0';
    OnChar(synthesized);
  }

#if !BUILDFLAG(IS_MAC)
  // macOS doesn't have keyboard-triggered context menus.
  // Scroll focused annotation into view when context menu is invoked through
  // keyboard <Shift-F10>.
  if (event.windows_key_code == FWL_VKEY_F10 &&
      (event.GetModifiers() & blink::WebInputEvent::Modifiers::kShiftKey)) {
    DCHECK(!rv);
    ScrollFocusedAnnotationIntoView();
  }
#endif

  return rv;
}

bool PDFiumEngine::OnKeyUp(const blink::WebKeyboardEvent& event) {
  if (!PageIndexInBounds(last_focused_page_)) {
    return false;
  }

  // Check if form text selection needs to be updated.
  FPDF_PAGE page = pages_[last_focused_page_]->GetPage();
  if (focus_field_type_ == FocusFieldType::kText) {
    SetFormSelectedText(form(), page);
  }

  return !!FORM_OnKeyUp(form(), page, event.windows_key_code,
                        event.GetModifiers());
}

bool PDFiumEngine::OnChar(const blink::WebKeyboardEvent& event) {
  if (!PageIndexInBounds(last_focused_page_)) {
    return false;
  }

  bool rv = !!FORM_OnChar(form(), pages_[last_focused_page_]->GetPage(),
                          event.text[0], event.GetModifiers());

  // Scroll editable form text into view on char events. We should not scroll
  // focused annotation on escape char event since escape char is used to
  // dismiss focus from form controls.
  if (rv && editable_form_text_area_ &&
      event.windows_key_code != ui::VKEY_ESCAPE) {
    ScrollFocusedAnnotationIntoView();
  }

  return rv;
}

void PDFiumEngine::StartFind(const std::u16string& text, bool case_sensitive) {
  // If the caller asks StartFind() to search for no text, then this is an
  // error on the part of the caller. The `blink::FindInPage` code guarantees it
  // is not empty, so this should never happen.
  DCHECK(!text.empty());

  // If StartFind() gets called before we have any page information (i.e.
  // before the first call to LoadDocument has happened). Handle this case.
  if (pages_.empty()) {
    client_->NotifyNumberOfFindResultsChanged(0, true);
    return;
  }

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
  client_->MaybeShowSearchifyInProgress();
#endif

  bool first_search = (current_find_text_ != text);
  int character_to_start_searching_from = 0;
  if (first_search) {
    // Do not move `selection_` here, as StopFind() expects to start with the
    // existing selection.
    std::vector<PDFiumRange> old_selection = selection_;
    StopFind();
    current_find_text_ = text;

    if (old_selection.empty()) {
      // Start searching from the beginning of the document.
      next_page_to_search_ = 0;
      last_page_to_search_ = pages_.size() - 1;
      last_character_index_to_search_ = -1;
    } else {
      // There's a current selection, so start from it.
      next_page_to_search_ = old_selection[0].page_index();
      last_character_index_to_search_ = old_selection[0].char_index();
      character_to_start_searching_from = old_selection[0].char_index();
      last_page_to_search_ = next_page_to_search_;
    }
    search_in_progress_ = true;
  }

  int current_page = next_page_to_search_;

  if (pages_[current_page]->available()) {
    SearchUsingICU(
        text, case_sensitive, first_search, character_to_start_searching_from,
        last_character_index_to_search_, current_page, last_page_to_search_,
        base::BindRepeating(&PDFiumEngine::AddFindResult,
                            weak_factory_.GetWeakPtr()));

    if (!IsPageVisible(current_page)) {
      pages_[current_page]->Unload();
    }
  }

  if (next_page_to_search_ != last_page_to_search_ ||
      (first_search && last_character_index_to_search_ != -1)) {
    ++next_page_to_search_;
  }

  if (next_page_to_search_ == static_cast<int>(pages_.size())) {
    next_page_to_search_ = 0;
  }
  // If there's only one page in the document and we start searching midway,
  // then we'll want to search the page one more time.
  bool end_of_search =
      next_page_to_search_ == last_page_to_search_ &&
      // Only one page but didn't start midway.
      ((pages_.size() == 1 && last_character_index_to_search_ == -1) ||
       // Started midway, but only 1 page and we already looped around.
       (pages_.size() == 1 && !first_search) ||
       // Started midway, and we've just looped around.
       (pages_.size() > 1 && current_page == next_page_to_search_));

  if (end_of_search) {
    search_in_progress_ = false;

    // Send the final notification.
    client_->NotifyNumberOfFindResultsChanged(find_results_.size(), true);
    return;
  }

  // In unit tests, just call ContinueFind() directly for simplicity and reduce
  // the need to use RunLoops.
  if (doc_loader_set_for_testing_) {
    ContinueFind(case_sensitive);
  } else {
    base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
        FROM_HERE,
        base::BindOnce(&PDFiumEngine::ContinueFind,
                       find_weak_factory_.GetWeakPtr(), case_sensitive));
  }
}

void PDFiumEngine::SearchUsingICU(const std::u16string& term,
                                  bool case_sensitive,
                                  bool first_search,
                                  int character_to_start_searching_from,
                                  int last_character_index_to_search,
                                  int current_page,
                                  int last_page_to_search,
                                  AddSearchResultCallback add_result_callback) {
  DCHECK(!term.empty());

  // Various types of quotions marks need to be converted to the simple ASCII
  // version for searching to get better matching.
  std::u16string adjusted_term = term;
  for (char16_t& c : adjusted_term) {
    c = SimplifyForSearch(c);
  }

  const int original_text_length = pages_[current_page]->GetCharCount();
  int text_length = original_text_length;
  if (character_to_start_searching_from) {
    text_length -= character_to_start_searching_from;
  } else if (!first_search && last_character_index_to_search != -1 &&
             current_page == last_page_to_search) {
    text_length = last_character_index_to_search;
  }
  if (text_length <= 0) {
    return;
  }

  std::u16string page_text;
  PDFiumAPIStringBufferAdapter<std::u16string> api_string_adapter(
      &page_text, text_length, false);
  unsigned short* data =
      reinterpret_cast<unsigned short*>(api_string_adapter.GetData());
  int written =
      FPDFText_GetText(pages_[current_page]->GetTextPage(),
                       character_to_start_searching_from, text_length, data);
  api_string_adapter.Close(written);

  const gfx::RectF page_bounds = pages_[current_page]->GetCroppedRect();
  std::u16string adjusted_page_text;
  adjusted_page_text.reserve(page_text.size());
  // Values in `removed_indices` are in the adjusted text index space and
  // indicate a character was removed from the page text before the given
  // index. If multiple characters are removed in a row then there will be
  // multiple entries with the same value.
  std::vector<size_t> removed_indices;
  // When walking through the page text collapse any whitespace regions,
  // including \r and \n, down to a single ' ' character. This code does
  // not use base::CollapseWhitespace(), because that function does not
  // return where the collapsing occurs, but uses the same underlying list of
  // whitespace characters. Calculating where the collapsed regions are after
  // the fact is as complex as collapsing them manually.
  for (size_t i = 0; i < page_text.size(); i++) {
    // Filter out characters outside the page bounds, which are semantically not
    // part of the page.
    if (!pages_[current_page]->IsCharInPageBounds(
            character_to_start_searching_from + i, page_bounds)) {
      removed_indices.push_back(adjusted_page_text.size());
      continue;
    }

    char16_t c = page_text[i];
    // Collapse whitespace regions by inserting a ' ' into the
    // adjusted text and recording any removed whitespace indices as preceding
    // it.
    if (base::IsUnicodeWhitespace(c)) {
      size_t whitespace_region_begin = i;
      while (i < page_text.size() && base::IsUnicodeWhitespace(page_text[i])) {
        ++i;
      }

      size_t count = i - whitespace_region_begin - 1;
      removed_indices.insert(removed_indices.end(), count,
                             adjusted_page_text.size());
      adjusted_page_text.push_back(' ');
      if (i >= page_text.size()) {
        break;
      }
      c = page_text[i];
    }

    if (IsIgnorableCharacter(c)) {
      removed_indices.push_back(adjusted_page_text.size());
    } else {
      adjusted_page_text.push_back(SimplifyForSearch(c));
    }
  }

  if (adjusted_page_text.empty()) {
    return;
  }

  std::vector<PDFiumEngineClient::SearchStringResult> results =
      client_->SearchString(adjusted_term, adjusted_page_text, case_sensitive);
  for (const auto& result : results) {
    // Need to convert from adjusted page text start to page text start, by
    // incrementing for all the characters adjusted before it in the string.
    auto removed_indices_begin = std::upper_bound(
        removed_indices.begin(), removed_indices.end(), result.start_index);
    size_t page_text_result_start_index =
        result.start_index +
        std::distance(removed_indices.begin(), removed_indices_begin);

    // Need to convert the adjusted page length into a page text length, since
    // the matching range may have adjusted characters within it. This
    // conversion only cares about skipped characters in the result interval.
    auto removed_indices_end =
        std::upper_bound(removed_indices_begin, removed_indices.end(),
                         result.start_index + result.length);
    int term_removed_count =
        std::distance(removed_indices_begin, removed_indices_end);
    int page_text_result_length = result.length + term_removed_count;

    // Need to map the indexes from the page text, which may have generated
    // characters like space etc, to character indices from the page.
    int text_to_start_searching_from = FPDFText_GetTextIndexFromCharIndex(
        pages_[current_page]->GetTextPage(), character_to_start_searching_from);
    int temp_start =
        page_text_result_start_index + text_to_start_searching_from;
    int start = FPDFText_GetCharIndexFromTextIndex(
        pages_[current_page]->GetTextPage(), temp_start);
    int end = FPDFText_GetCharIndexFromTextIndex(
        pages_[current_page]->GetTextPage(),
        temp_start + page_text_result_length);

    // If `term` occurs at the end of a page, then `end` will be -1 due to the
    // index being out of bounds. Compensate for this case so the range
    // character count calculation below works out.
    if (temp_start + page_text_result_length == original_text_length) {
      DCHECK_EQ(-1, end);
      end = original_text_length;
    }
    DCHECK_LT(start, end);
    DCHECK_EQ(term.size() + term_removed_count,
              static_cast<size_t>(end - start));
    add_result_callback.Run(
        PDFiumRange(pages_[current_page].get(), start, end - start));
  }
}

void PDFiumEngine::AddFindResult(PDFiumRange result) {
  // Figure out where to insert the new location, since we could have
  // started searching midway and now we wrapped.
  size_t result_index;
  uint32_t page_index = result.page_index();
  int char_index = result.char_index();
  for (result_index = 0; result_index < find_results_.size(); ++result_index) {
    if (find_results_[result_index].page_index() > page_index ||
        (find_results_[result_index].page_index() == page_index &&
         find_results_[result_index].char_index() > char_index)) {
      break;
    }
  }
  find_results_.insert(find_results_.begin() + result_index, std::move(result));
  UpdateTickMarks();
  client_->NotifyNumberOfFindResultsChanged(find_results_.size(), false);
}

const PDFiumRange* PDFiumEngine::GetFindSelection() const {
  if (!current_find_index_.has_value()) {
    return nullptr;
  }
  return &find_results_[current_find_index_.value()];
}

bool PDFiumEngine::SelectFindResult(bool forward) {
  if (find_results_.empty()) {
    return false;
  }

  // Invalidate the previous find selection.
  FindResultChangeInvalidator find_change_invalidator(this);

#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = true;
#endif  // BUILDFLAG(ARKWEB_PDF)

  // Move back/forward through the search locations we previously found.
  size_t new_index;
  const size_t last_index = find_results_.size() - 1;

  if (resume_find_index_) {
    new_index = resume_find_index_.value();
    resume_find_index_.reset();
  } else if (current_find_index_) {
    size_t current_index = current_find_index_.value();
    if ((forward && current_index >= last_index) ||
        (!forward && current_index == 0)) {
      current_find_index_.reset();
      client_->NotifySelectedFindResultChanged(-1, /*final_result=*/false);
      client_->NotifyNumberOfFindResultsChanged(find_results_.size(),
                                                /*final_result=*/true);
      return true;
    }
    int increment = forward ? 1 : -1;
    new_index = current_index + increment;
  } else {
    new_index = forward ? 0 : last_index;
  }
  current_find_index_ = new_index;

  // Clear the current text selection.
  SelectionChangeInvalidator selection_invalidator(this);
  selection_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  // If the result is not in view, scroll to it.
  ScrollToBoundingRects(find_results_[current_find_index_.value()],
                        /*force_smooth_scroll=*/false);

  client_->NotifySelectedFindResultChanged(
      current_find_index_.value(), /*final_result=*/!search_in_progress_);
  return true;
}

void PDFiumEngine::StopFind() {
  FindResultChangeInvalidator find_change_invalidator(this);
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  find_results_.clear();
  next_page_to_search_ = -1;
  last_page_to_search_ = -1;
  last_character_index_to_search_ = -1;
  current_find_index_.reset();
  current_find_text_.clear();

  UpdateTickMarks();
  find_weak_factory_.InvalidateWeakPtrs();
}

std::vector<gfx::Rect> PDFiumEngine::GetAllScreenRectsUnion(
    base::span<const PDFiumRange> rect_range,
    const gfx::Point& point) const {
  std::vector<gfx::Rect> rect_vector;
  rect_vector.reserve(rect_range.size());
  for (const auto& range : rect_range) {
    const std::vector<gfx::Rect>& rects =
        range.GetScreenRects(point, current_zoom_, GetCurrentOrientation());
    rect_vector.push_back(gfx::UnionRects(rects));
  }
  return rect_vector;
}

void PDFiumEngine::UpdateTickMarks() {
  std::vector<gfx::Rect> tickmarks =
      GetAllScreenRectsUnion(find_results_, gfx::Point());
  client_->UpdateTickMarks(tickmarks);
}

void PDFiumEngine::ZoomUpdated(double new_zoom_level) {
  CancelPaints();

  current_zoom_ = new_zoom_level;

  CalculateVisiblePages();
  UpdateTickMarks();
}

void PDFiumEngine::RotateClockwise() {
  SaveSelection();
  desired_layout_options_.RotatePagesClockwise();
  ProposeNextDocumentLayout();
}

void PDFiumEngine::RotateCounterclockwise() {
  SaveSelection();
  desired_layout_options_.RotatePagesCounterclockwise();
  ProposeNextDocumentLayout();
}

bool PDFiumEngine::IsReadOnly() const {
  return read_only_;
}

void PDFiumEngine::SetReadOnly(bool read_only) {
  read_only_ = read_only;
  SetFormHighlight(!read_only_);
  ClearTextSelection();
}

void PDFiumEngine::SetDocumentLayout(DocumentLayout::PageSpread page_spread) {
  SaveSelection();
  desired_layout_options_.set_page_spread(page_spread);
  ProposeNextDocumentLayout();
}

void PDFiumEngine::DisplayAnnotations(bool display) {
  if (render_annots_ == display) {
    return;
  }

  render_annots_ = display;
  InvalidateAllPages();
}

std::u16string PDFiumEngine::GetPageText(int page_index) {
  CHECK(PageIndexInBounds(page_index));
  auto range = PDFiumRange::AllTextOnPage(pages_[page_index].get());
  return range.GetText();
}

void PDFiumEngine::InvalidateAllPages() {
  CancelPaints();
  StopFind();
  DCHECK(document_loaded_);
  RefreshCurrentDocumentLayout();
  client_->Invalidate(gfx::Rect(plugin_size()));
}

std::string PDFiumEngine::GetSelectedText() {
  std::u16string result;
  for (size_t i = 0; i < selection_.size(); ++i) {
    std::u16string current_selection_text = selection_[i].GetText();
    if (i != 0) {
      if (selection_[i - 1].page_index() > selection_[i].page_index()) {
        std::swap(current_selection_text, result);
      }
#if BUILDFLAG(IS_WIN)
      result.push_back(L'\r');
#endif
      result.push_back(L'\n');
    }
    result.append(current_selection_text);
  }

  FormatStringWithHyphens(&result);
  FormatStringForOS(&result);
  return base::UTF16ToUTF8(result);
}

bool PDFiumEngine::CanEditText() const {
  return editable_form_text_area_;
}

bool PDFiumEngine::HasEditableText() const {
  DCHECK(CanEditText());
  if (!PageIndexInBounds(last_focused_page_)) {
    return false;
  }

  FPDF_PAGE page = pages_[last_focused_page_]->GetPage();
  // If the return value is 2, that corresponds to "\0\0".
  return FORM_GetFocusedText(form(), page, nullptr, 0) > 2;
}

void PDFiumEngine::ReplaceSelection(const std::string& text) {
  DCHECK(CanEditText());
  if (!PageIndexInBounds(last_focused_page_)) {
    return;
  }

  std::u16string text_wide = base::UTF8ToUTF16(text);
  FORM_ReplaceSelection(form(), pages_[last_focused_page_]->GetPage(),
                        reinterpret_cast<FPDF_WIDESTRING>(text_wide.c_str()));
}

bool PDFiumEngine::CanUndo() const {
  return PageIndexInBounds(last_focused_page_) &&
         FORM_CanUndo(form(), pages_[last_focused_page_]->GetPage());
}

bool PDFiumEngine::CanRedo() const {
  return PageIndexInBounds(last_focused_page_) &&
         FORM_CanRedo(form(), pages_[last_focused_page_]->GetPage());
}

void PDFiumEngine::Undo() {
  if (!PageIndexInBounds(last_focused_page_)) {
    return;
  }

  FORM_Undo(form(), pages_[last_focused_page_]->GetPage());
}

void PDFiumEngine::Redo() {
  if (!PageIndexInBounds(last_focused_page_)) {
    return;
  }

  FORM_Redo(form(), pages_[last_focused_page_]->GetPage());
}

void PDFiumEngine::HandleAccessibilityAction(
    const AccessibilityActionData& action_data) {
  switch (action_data.action) {
    case AccessibilityAction::kScrollToMakeVisible: {
      ScrollBasedOnScrollAlignment(action_data.target_rect,
                                   action_data.horizontal_scroll_alignment,
                                   action_data.vertical_scroll_alignment);
      return;
    }
    case AccessibilityAction::kDoDefaultAction: {
      if (PageIndexInBounds(action_data.page_index)) {
        if (action_data.annotation_type == AccessibilityAnnotationType::kLink) {
          PDFiumPage::LinkTarget target;
          PDFiumPage::Area area =
              pages_[action_data.page_index]->GetLinkTargetAtIndex(
                  action_data.annotation_index, &target);
          NavigateToLinkDestination(area, target,
                                    WindowOpenDisposition::CURRENT_TAB);
        }
      }
      return;
    }
    case AccessibilityAction::kScrollToGlobalPoint: {
      ScrollToGlobalPoint(action_data.target_rect, action_data.target_point);
      return;
    }
    case AccessibilityAction::kSetSelection: {
      if (IsPageCharacterIndexInBounds(action_data.selection_start_index) &&
          IsPageCharacterIndexInBounds(action_data.selection_end_index)) {
        SetSelection(action_data.selection_start_index,
                     action_data.selection_end_index);
        gfx::Rect target_rect = action_data.target_rect;
        if (!GetVisibleRect().Contains(target_rect)) {
          client_->ScrollBy(GetScreenRect(target_rect).OffsetFromOrigin());
        }
      }
      return;
    }
    case AccessibilityAction::kNone:
      NOTREACHED();
  }
  NOTREACHED();
}

std::string PDFiumEngine::GetLinkAtPosition(const gfx::PointF& point) {
  auto point_data = GetPointData(point);
  return point_data.area == PDFiumPage::WEBLINK_AREA ? point_data.target.url
                                                     : std::string();
}

bool PDFiumEngine::HasPermission(DocumentPermission permission) const {
  // No `permissions_` means no restrictions.
  if (!permissions_) {
    return true;
  }
  return permissions_->HasPermission(permission);
}

void PDFiumEngine::SelectAll() {
  if (IsReadOnly()) {
    return;
  }

#if BUILDFLAG(ENABLE_PDF_INK2)
  if (client_->IsInAnnotationMode()) {
    return;
  }
#endif  // BUILDFLAG(ENABLE_PDF_INK2)

  if (focus_field_type_ == FocusFieldType::kText) {
    if (PageIndexInBounds(last_focused_page_)) {
      FPDF_PAGE page = pages_[last_focused_page_]->GetPage();
      FORM_SelectAllText(form(), page);
      SetFormSelectedText(form(), page);
    }
    return;
  }

  SelectionChangeInvalidator selection_invalidator(this);

  selection_.clear();
  for (const auto& page : pages_) {
    if (page->GetCharCount()) {
      selection_.push_back(PDFiumRange::AllTextOnPage(page.get()));
    }
  }
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  if (caret_ && IsSelecting()) {
    caret_->SetVisible(false);
  }
}

const std::vector<DocumentAttachmentInfo>&
PDFiumEngine::GetDocumentAttachmentInfoList() const {
  DCHECK(document_loaded_);
  return doc_attachment_info_list_;
}

std::vector<uint8_t> PDFiumEngine::GetAttachmentData(size_t index) {
  DCHECK_LT(index, doc_attachment_info_list_.size());
  DCHECK(doc_attachment_info_list_[index].is_readable);
  unsigned long length_bytes = doc_attachment_info_list_[index].size_bytes;
  DCHECK_NE(length_bytes, 0u);

  FPDF_ATTACHMENT attachment = FPDFDoc_GetAttachment(doc(), index);
  std::vector<uint8_t> content_buf(length_bytes);
  unsigned long data_size_bytes;
  bool is_attachment_readable = FPDFAttachment_GetFile(
      attachment, content_buf.data(), length_bytes, &data_size_bytes);
  DCHECK(is_attachment_readable);
  DCHECK_EQ(length_bytes, data_size_bytes);

  return content_buf;
}

const DocumentMetadata& PDFiumEngine::GetDocumentMetadata() const {
  DCHECK(document_loaded_);
  return doc_metadata_;
}

int PDFiumEngine::GetNumberOfPages() const {
  return pages_.size();
}

base::Value::List PDFiumEngine::GetBookmarks() {
  base::Value::Dict dict = TraverseBookmarks(nullptr, 0);
  // The root bookmark contains no useful information.
  base::Value::List* children = dict.FindList("children");
  return std::move(*children);
}

base::Value::Dict PDFiumEngine::TraverseBookmarks(FPDF_BOOKMARK bookmark,
                                                  unsigned int depth) {
  base::Value::Dict dict;
  std::u16string title = CallPDFiumWideStringBufferApi(
      base::BindRepeating(&FPDFBookmark_GetTitle, bookmark),
      /*check_expected_size=*/true);
  dict.Set("title", title);

#if BUILDFLAG(ARKWEB_PDF)
  std::string bookmark_id = GenerateBookmarkId();
  dict.Set("id", bookmark_id);
  if (bookmark) {
    bookmark_store_[bookmark_id] = bookmark;
  }
#else
  FPDF_DEST dest = FPDFBookmark_GetDest(doc(), bookmark);
  // Some bookmarks don't have a page to select.
  if (dest) {
    int page_index = FPDFDest_GetDestPageIndex(doc(), dest);
    if (PageIndexInBounds(page_index)) {
      dict.Set("page", page_index);

      std::optional<float> x;
      std::optional<float> y;
      std::optional<float> zoom;
      pages_[page_index]->GetPageDestinationTarget(dest, &x, &y, &zoom);

      if (x) {
        dict.Set("x", static_cast<int>(x.value()));
      }
      if (y) {
        dict.Set("y", static_cast<int>(y.value()));
      }
      if (zoom) {
        dict.Set("zoom", static_cast<double>(zoom.value()));
      }
    }
  } else {
    // Extract URI for bookmarks linking to an external page.
    FPDF_ACTION action = FPDFBookmark_GetAction(bookmark);
    std::string uri = CallPDFiumStringBufferApi(
        base::BindRepeating(&FPDFAction_GetURIPath, doc(), action),
        /*check_expected_size=*/true);
    if (!uri.empty() && base::IsStringUTF8AllowingNoncharacters(uri)) {
      dict.Set("uri", uri);
    }
  }
#endif  // BUILDFLAG(ARKWEB_PDF)

  base::Value::List children;

  // Don't trust PDFium to handle circular bookmarks.
  constexpr unsigned int kMaxDepth = 128;
  if (depth < kMaxDepth) {
    std::set<FPDF_BOOKMARK> seen_bookmarks;
    for (FPDF_BOOKMARK child_bookmark =
             FPDFBookmark_GetFirstChild(doc(), bookmark);
         child_bookmark;
         child_bookmark = FPDFBookmark_GetNextSibling(doc(), child_bookmark)) {
      if (base::Contains(seen_bookmarks, child_bookmark)) {
        break;
      }

      seen_bookmarks.insert(child_bookmark);
      children.Append(TraverseBookmarks(child_bookmark, depth + 1));
    }
  }
  dict.Set("children", std::move(children));
  return dict;
}

void PDFiumEngine::ScrollBasedOnScrollAlignment(
    const gfx::Rect& scroll_rect,
    const AccessibilityScrollAlignment& horizontal_scroll_alignment,
    const AccessibilityScrollAlignment& vertical_scroll_alignment) {
  gfx::Vector2d scroll_offset = GetScreenRect(scroll_rect).OffsetFromOrigin();
  switch (horizontal_scroll_alignment) {
    case AccessibilityScrollAlignment::kRight:
      scroll_offset.set_x(scroll_offset.x() - plugin_size().width());
      break;
    case AccessibilityScrollAlignment::kCenter:
      scroll_offset.set_x(scroll_offset.x() - (plugin_size().width() / 2));
      break;
    case AccessibilityScrollAlignment::kClosestToEdge: {
      scroll_offset.set_x((std::abs(scroll_offset.x()) <=
                           std::abs(scroll_offset.x() - plugin_size().width()))
                              ? scroll_offset.x()
                              : scroll_offset.x() - plugin_size().width());
      break;
    }
    case AccessibilityScrollAlignment::kNone:
      scroll_offset.set_x(0);
      break;
    case AccessibilityScrollAlignment::kLeft:
    case AccessibilityScrollAlignment::kTop:
    case AccessibilityScrollAlignment::kBottom:
    default:
      break;
  }

  switch (vertical_scroll_alignment) {
    case AccessibilityScrollAlignment::kBottom:
      scroll_offset.set_y(scroll_offset.y() - plugin_size().height());
      break;
    case AccessibilityScrollAlignment::kCenter:
      scroll_offset.set_y(scroll_offset.y() - (plugin_size().height() / 2));
      break;
    case AccessibilityScrollAlignment::kClosestToEdge: {
      scroll_offset.set_y((std::abs(scroll_offset.y()) <=
                           std::abs(scroll_offset.y() - plugin_size().height()))
                              ? scroll_offset.y()
                              : scroll_offset.y() - plugin_size().height());
      break;
    }
    case AccessibilityScrollAlignment::kNone:
      scroll_offset.set_y(0);
      break;
    case AccessibilityScrollAlignment::kTop:
    case AccessibilityScrollAlignment::kLeft:
    case AccessibilityScrollAlignment::kRight:
    default:
      break;
  }

  client_->ScrollBy(scroll_offset);
}

void PDFiumEngine::ScrollToGlobalPoint(const gfx::Rect& target_rect,
                                       const gfx::Point& global_point) {
  gfx::Point scroll_offset = GetScreenRect(target_rect).origin();
  client_->ScrollBy(scroll_offset - global_point);
}

std::optional<PDFiumEngine::NamedDestination> PDFiumEngine::GetNamedDestination(
    const std::string& destination) {
  // Look for the destination.
  FPDF_DEST dest = FPDF_GetNamedDestByName(doc(), destination.c_str());
  if (!dest) {
    // Look for a bookmark with the same name.
    std::u16string destination_wide = base::UTF8ToUTF16(destination);
    FPDF_WIDESTRING destination_pdf_wide =
        reinterpret_cast<FPDF_WIDESTRING>(destination_wide.c_str());
    FPDF_BOOKMARK bookmark = FPDFBookmark_Find(doc(), destination_pdf_wide);
    if (bookmark) {
      dest = FPDFBookmark_GetDest(doc(), bookmark);
    }
  }

  if (!dest) {
    return {};
  }

  int page = FPDFDest_GetDestPageIndex(doc(), dest);
  if (!PageIndexInBounds(page)) {
    return {};
  }

  NamedDestination result;
  result.page = page;
  unsigned long view_int =
      FPDFDest_GetView(dest, &result.num_params, result.params.data());

  // FPDFDest_GetView() gets the PDF coordinates directly from the PDF document.
  // The PDF coordinates need to be transformed into screen coordinates before
  // getting sent to the viewport.
  PDFiumPage* page_ptr = pages_[page].get();
  ParamsTransformPageToScreen(view_int, page_ptr, result.params);

  if (view_int == PDFDEST_VIEW_XYZ) {
    result.xyz_params = GetXYZParamsString(dest, page_ptr);
  }

  result.view = ConvertViewIntToViewString(view_int);
  return result;
}

int PDFiumEngine::GetMostVisiblePage() {
  if (in_flight_visible_page_) {
    return *in_flight_visible_page_;
  }

  // We can call GetMostVisiblePage through a callback from PDFium. We have
  // to defer the page deletion otherwise we could potentially delete the page
  // that originated the calling JS request and destroy the objects that are
  // currently being used.
  base::AutoReset<bool> defer_page_unload_guard(&defer_page_unload_, true);
  CalculateVisiblePages();
  return most_visible_page_;
}

gfx::Rect PDFiumEngine::GetPageContentsRect(int page_index) {
  return GetScreenRect(pages_[page_index]->rect());
}

void PDFiumEngine::SetGrayscale(bool grayscale) {
  render_grayscale_ = grayscale;
}

void PDFiumEngine::HandleLongPress(const blink::WebTouchEvent& event) {
  base::AutoReset<bool> handling_long_press_guard(&handling_long_press_, true);

  // Only consider the first touch point.
  DCHECK_GT(event.touches_length, 0u);

#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  // Send a fake mouse down to trigger the multi-click selection code.
  blink::WebMouseEvent mouse_event(blink::WebInputEvent::Type::kMouseDown,
                                   event.GetModifiers(), event.TimeStamp());
  mouse_event.button = blink::WebPointerProperties::Button::kLeft;
  mouse_event.click_count = 2;
  mouse_event.SetPositionInWidget(event.touches[0].PositionInWidget());
#if BUILDFLAG(ARKWEB_PDF)
  OHOS::NWeb::OhosAdapterHelper::GetInstance()
      .GetHiSysEventAdapterInstance()
      .Write(PDF_LONG_PRESS_EVENT,
             OHOS::NWeb::HiSysEventAdapter::EventType::BEHAVIOR,
             {LONG_PRESSED, "true"});
#endif
  OnMouseDown(mouse_event);
}

bool PDFiumEngine::GetPrintScaling() {
  return !!FPDF_VIEWERREF_GetPrintScaling(doc());
}

int PDFiumEngine::GetCopiesToPrint() {
  return FPDF_VIEWERREF_GetNumCopies(doc());
}

printing::mojom::DuplexMode PDFiumEngine::GetDuplexMode() {
  switch (FPDF_VIEWERREF_GetDuplex(doc())) {
    case Simplex:
      return printing::mojom::DuplexMode::kSimplex;
    case DuplexFlipShortEdge:
      return printing::mojom::DuplexMode::kShortEdge;
    case DuplexFlipLongEdge:
      return printing::mojom::DuplexMode::kLongEdge;
    default:
      return printing::mojom::DuplexMode::kUnknownDuplexMode;
  }
}

std::optional<gfx::SizeF> PDFiumEngine::GetPageSizeInPoints(
    int page_index) const {
  FS_SIZEF size_in_points;
  if (!FPDF_GetPageSizeByIndexF(doc(), page_index, &size_in_points)) {
    return std::nullopt;
  }

  return gfx::SizeF(size_in_points.width, size_in_points.height);
}

std::optional<gfx::Size> PDFiumEngine::GetUniformPageSizePoints() {
  if (pages_.empty()) {
    return std::nullopt;
  }

  gfx::Size page_size = GetPageSize(0);
  for (size_t i = 1; i < pages_.size(); ++i) {
    if (page_size != GetPageSize(i)) {
      return std::nullopt;
    }
  }

  // Convert `page_size` back to points.
  return gfx::Size(
      ConvertUnit(page_size.width(), kPixelsPerInch, kPointsPerInch),
      ConvertUnit(page_size.height(), kPixelsPerInch, kPointsPerInch));
}

void PDFiumEngine::AppendBlankPages(size_t num_pages) {
  DCHECK_GT(num_pages, 0U);

  if (!doc()) {
    return;
  }

  selection_.clear();
  pending_pages_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)

  // Delete all pages except the first one.
  while (pages_.size() > 1) {
    pages_.pop_back();
    FPDFPage_Delete(doc(), pages_.size());
  }

  // Create blank pages with the same size as the first page.
  gfx::Size page_0_size = GetPageSize(0);
  float page_0_width_in_points =
      ConvertUnitFloat(page_0_size.width(), kPixelsPerInch, kPointsPerInch);
  float page_0_height_in_points =
      ConvertUnitFloat(page_0_size.height(), kPixelsPerInch, kPointsPerInch);

  for (size_t i = 1; i < num_pages; ++i) {
    {
      // Add a new page to the document, but delete the FPDF_PAGE object.
      ScopedFPDFPage temp_page(FPDFPage_New(doc(), i, page_0_width_in_points,
                                            page_0_height_in_points));
    }

    auto page = std::make_unique<PDFiumPage>(this, i);
    page->MarkAvailable();
    pages_.push_back(std::move(page));
  }

  DCHECK(document_loaded_);
  LoadPageInfo();
}

gfx::Size PDFiumEngine::plugin_size() const {
  if (plugin_size_.has_value()) {
    return plugin_size_.value();
  }
  // TODO(crbug.com/40193305): Fix call sites and inline this getter again.
  DUMP_WILL_BE_NOTREACHED();
  return gfx::Size();
}

void PDFiumEngine::LoadDocument() {
#if BUILDFLAG(ARKWEB_PDF)
  TRACE_EVENT0("media", "PDFiumEngine::LoadDocument");
#endif
  // Check if the document is ready for loading. If it isn't just bail for now,
  // we will call LoadDocument() again later.
  if (!doc() && !doc_loader_->IsDocumentComplete()) {
    FX_DOWNLOADHINTS& download_hints = document_->download_hints();
    if (!FPDFAvail_IsDocAvail(fpdf_availability(), &download_hints)) {
      return;
    }
  }

  // If we're in the middle of getting a password, just return. We will retry
  // loading the document after we get the password anyway.
  if (getting_password_) {
    return;
  }

  bool needs_password = false;
  if (TryLoadingDoc(std::string(), &needs_password)) {
    ContinueLoadingDocument(std::string());
    return;
  }
#if BUILDFLAG(ARKWEB_PDF)
  if (needs_password) {
    GetPasswordAndLoad();
    OHOS::NWeb::OhosAdapterHelper::GetInstance()
        .GetHiSysEventAdapterInstance()
        .Write(PDF_ENCRYPTED_DOCUMENT,
               OHOS::NWeb::HiSysEventAdapter::EventType::BEHAVIOR,
               {DOCUMENT_ENCRYPTED, "true"});

  } else {
    client_->DocumentLoadFailed();
  }
#else
  if (needs_password) {
    GetPasswordAndLoad();
  } else {
    client_->DocumentLoadFailed();
  }
#endif
}

bool PDFiumEngine::TryLoadingDoc(const std::string& password,
                                 bool* needs_password) {
  *needs_password = false;
  if (doc()) {
    // This is probably not necessary, because it should have already been
    // called below in the `doc_` initialization path. However, the previous
    // call may have failed, so call it again for good measure.
    FX_DOWNLOADHINTS& download_hints = document_->download_hints();
    FPDFAvail_IsDocAvail(fpdf_availability(), &download_hints);
    return true;
  }

  if (!password.empty()) {
    password_tries_remaining_--;
  }

  {
    ScopedUnsupportedFeature scoped_unsupported_feature(this);
    document_->LoadDocument(password);
  }

  if (!doc()) {
    if (FPDF_GetLastError() == FPDF_ERR_PASSWORD) {
      *needs_password = true;
    }
    return false;
  }

  // Always call FPDFAvail_IsDocAvail() so PDFium initializes internal data
  // structures.
  FX_DOWNLOADHINTS& download_hints = document_->download_hints();
  FPDFAvail_IsDocAvail(fpdf_availability(), &download_hints);
  return true;
}

void PDFiumEngine::GetPasswordAndLoad() {
  getting_password_ = true;
  DCHECK(!doc());
  DCHECK_EQ(static_cast<unsigned long>(FPDF_ERR_PASSWORD), FPDF_GetLastError());
  client_->GetDocumentPassword(base::BindOnce(
      &PDFiumEngine::OnGetPasswordComplete, weak_factory_.GetWeakPtr()));
}

void PDFiumEngine::OnGetPasswordComplete(const std::string& password) {
  getting_password_ = false;
  ContinueLoadingDocument(password);
}

void PDFiumEngine::ContinueLoadingDocument(const std::string& password) {
  bool needs_password = false;
  bool loaded = TryLoadingDoc(password, &needs_password);
  bool password_incorrect = !loaded && needs_password && !password.empty();
  if (password_incorrect && password_tries_remaining_ > 0) {
    GetPasswordAndLoad();
    return;
  }

  if (!doc()) {
    client_->DocumentLoadFailed();
    return;
  }

  if (FPDFDoc_GetPageMode(doc()) == PAGEMODE_USEOUTLINES) {
    client_->DocumentHasUnsupportedFeature("Bookmarks");
  }

  permissions_ = std::make_unique<PDFiumPermissions>(doc());

  LoadBody();

  if (doc_loader_->IsDocumentComplete()) {
    FinishLoadingDocument();
  }
}

void PDFiumEngine::LoadPageInfo() {
  RefreshCurrentDocumentLayout();

  // TODO(crbug.com/40652841): RefreshCurrentDocumentLayout() should send some
  // sort of "current layout changed" notification, instead of proposing a new
  // layout. Proposals are never rejected currently, so this is OK for now.
  ProposeNextDocumentLayout();
}

void PDFiumEngine::RefreshCurrentDocumentLayout() {
  UpdateDocumentLayout(&layout_);
  if (!layout_.dirty()) {
    return;
  }

  DCHECK_EQ(pages_.size(), layout_.page_count());
  for (size_t i = 0; i < layout_.page_count(); ++i) {
    // TODO(kmoon): This should be the only place that sets `PDFiumPage::rect_`.
    pages_[i]->set_rect(layout_.page_bounds_rect(i));
  }

  layout_.clear_dirty();

  CalculateVisiblePages();
}

void PDFiumEngine::ProposeNextDocumentLayout() {
  DocumentLayout next_layout;
  next_layout.SetOptions(desired_layout_options_);
  UpdateDocumentLayout(&next_layout);

  // The time windows between proposal and application may overlap, so we must
  // always propose a new layout, regardless of the current layout state.
  client_->ProposeDocumentLayout(next_layout);
}

void PDFiumEngine::UpdateDocumentLayout(DocumentLayout* layout) {
  layout->ComputeLayout(LoadPageSizes(layout->options()));
}

std::vector<gfx::Size> PDFiumEngine::LoadPageSizes(
    const DocumentLayout::Options& layout_options) {
  std::vector<gfx::Size> page_sizes;
  if (!doc_loader_) {
    return page_sizes;
  }
  if (pages_.empty() && document_loaded_) {
    return page_sizes;
  }

  pending_pages_.clear();
  size_t new_page_count = FPDF_GetPageCount(doc());

  const bool doc_complete = doc_loader_->IsDocumentComplete();
  const bool is_linear = IsLinearized();
  for (size_t i = 0; i < new_page_count; ++i) {
    // Get page availability. If `document_loaded_` == true and the page is not
    // new, then the page has been constructed already. Get page availability
    // flag from already existing PDFiumPage object. If `document_loaded_` ==
    // false or the page is new, then the page may not be fully loaded yet.
    bool page_available;
    if (document_loaded_ && i < pages_.size()) {
      page_available = pages_[i]->available();
    } else if (is_linear) {
      FX_DOWNLOADHINTS& download_hints = document_->download_hints();
      int linear_page_avail =
          FPDFAvail_IsPageAvail(fpdf_availability(), i, &download_hints);
      page_available = linear_page_avail == PDF_DATA_AVAIL;
    } else {
      page_available = doc_complete;
    }

    // TODO(crbug.com/40652841): It'd be better if page size were independent of
    // layout options, and handled in the layout code.
    gfx::Size size = page_available ? GetPageSizeForLayout(i, layout_options)
                                    : default_page_size_;
    page_sizes.push_back(size +
                         GetInsets(layout_options, i, new_page_count).size());
  }

  // Add new pages. If `document_loaded_` == false, do not mark page as
  // available even if `doc_complete` is true because FPDFAvail_IsPageAvail()
  // still has to be called for this page, which will be done in
  // FinishLoadingDocument().
  for (size_t i = pages_.size(); i < new_page_count; ++i) {
    auto page = std::make_unique<PDFiumPage>(this, i);
    if (document_loaded_ &&
        FPDFAvail_IsPageAvail(fpdf_availability(), i, nullptr)) {
      page->MarkAvailable();
    }
    pages_.push_back(std::move(page));
  }

  // Remove pages that do not exist anymore.
  if (pages_.size() > new_page_count) {
    for (size_t i = new_page_count; i < pages_.size(); ++i) {
      pages_[i]->Unload();
    }

    pages_.resize(new_page_count);
  }

  return page_sizes;
}

void PDFiumEngine::LoadBody() {
  DCHECK(doc());
  if (doc_loader_->IsDocumentComplete()) {
    LoadForm();
  } else if (IsLinearized() && FPDF_GetPageCount(doc()) == 1) {
    // If we have only one page we should load form first, because it may be an
    // XFA document. And after loading form the page count and its contents may
    // be changed.
    LoadForm();
    if (document_->form_status() == PDF_FORM_NOTAVAIL) {
      return;
    }
  }
  LoadPages();
}

void PDFiumEngine::LoadPages() {
  if (pages_.empty()) {
    if (!doc_loader_->IsDocumentComplete()) {
      // Check if the first page is available.  In a linearized PDF, that is not
      // always page 0.  Doing this gives us the default page size, since when
      // the document is available, the first page is available as well.
      CheckPageAvailable(FPDFAvail_GetFirstPageNum(doc()), &pending_pages_);
    }
    DCHECK(!document_loaded_);
    LoadPageInfo();
  }
}

void PDFiumEngine::LoadForm() {
  if (form()) {
    return;
  }

  DCHECK(doc());
  document_->SetFormStatus();
  if (document_->form_status() != PDF_FORM_NOTAVAIL ||
      doc_loader_->IsDocumentComplete()) {
    {
      ScopedUnsupportedFeature scoped_unsupported_feature(this);
      document_->InitializeForm(&form_filler_);
    }

    if (form_filler_.script_option() ==
        PDFiumFormFiller::ScriptOption::kJavaScriptAndXFA) {
      FPDF_LoadXFA(doc());
    }
    FPDF_SetFormFieldHighlightColor(form(), FPDF_FORMFIELD_UNKNOWN,
                                    kFormHighlightColor);
    SetFormHighlight(true);

    if (!client_->IsPrintPreview()) {
      static constexpr FPDF_ANNOTATION_SUBTYPE kFocusableAnnotSubtypes[] = {
          FPDF_ANNOT_LINK, FPDF_ANNOT_HIGHLIGHT, FPDF_ANNOT_WIDGET};
      FPDF_BOOL ret = FPDFAnnot_SetFocusableSubtypes(
          form(), kFocusableAnnotSubtypes, std::size(kFocusableAnnotSubtypes));
      DCHECK(ret);
    }
  }
}

bool PDFiumEngine::IsLinearized() {
  DCHECK(fpdf_availability());
  return FPDFAvail_IsLinearized(fpdf_availability()) == PDF_LINEARIZED;
}

void PDFiumEngine::CalculateVisiblePages() {
  if (!plugin_size_.has_value()) {
    return;
  }

  // Early return if the PDF isn't being loaded or if we don't have the document
  // info yet. The latter is important because otherwise as the PDF is being
  // initialized by the renderer there could be races that call this method
  // before we get the initial network responses. The document loader depends on
  // the list of pending requests to be valid for progressive loading to
  // function.
  if (!doc_loader_ || pages_.empty()) {
    return;
  }
  // Clear pending requests queue, since it may contain requests to the pages
  // that are already invisible (after scrolling for example).
  pending_pages_.clear();
  doc_loader_->ClearPendingRequests();

  visible_pages_.clear();
  gfx::Rect visible_rect(plugin_size());
  for (size_t i = 0; i < pages_.size(); ++i) {
    // Check an entire PageScreenRect, since we might need to repaint side
    // borders and shadows even if the page itself is not visible.
    // For example, when user use pdf with different page sizes and zoomed in
    // outside page area.
    if (visible_rect.Intersects(GetPageScreenRect(i))) {
      visible_pages_.push_back(i);
      CheckPageAvailable(i, &pending_pages_);
    } else {
      // Need to unload pages when we're not using them, since some PDFs use a
      // lot of memory.  See http://crbug.com/48791
      if (defer_page_unload_) {
        deferred_page_unloads_.push_back(i);
      } else {
        pages_[i]->Unload();
      }
    }
  }

  // Any pending highlighting of form fields will be invalid since these are in
  // screen coordinates.
  form_highlights_.clear();

  std::vector<draw_utils::IndexedPage> visible_pages_rects;
  visible_pages_rects.reserve(visible_pages_.size());
  for (uint32_t visible_page_index : visible_pages_) {
    visible_pages_rects.emplace_back(visible_page_index,
                                     pages_[visible_page_index]->rect());
  }

  int most_visible_page =
      draw_utils::GetMostVisiblePage(visible_pages_rects, GetVisibleRect());
  SetCurrentPage(most_visible_page);
}

bool PDFiumEngine::IsPageVisible(int page_index) const {
  // CalculateVisiblePages() must have been called first to populate
  // `visible_pages_`. Otherwise, this will always return false.
  return base::Contains(visible_pages_, page_index);
}

void PDFiumEngine::ScrollToPage(int page) {
  if (!PageIndexInBounds(page)) {
    return;
  }

  in_flight_visible_page_ = page;
  client_->ScrollToPage(page);
}

bool PDFiumEngine::CheckPageAvailable(uint32_t index,
                                      std::vector<uint32_t>* pending) {
  if (!doc()) {
    return false;
  }

  const size_t num_pages = pages_.size();
  if (index < num_pages && pages_[index]->available()) {
    return true;
  }

  FX_DOWNLOADHINTS& download_hints = document_->download_hints();
  if (!FPDFAvail_IsPageAvail(fpdf_availability(), index, &download_hints)) {
    if (!base::Contains(*pending, index)) {
      pending->push_back(index);
    }
    return false;
  }

  if (index < num_pages) {
    pages_[index]->MarkAvailable();
  }
  if (default_page_size_.IsEmpty()) {
    default_page_size_ = GetPageSize(index);
  }
  return true;
}

gfx::Size PDFiumEngine::GetPageSize(int index) {
  return GetPageSizeForLayout(index, layout_.options());
}

gfx::Size PDFiumEngine::GetPageSizeForLayout(
    int index,
    const DocumentLayout::Options& layout_options) {
  std::optional<gfx::SizeF> size_in_points = GetPageSizeInPoints(index);
  if (!size_in_points.has_value()) {
    return gfx::Size();
  }

  int width_in_pixels = static_cast<int>(ConvertUnitFloat(
      size_in_points.value().width(), kPointsPerInch, kPixelsPerInch));
  int height_in_pixels = static_cast<int>(ConvertUnitFloat(
      size_in_points.value().height(), kPointsPerInch, kPixelsPerInch));

  if (IsTransposedPageOrientation(layout_options.default_page_orientation())) {
    // Rotated 90 degrees: swap axes.
    std::swap(width_in_pixels, height_in_pixels);
  }

  return gfx::Size(width_in_pixels, height_in_pixels);
}

gfx::Insets PDFiumEngine::GetInsets(
    const DocumentLayout::Options& layout_options,
    size_t page_index,
    size_t num_of_pages) const {
  DCHECK_LT(page_index, num_of_pages);

  if (layout_options.page_spread() == DocumentLayout::PageSpread::kTwoUpOdd) {
    return draw_utils::GetPageInsetsForTwoUpView(
        page_index, num_of_pages, DocumentLayout::kSingleViewInsets,
        DocumentLayout::kHorizontalSeparator);
  }

  return DocumentLayout::kSingleViewInsets;
}

std::optional<size_t> PDFiumEngine::GetAdjacentPageIndexForTwoUpView(
    size_t page_index,
    size_t num_of_pages) const {
  DCHECK_LT(page_index, num_of_pages);

  if (layout_.options().page_spread() == DocumentLayout::PageSpread::kOneUp) {
    return std::nullopt;
  }

  int adjacent_page_offset = page_index % 2 ? -1 : 1;
  size_t adjacent_page_index = page_index + adjacent_page_offset;
  if (adjacent_page_index >= num_of_pages) {
    return std::nullopt;
  }

  return adjacent_page_index;
}

size_t PDFiumEngine::StartPaint(uint32_t page_index, const gfx::Rect& dirty) {
  // For the first time we hit paint, do nothing and just record the paint for
  // the next callback.  This keeps the UI responsive in case the user is doing
  // a lot of scrolling.
  progressive_paints_.emplace_back(page_index, dirty);
  return progressive_paints_.size() - 1;
}

bool PDFiumEngine::ContinuePaint(size_t progressive_index,
                                 SkBitmap& image_data) {
  CHECK_LT(progressive_index, progressive_paints_.size());
  auto& paint = progressive_paints_[progressive_index];

  last_progressive_start_time_ = base::Time::Now();

  CHECK(PageIndexInBounds(paint.page_index()));
  FPDF_PAGE page = pages_[paint.page_index()]->GetPage();
  if (paint.bitmap()) {
    return FPDF_RenderPage_Continue(page, this) != FPDF_RENDER_TOBECONTINUED;
  }

  const gfx::Rect& dirty = paint.rect();
  const bool has_alpha = !!FPDFPage_HasTransparency(page);
  ScopedFPDFBitmap new_bitmap = CreateBitmap(dirty, has_alpha, image_data);
  FPDF_BITMAP new_bitmap_ptr = new_bitmap.get();
  paint.SetBitmapAndImageData(std::move(new_bitmap), image_data);

  const gfx::Rect pdfium_rect = GetPDFiumRect(paint.page_index(), dirty);
  // When `has_alpha` is true, use a transparent bitmap to render correctly.
  // If the bitmap was painted white, then certain blend operations would
  // blend into the white color and draw incorrectly. Instead, PaintManager
  // will draw the white page under this bitmap.
  const uint32_t fill_color = has_alpha ? 0x00000000 : 0xFFFFFFFF;
  FPDFBitmap_FillRect(new_bitmap_ptr, pdfium_rect.x(), pdfium_rect.y(),
                      pdfium_rect.width(), pdfium_rect.height(), fill_color);

  return FPDF_RenderPageBitmap_Start(
             new_bitmap_ptr, page, pdfium_rect.x(), pdfium_rect.y(),
             pdfium_rect.width(), pdfium_rect.height(),
             GetClockwiseRotationSteps(GetCurrentOrientation()),
             GetRenderingFlags(), this) != FPDF_RENDER_TOBECONTINUED;
}

void PDFiumEngine::FinishPaint(size_t progressive_index, SkBitmap& image_data) {
  CHECK_LT(progressive_index, progressive_paints_.size());

  int page_index = progressive_paints_[progressive_index].page_index();
  gfx::Rect dirty_in_screen = progressive_paints_[progressive_index].rect();

  FPDF_BITMAP bitmap = progressive_paints_[progressive_index].bitmap();
  const gfx::Rect pdfium_rect = GetPDFiumRect(page_index, dirty_in_screen);

  // Draw the forms.
  FPDF_FFLDraw(form(), bitmap, pages_[page_index]->GetPage(), pdfium_rect.x(),
               pdfium_rect.y(), pdfium_rect.width(), pdfium_rect.height(),
               GetClockwiseRotationSteps(GetCurrentOrientation()),
               GetRenderingFlags());

  FillPageSides(progressive_index);

  // Paint the page shadows.
  PaintPageShadow(progressive_index, image_data);

  DrawCaret(progressive_index, image_data);
  DrawSelections(progressive_index, image_data);
  form_highlights_.clear();

  FPDF_RenderPage_Close(pages_[page_index]->GetPage());
  progressive_paints_.erase(progressive_paints_.begin() + progressive_index);

  MaybeRequestPendingThumbnail(page_index);
}

void PDFiumEngine::CancelPaints() {
  for (const auto& paint : progressive_paints_) {
    FPDF_RenderPage_Close(pages_[paint.page_index()]->GetPage());
  }

  progressive_paints_.clear();
}

void PDFiumEngine::FillPageSides(int progressive_index) {
  DCHECK_GE(progressive_index, 0);
  DCHECK_LT(static_cast<size_t>(progressive_index), progressive_paints_.size());

  int page_index = progressive_paints_[progressive_index].page_index();
  gfx::Rect dirty_in_screen = progressive_paints_[progressive_index].rect();
  FPDF_BITMAP bitmap = progressive_paints_[progressive_index].bitmap();
  gfx::Insets insets = GetInsets(layout_.options(), page_index, pages_.size());

  gfx::Rect page_rect = pages_[page_index]->rect();
  const bool is_two_up_view =
      layout_.options().page_spread() == DocumentLayout::PageSpread::kTwoUpOdd;
  if (page_rect.x() > 0 && (!is_two_up_view || page_index % 2 == 0)) {
    // If in two-up view, only need to draw the left empty space for left pages
    // since the gap between the left and right page will be drawn by the left
    // page.
    gfx::Rect left_in_screen = GetScreenRect(draw_utils::GetLeftFillRect(
        page_rect, insets, DocumentLayout::kBottomSeparator));
    left_in_screen.Intersect(dirty_in_screen);

    FPDFBitmap_FillRect(bitmap, left_in_screen.x() - dirty_in_screen.x(),
                        left_in_screen.y() - dirty_in_screen.y(),
                        left_in_screen.width(), left_in_screen.height(),
                        client_->GetBackgroundColor());
  }

  if (page_rect.right() < layout_.size().width()) {
    gfx::Rect right_in_screen = GetScreenRect(
        draw_utils::GetRightFillRect(page_rect, insets, layout_.size().width(),
                                     DocumentLayout::kBottomSeparator));
    right_in_screen.Intersect(dirty_in_screen);

    FPDFBitmap_FillRect(bitmap, right_in_screen.x() - dirty_in_screen.x(),
                        right_in_screen.y() - dirty_in_screen.y(),
                        right_in_screen.width(), right_in_screen.height(),
                        client_->GetBackgroundColor());
  }

  gfx::Rect bottom_in_screen;
  if (is_two_up_view) {
    gfx::Rect page_in_screen = GetScreenRect(page_rect);
    bottom_in_screen = draw_utils::GetBottomGapBetweenRects(
        page_in_screen.bottom(), dirty_in_screen);

    if (page_index % 2 == 1) {
      draw_utils::AdjustBottomGapForRightSidePage(page_in_screen.x(),
                                                  &bottom_in_screen);
    }

    bottom_in_screen.Intersect(dirty_in_screen);
  } else {
    bottom_in_screen = GetScreenRect(draw_utils::GetBottomFillRect(
        page_rect, insets, DocumentLayout::kBottomSeparator));
    bottom_in_screen.Intersect(dirty_in_screen);
  }

  FPDFBitmap_FillRect(bitmap, bottom_in_screen.x() - dirty_in_screen.x(),
                      bottom_in_screen.y() - dirty_in_screen.y(),
                      bottom_in_screen.width(), bottom_in_screen.height(),
                      client_->GetBackgroundColor());
}

void PDFiumEngine::PaintPageShadow(size_t progressive_index,
                                   SkBitmap& image_data) {
  CHECK_LT(progressive_index, progressive_paints_.size());

  int page_index = progressive_paints_[progressive_index].page_index();
  gfx::Rect dirty_in_screen = progressive_paints_[progressive_index].rect();
  gfx::Rect shadow_rect(pages_[page_index]->rect());
  gfx::Insets insets = GetInsets(layout_.options(), page_index, pages_.size());
  shadow_rect.Inset(ScaleToCeiledInsets(insets, -1));

  // Due to the rounding errors of GetScreenRect(), it is possible to get
  // different size shadows on the left and right sides even they are defined
  // the same. To fix this issue, calculate the shadow rect and then shrink it
  // by the size of the shadows.
  shadow_rect = GetScreenRect(shadow_rect);

  gfx::Rect page_rect = shadow_rect;
  page_rect.Inset(ScaleToCeiledInsets(insets, current_zoom_));
  DrawPageShadow(page_rect, shadow_rect, dirty_in_screen, image_data);
}

void PDFiumEngine::DrawCaret(size_t progressive_index,
                             SkBitmap& image_data) const {
  if (!caret_) {
    return;
  }

  CHECK_LT(progressive_index, progressive_paints_.size());

  const gfx::Rect& dirty_in_screen =
      progressive_paints_[progressive_index].rect();

  const std::optional<RegionData> region =
      GetRegion(dirty_in_screen.origin(), image_data);
  if (!region.has_value()) {
    return;
  }

  caret_->MaybeDrawCaret(region.value(), dirty_in_screen);
}

void PDFiumEngine::DrawSelections(size_t progressive_index,
                                  SkBitmap& image_data) const {
  CHECK_LT(progressive_index, progressive_paints_.size());

  uint32_t page_index = progressive_paints_[progressive_index].page_index();
  gfx::Rect dirty_in_screen = progressive_paints_[progressive_index].rect();

  const std::optional<RegionData> region =
      GetRegion(dirty_in_screen.origin(), image_data);
  if (!region.has_value()) {
    return;
  }

  // Draw the find-in-page selection.
  std::vector<gfx::Rect> highlighted_rects;
  gfx::Rect visible_rect = GetVisibleRect();
  const PDFiumRange* find_selection = GetFindSelection();
  if (find_selection && find_selection->page_index() == page_index) {
    DrawHighlightOnPage(*find_selection, dirty_in_screen, visible_rect,
                        region.value(), kHighlightColor, highlighted_rects);
  }

#if BUILDFLAG(ENABLE_PDF_INK2)
  // Ink2 ignores all other selections.
  if (client_->IsInAnnotationMode()) {
    return;
  }
#endif  // BUILDFLAG(ENABLE_PDF_INK2)

  // Draw text selections next.
  for (const auto& range : selection_) {
    if (range.page_index() != page_index) {
      continue;
    }

    DrawHighlightOnPage(range, dirty_in_screen, visible_rect, region.value(),
                        kHighlightColor, highlighted_rects);
  }

  // Draw text fragment and form highlights last. This ensures that the previous
  // selection highlights are drawn on top.
  for (const auto& range : text_fragment_highlights_) {
    if (range.page_index() != page_index) {
      continue;
    }

    DrawHighlightOnPage(range, dirty_in_screen, visible_rect, region.value(),
                        shared_highlighting::kFragmentTextBackgroundColorARGB,
                        highlighted_rects);
  }

  for (const auto& highlight : form_highlights_) {
    gfx::Rect visible_selection =
        gfx::IntersectRects(highlight, dirty_in_screen);
    if (visible_selection.IsEmpty()) {
      continue;
    }

    visible_selection.Offset(-dirty_in_screen.OffsetFromOrigin());
    Highlight(region.value(), visible_selection, kHighlightColor,
              highlighted_rects);
  }
}

void PDFiumEngine::PaintUnavailablePage(int page_index,
                                        const gfx::Rect& dirty,
                                        SkBitmap& image_data) {
  const gfx::Rect pdfium_rect = GetPDFiumRect(page_index, dirty);
  ScopedFPDFBitmap bitmap(CreateBitmap(dirty, /*has_alpha=*/false, image_data));
  FPDFBitmap_FillRect(bitmap.get(), pdfium_rect.x(), pdfium_rect.y(),
                      pdfium_rect.width(), pdfium_rect.height(),
                      kPendingPageColor);

  gfx::Rect loading_text_in_screen(
      pages_[page_index]->rect().width() / 2,
      pages_[page_index]->rect().y() + kLoadingTextVerticalOffset, 0, 0);
  loading_text_in_screen = GetScreenRect(loading_text_in_screen);
}

std::optional<size_t> PDFiumEngine::GetProgressiveIndex(
    uint32_t page_index) const {
  for (size_t i = 0; i < progressive_paints_.size(); ++i) {
    if (progressive_paints_[i].page_index() == page_index) {
      return i;
    }
  }
  return std::nullopt;
}

ScopedFPDFBitmap PDFiumEngine::CreateBitmap(const gfx::Rect& rect,
                                            bool has_alpha,
                                            SkBitmap& image_data) const {
  const std::optional<RegionData> region = GetRegion(rect.origin(), image_data);
  if (!region.has_value()) {
    return nullptr;
  }
  int format = has_alpha ? FPDFBitmap_BGRA : FPDFBitmap_BGRx;
  return ScopedFPDFBitmap(FPDFBitmap_CreateEx(
      rect.width(), rect.height(), format, region.value().buffer.data(),
      base::checked_cast<int>(region.value().stride)));
}

gfx::Rect PDFiumEngine::GetPDFiumRect(int page_index,
                                      const gfx::Rect& rect) const {
  gfx::Rect page_rect = GetScreenRect(pages_[page_index]->rect());
  page_rect.Offset(-rect.x(), -rect.y());
  return page_rect;
}

int PDFiumEngine::GetRenderingFlags() const {
  int flags = FPDF_LCD_TEXT;
#if BUILDFLAG(ARKWEB_PDF)
  flags |= FPDF_REVERSE_BYTE_ORDER;
#endif
  if (render_grayscale_) {
    flags |= FPDF_GRAYSCALE;
  }
  if (client_->IsPrintPreview()) {
    flags |= FPDF_PRINTING;
  }
  if (render_annots_) {
    flags |= FPDF_ANNOT;
  }
  return flags;
}

gfx::Rect PDFiumEngine::GetVisibleRect() const {
  gfx::Rect rv;
  rv.set_x(static_cast<int>(position_.x() / current_zoom_));
  rv.set_y(static_cast<int>(position_.y() / current_zoom_));

  // TODO(crbug.com/40193305): Can we avoid the need for .has_value()?
  if (plugin_size_.has_value()) {
    rv.set_width(static_cast<int>(ceil(plugin_size_->width() / current_zoom_)));
    rv.set_height(
        static_cast<int>(ceil(plugin_size_->height() / current_zoom_)));
  }

  return rv;
}

gfx::Rect PDFiumEngine::GetPageScreenRect(int page_index) const {
  gfx::Rect page_rect = pages_[page_index]->rect();
  gfx::Insets insets = GetInsets(layout_.options(), page_index, pages_.size());

  int max_page_height = page_rect.height();
  std::optional<size_t> adjacent_page_index =
      GetAdjacentPageIndexForTwoUpView(page_index, pages_.size());
  if (adjacent_page_index.has_value()) {
    max_page_height = std::max(
        max_page_height, pages_[adjacent_page_index.value()]->rect().height());
  }

  return GetScreenRect(draw_utils::GetSurroundingRect(
      page_rect.y(), max_page_height, insets, layout_.size().width(),
      DocumentLayout::kBottomSeparator));
}

gfx::Rect PDFiumEngine::GetScreenRect(const gfx::Rect& rect) const {
  return draw_utils::GetScreenRect(rect, position_, current_zoom_);
}

std::vector<gfx::Rect> PDFiumEngine::GetNoTextPageScreenRectsForCaret(
    PDFiumPage* page) const {
  // TODO(crbug.com/437807125): Determine default caret offset and size.
  static constexpr float kCaretOffset = 10.0f;
  static constexpr float kCaretSize = 12.0f;

  const PdfRect page_bounds = GetPageBoundingBox(page->GetPage()).value();
  const float caret_left = page_bounds.left() + kCaretOffset;
  const float caret_top = page_bounds.top() - kCaretOffset;
  const PdfRect caret_rect(/*left=*/caret_left,
                           /*bottom=*/caret_top - kCaretSize,
                           /*right=*/caret_left + kCaretSize,
                           /*top=*/caret_top);

  // The PDF page is too small to display the default caret size.
  if (caret_rect.right() >= page_bounds.right() ||
      caret_rect.top() >= page_bounds.top()) {
    return {};
  }

  return {page->PageToScreen(GetVisibleRect().origin(), current_zoom_,
                             caret_rect, GetCurrentOrientation())};
}

void PDFiumEngine::Highlight(const RegionData& region,
                             const gfx::Rect& rect,
                             SkColor color,
                             std::vector<gfx::Rect>& highlighted_rects) const {
  gfx::Rect new_rect = rect;
  for (const auto& highlighted : highlighted_rects) {
    new_rect.Subtract(highlighted);
  }
  if (new_rect.IsEmpty()) {
    return;
  }

  std::vector<size_t> overlapping_rect_indices;
  for (size_t i = 0; i < highlighted_rects.size(); ++i) {
    if (new_rect.Intersects((highlighted_rects)[i])) {
      overlapping_rect_indices.push_back(i);
    }
  }

  highlighted_rects.push_back(new_rect);
  int l = new_rect.x();
  int t = new_rect.y();
  int w = new_rect.width();
  int h = new_rect.height();
  SkColor4f color_f = SkColor4f::FromColor(color);
  for (int y = t; y < t + h; ++y) {
    base::span<uint8_t> row =
        region.buffer.subspan(y * region.stride, region.stride);
    for (int x = l; x < l + w; ++x) {
      bool overlaps = false;
      for (size_t i : overlapping_rect_indices) {
        const auto& highlighted = (highlighted_rects)[i];
        if (highlighted.Contains(x, y)) {
          overlaps = true;
          break;
        }
      }
      if (overlaps) {
        continue;
      }

      size_t pixel_index = x * 4;
      if (pixel_index + 2 < row.size()) {
        row[pixel_index] = static_cast<uint8_t>(row[pixel_index] * color_f.fB);
        row[pixel_index + 1] =
            static_cast<uint8_t>(row[pixel_index + 1] * color_f.fG);
        row[pixel_index + 2] =
            static_cast<uint8_t>(row[pixel_index + 2] * color_f.fR);
      }
    }
  }
}

PDFiumEngine::ChangeInvalidator::ChangeInvalidator(PDFiumEngine* engine)
    : engine_(engine), previous_origin_(engine_->GetVisibleRect().origin()) {}
PDFiumEngine::ChangeInvalidator::~ChangeInvalidator() = default;

std::vector<gfx::Rect>
PDFiumEngine::ChangeInvalidator::GetVisibleScreenRectsFromRanges(
    base::span<const PDFiumRange> ranges) const {
  std::vector<gfx::Rect> rects;
  gfx::Point visible_point = engine_->GetVisibleRect().origin();
  for (const auto& range : ranges) {
    // Exclude selections on pages that's not currently visible.
    if (!engine_->IsPageVisible(range.page_index())) {
      continue;
    }

    const std::vector<gfx::Rect>& screen_rects =
        range.GetScreenRects(visible_point, engine_->current_zoom_,
                             engine_->GetCurrentOrientation());
    rects.insert(rects.end(), screen_rects.begin(), screen_rects.end());
  }
  return rects;
}

bool PDFiumEngine::ChangeInvalidator::Invalidate(
    base::span<const gfx::Rect> screen_rects) {
  bool invalidated = false;
  for (const auto& rect : screen_rects) {
    if (rect.IsEmpty()) {
      continue;
    }

    gfx::Rect expanded_rect = rect;
    expanded_rect.Outset(1);
    engine_->client_->Invalidate(expanded_rect);
    invalidated = true;
  }
  return invalidated;
}

bool PDFiumEngine::ChangeInvalidator::InvalidateChangesOnDestruct() {
  // Offset the old selections if the document scrolled since we recorded them.
  gfx::Vector2d offset = previous_origin_ - engine_->GetVisibleRect().origin();
  for (auto& previous_rect : previous_rects_) {
    previous_rect.Offset(offset);
  }

  std::vector<gfx::Rect> new_rects = GetVisibleChangeRects();
  for (auto& new_rect : new_rects) {
    for (auto& previous_rect : previous_rects_) {
      if (!previous_rect.IsEmpty() && new_rect == previous_rect) {
        // Rectangle was selected before and after, so no need to invalidate it.
        // Mark the rectangles by setting them to empty.
        new_rect = previous_rect = gfx::Rect();
        break;
      }
    }
  }

  bool invalidated = Invalidate(previous_rects_);
  invalidated |= Invalidate(new_rects);
  return invalidated;
}

PDFiumEngine::SelectionChangeInvalidator::SelectionChangeInvalidator(
    PDFiumEngine* engine)
    : ChangeInvalidator(engine) {
  previous_rects_ = GetVisibleChangeRects();
}

PDFiumEngine::SelectionChangeInvalidator::~SelectionChangeInvalidator() {
  if (InvalidateChangesOnDestruct()) {
    engine_->OnSelectionTextChanged();
    engine_->OnSelectionPositionChanged();
  }
}

std::vector<gfx::Rect>
PDFiumEngine::SelectionChangeInvalidator::GetVisibleChangeRects() const {
  return GetVisibleScreenRectsFromRanges(engine_->selection_);
}

PDFiumEngine::FindResultChangeInvalidator::FindResultChangeInvalidator(
    PDFiumEngine* engine)
    : ChangeInvalidator(engine) {
  previous_rects_ = GetVisibleChangeRects();
}

PDFiumEngine::FindResultChangeInvalidator::~FindResultChangeInvalidator() {
  InvalidateChangesOnDestruct();
}

std::vector<gfx::Rect>
PDFiumEngine::FindResultChangeInvalidator::GetVisibleChangeRects() const {
  const PDFiumRange* find_selection = engine_->GetFindSelection();
  return find_selection ? GetVisibleScreenRectsFromRanges(
                              base::span_from_ref(*find_selection))
                        : std::vector<gfx::Rect>();
}

PDFiumEngine::HighlightChangeInvalidator::HighlightChangeInvalidator(
    PDFiumEngine* engine)
    : ChangeInvalidator(engine) {
  previous_rects_ = GetVisibleChangeRects();
}

PDFiumEngine::HighlightChangeInvalidator::~HighlightChangeInvalidator() {
  InvalidateChangesOnDestruct();
}

std::vector<gfx::Rect>
PDFiumEngine::HighlightChangeInvalidator::GetVisibleChangeRects() const {
  return GetVisibleScreenRectsFromRanges(engine_->text_fragment_highlights_);
}

PDFiumEngine::MouseDownState::MouseDownState(
    const PDFiumPage::Area& area,
    const PDFiumPage::LinkTarget& target)
    : area_(area), target_(target) {}

PDFiumEngine::MouseDownState::~MouseDownState() = default;

void PDFiumEngine::MouseDownState::Set(const PDFiumPage::Area& area,
                                       const PDFiumPage::LinkTarget& target) {
  area_ = area;
  target_ = target;
}

void PDFiumEngine::MouseDownState::Reset() {
  area_ = PDFiumPage::NONSELECTABLE_AREA;
  target_ = PDFiumPage::LinkTarget();
}

bool PDFiumEngine::MouseDownState::Matches(
    const PDFiumPage::Area& area,
    const PDFiumPage::LinkTarget& target) const {
  if (area_ != area) {
    return false;
  }

  if (area == PDFiumPage::WEBLINK_AREA) {
    return target_.url == target.url;
  }

  if (area == PDFiumPage::DOCLINK_AREA) {
    return target_.page == target.page;
  }

  return true;
}

gfx::PointF PDFiumEngine::DeviceToPdf(uint32_t page_index,
                                      const gfx::PointF& device_point) {
  gfx::Point screen_point = DeviceToScreen(device_point);

  PDFiumPage* page = pages_[page_index].get();
  const gfx::Rect& page_rect = page->rect();
  screen_point -= page_rect.OffsetFromOrigin();

  double page_x = 0;
  double page_y = 0;
  FPDF_BOOL ret = FPDF_DeviceToPage(
      page->GetPage(), 0, 0, page_rect.width(), page_rect.height(),
      GetClockwiseRotationSteps(GetCurrentOrientation()), screen_point.x(),
      screen_point.y(), &page_x, &page_y);
  DCHECK(ret);
  return gfx::PointF(page_x, page_y);
}

gfx::Point PDFiumEngine::DeviceToScreen(const gfx::PointF& device_point) const {
  return {static_cast<int>((device_point.x() + position_.x()) / current_zoom_),
          static_cast<int>((device_point.y() + position_.y()) / current_zoom_)};
}

int PDFiumEngine::GetVisiblePageIndex(FPDF_PAGE page) {
  // Copy `visible_pages_` since it can change as a result of loading the page
  // in GetPage(). See https://crbug.com/822091.
  std::vector<uint32_t> visible_pages_copy(visible_pages_);
  for (uint32_t page_index : visible_pages_copy) {
    if (pages_[page_index]->GetPage() == page) {
      return page_index;
    }
  }
  return -1;
}

void PDFiumEngine::SetCurrentPage(int index) {
  in_flight_visible_page_.reset();

  if (index == most_visible_page_ || !form()) {
    return;
  }

  if (most_visible_page_ != -1 && called_do_document_action_) {
    FPDF_PAGE old_page = pages_[most_visible_page_]->GetPage();
    FORM_DoPageAAction(old_page, form(), FPDFPAGE_AACTION_CLOSE);
  }
  most_visible_page_ = index;
  if (most_visible_page_ != -1 && called_do_document_action_) {
    FPDF_PAGE new_page = pages_[most_visible_page_]->GetPage();
    FORM_DoPageAAction(new_page, form(), FPDFPAGE_AACTION_OPEN);
  }
}

void PDFiumEngine::DrawPageShadow(const gfx::Rect& page_rc,
                                  const gfx::Rect& shadow_rc,
                                  const gfx::Rect& clip_rc,
                                  SkBitmap& image_data) {
  gfx::Rect page_rect(page_rc);
  page_rect.Offset(page_offset_);

  gfx::Rect shadow_rect(shadow_rc);
  shadow_rect.Offset(page_offset_);

  gfx::Rect clip_rect(clip_rc);
  clip_rect.Offset(page_offset_);

  // Page drop shadow parameters.
  constexpr double factor = 0.5;
  uint32_t depth = std::max({page_rect.x() - shadow_rect.x(),
                             page_rect.y() - shadow_rect.y(),
                             shadow_rect.right() - page_rect.right(),
                             shadow_rect.bottom() - page_rect.bottom()});
  depth = static_cast<uint32_t>(depth * 1.5) + 1;

  // We need to check depth only to verify our copy of shadow matrix is correct.
  if (!page_shadow_ || page_shadow_->depth() != depth) {
    page_shadow_ = std::make_unique<draw_utils::ShadowMatrix>(
        depth, factor, client_->GetBackgroundColor());
  }

  DCHECK(!image_data.isNull());
  DrawShadow(image_data, shadow_rect, page_rect, clip_rect, *page_shadow_);
}

void PDFiumEngine::DrawHighlightOnPage(
    const PDFiumRange& range,
    const gfx::Rect& dirty_in_screen,
    const gfx::Rect& visible_rect,
    const RegionData& region,
    SkColor color,
    std::vector<gfx::Rect>& highlighted_rects) const {
  const std::vector<gfx::Rect>& rects = range.GetScreenRects(
      visible_rect.origin(), current_zoom_, GetCurrentOrientation());
  for (const auto& rect : rects) {
    gfx::Rect visible_selection = gfx::IntersectRects(rect, dirty_in_screen);
    if (visible_selection.IsEmpty()) {
      continue;
    }

    visible_selection.Offset(-dirty_in_screen.OffsetFromOrigin());
    Highlight(region, visible_selection, color, highlighted_rects);
  }
}

std::optional<RegionData> PDFiumEngine::GetRegion(const gfx::Point& location,
                                                  SkBitmap& image_data) const {
  if (image_data.isNull()) {
    DCHECK(plugin_size().IsEmpty());
    return std::nullopt;
  }

  uint8_t* buffer = static_cast<uint8_t*>(image_data.getPixels());
  if (!buffer) {
    return std::nullopt;
  }

  // TODO: update this when we support BIDI and scrollbars can be on the left.
  if (!gfx::Rect(plugin_size()).Contains(location)) {
    return std::nullopt;
  }

  size_t stride = image_data.rowBytes();
  size_t x_offset = location.x() + page_offset_.x();
  size_t offset = location.y() * stride + x_offset * 4;
  // SAFETY: Skia guarantees image_data.height() * image_data.rowBytes() is the
  // exact size of the allocated pixel buffer, including row padding. However,
  // Skia does not have a span-based API for this.
  // TODO(crbug.com/357905831): Switch to SkSpan when possible.
  UNSAFE_BUFFERS(
      base::span<uint8_t> buffer_span(buffer, image_data.height() * stride));
  return RegionData(buffer_span.subspan(offset), stride);
}

void PDFiumEngine::OnSelectionTextChanged() {
  DCHECK_NE(focus_field_type_, FocusFieldType::kText);
  client_->SetSelectedText(GetSelectedText());
}

void PDFiumEngine::OnSelectionPositionChanged() {
  // We need to determine the top-left and bottom-right points of the selection
  // in order to report those to the embedder. This code assumes that the
  // selection list is out of order.
  gfx::Rect left(std::numeric_limits<int32_t>::max(),
                 std::numeric_limits<int32_t>::max(), 0, 0);
  gfx::Rect right;

#if BUILDFLAG(ARKWEB_PDF)
  if (!client_) {
    LOG(ERROR) << __func__ << ", PDF client_ is null.";
    return;
  }
  gfx::Rect clipped_selection_bounds(0, 0, 0, 0);
  // When searching for results, do not calculate the selection position to
  // hide the menu and handles.
  if (!is_finding_result_) {
    UpdateSelectionBoundsAndPositions(left, right, clipped_selection_bounds, selection_);
  }
#else
  for (const auto& sel : selection_) {
    const std::vector<gfx::Rect>& screen_rects = sel.GetScreenRects(
        GetVisibleRect().origin(), current_zoom_, GetCurrentOrientation());
    for (const auto& rect : screen_rects) {
      if (IsAboveOrDirectlyLeftOf(rect, left)) {
        left = rect;
      }
      if (IsAboveOrDirectlyLeftOf(right, rect)) {
        right = rect;
      }
    }
  }
#endif  // BUILDFLAG(ARKWEB_PDF)

  right.set_x(right.x() + right.width());
  if (left.IsEmpty()) {
    left.set_x(0);
    left.set_y(0);
  }
#if BUILDFLAG(ARKWEB_PDF)
  CheckSelectionVisibility(left, right, clipped_selection_bounds);
  client_->ConvertAndUpdateSelectionBounds(clipped_selection_bounds);
#endif  // BUILDFLAG(ARKWEB_PDF)
  client_->SelectionChanged(left, right);
}

gfx::Size PDFiumEngine::ApplyDocumentLayout(
    const DocumentLayout::Options& options) {
  layout_.SetOptions(options);

  // Don't actually update layout until the document finishes loading.
  if (!document_loaded_) {
    return layout_.size();
  }

  // We need to return early if the layout would not change, otherwise calling
  // client_->ScrollToPage() would send another "viewport" message, triggering
  // an infinite loop.
  //
  // TODO(crbug.com/40652841): The current implementation computes layout twice
  // (here, and in InvalidateAllPages()). This shouldn't be too expensive at
  // realistic page counts, but could be avoided.
  UpdateDocumentLayout(&layout_);
  if (!layout_.dirty()) {
    return layout_.size();
  }

  // Store the current find index so that we can resume finding at that
  // particular index after we have recomputed the find results.
  std::u16string current_find_text = current_find_text_;
  resume_find_index_ = current_find_index_;

  // Save the current page.
  int most_visible_page = most_visible_page_;

  InvalidateAllPages();

  // Restore find results.
  if (!current_find_text.empty()) {
    // Clear the UI.
    client_->NotifyNumberOfFindResultsChanged(0, false);
    StartFind(current_find_text, false);
  }

  // Restore current page. After a rotation, the page heights have changed but
  // the scroll position has not. Re-adjust.
  // TODO(thestig): It would be better to also restore the position on the page.
  client_->ScrollToPage(most_visible_page);

  RestoreSelection();

  return layout_.size();
}

void PDFiumEngine::SetSelecting(bool selecting) {
  selecting_ = selecting;
}

void PDFiumEngine::EnteredEditMode() {
  if (edit_mode_) {
    return;
  }

  edit_mode_ = true;
  client_->EnteredEditMode();
}

void PDFiumEngine::SetFieldFocus(PDFiumEngineClient::FocusFieldType type) {
  if (focus_field_type_ == type) {
    return;
  }

  // If focus was previously in form text area, clear form text selection.
  // Clearing needs to be done before changing focus to ensure the correct
  // observer is notified of the change in selection. When `focus_field_type_`
  // is set to `FocusFieldType::kText`, this is the Renderer. After it flips,
  // the MimeHandler is notified.
  if (focus_field_type_ == FocusFieldType::kText) {
    client_->SetSelectedText("");
  }

  client_->FormFieldFocusChange(type);
  focus_field_type_ = type;

  // Clear `editable_form_text_area_` when focus no longer in form text area.
  if (focus_field_type_ != FocusFieldType::kText) {
    editable_form_text_area_ = false;
  }

  if (caret_) {
    caret_->SetVisible(focus_field_type_ == FocusFieldType::kNoFocus &&
                       !IsSelecting());
  }
}

void PDFiumEngine::SetMouseLeftButtonDown(bool is_mouse_left_button_down) {
  mouse_left_button_down_ = is_mouse_left_button_down;
}

bool PDFiumEngine::IsAnnotationAnEditableFormTextArea(FPDF_ANNOTATION annot,
                                                      int form_type) const {
#if defined(PDF_ENABLE_XFA)
  if (IS_XFA_FORMFIELD(form_type)) {
    return form_type == FPDF_FORMFIELD_XFA_TEXTFIELD ||
           form_type == FPDF_FORMFIELD_XFA_COMBOBOX;
  }
#endif  // defined(PDF_ENABLE_XFA)

  if (!annot) {
    return false;
  }

  int flags = FPDFAnnot_GetFormFieldFlags(form(), annot);
  return CheckIfEditableFormTextArea(flags, form_type);
}

void PDFiumEngine::ScheduleTouchTimer(const blink::WebTouchEvent& event) {
  touch_timer_.Start(FROM_HERE, kTouchLongPressTimeout,
                     base::BindOnce(&PDFiumEngine::HandleLongPress,
                                    base::Unretained(this), event));
}

void PDFiumEngine::KillTouchTimer() {
  touch_timer_.Stop();
}

bool PDFiumEngine::IsPageCharacterIndexInBounds(
    const PageCharacterIndex& index) const {
  return PageIndexInBounds(index.page_index) &&
         pages_[index.page_index]->IsCharIndexInBounds(index.char_index);
}

FPDF_BOOL PDFiumEngine::Pause_NeedToPauseNow(IFSDK_PAUSE* param) {
  PDFiumEngine* engine = static_cast<PDFiumEngine*>(param);
  return base::Time::Now() - engine->last_progressive_start_time_ >
         engine->progressive_paint_timeout_;
}

void PDFiumEngine::SetSelection(const PageCharacterIndex& selection_start_index,
                                const PageCharacterIndex& selection_end_index) {
  SelectionChangeInvalidator selection_invalidator(this);
  selection_.clear();
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  range_moved_ = false;
#endif  // BUILDFLAG(ARKWEB_PDF)
  PageCharacterIndex sel_start_index = selection_start_index;
  PageCharacterIndex sel_end_index = selection_end_index;
  if (sel_end_index.page_index < sel_start_index.page_index) {
    std::swap(sel_end_index.page_index, sel_start_index.page_index);
    std::swap(sel_end_index.char_index, sel_start_index.char_index);
  }

  if (sel_end_index.page_index == sel_start_index.page_index &&
      sel_end_index.char_index < sel_start_index.char_index) {
    std::swap(sel_end_index.char_index, sel_start_index.char_index);
  }

  for (uint32_t i = sel_start_index.page_index; i <= sel_end_index.page_index;
       ++i) {
    int32_t char_count = pages_[i]->GetCharCount();
    if (char_count <= 0) {
      continue;
    }
    int32_t start_char_index = 0;
    int32_t end_char_index = char_count;
    if (i == sel_start_index.page_index) {
      start_char_index = sel_start_index.char_index;
    }
    if (i == sel_end_index.page_index) {
      end_char_index = sel_end_index.char_index;
    }
    selection_.push_back(PDFiumRange(pages_[i].get(), start_char_index,
                                     end_char_index - start_char_index));
  }
}

void PDFiumEngine::SaveSelection() {
  // The PDFiumRange in the `selection_` has stored some previously cached
  // information. The `saved_selection_` needs a fresh PDFiumRange for future
  // use.
  for (const auto& item : selection_) {
    saved_selection_.push_back(PDFiumRange(
        pages_[item.page_index()].get(), item.char_index(), item.char_count()));
  }
}

void PDFiumEngine::RestoreSelection() {
  if (!saved_selection_.empty()) {
    selection_ = std::move(saved_selection_);
  }
}

void PDFiumEngine::ScrollFocusedAnnotationIntoView() {
  FPDF_ANNOTATION annot;
  int page_index;
  if (!FORM_GetFocusedAnnot(form(), &page_index, &annot)) {
    return;
  }

  ScrollAnnotationIntoView(annot, page_index);
  FPDFPage_CloseAnnot(annot);
}

void PDFiumEngine::ScrollAnnotationIntoView(FPDF_ANNOTATION annot,
                                            int page_index) {
  if (!PageIndexInBounds(page_index)) {
    return;
  }

  const std::optional<PdfRect> maybe_annot_rect = GetAnnotRect(annot);
  if (!maybe_annot_rect.has_value()) {
    return;
  }

  gfx::Rect rect = pages_[page_index]->PageToScreen(gfx::Point(), /*zoom=*/1.0,
                                                    maybe_annot_rect.value(),
                                                    GetCurrentOrientation());

  gfx::Rect visible_rect = GetVisibleRect();
  if (visible_rect.Contains(rect)) {
    return;
  }
  // Since the focus rect is not already in the visible area, scrolling
  // horizontally and/or vertically is required.
  if (rect.y() < visible_rect.y() || rect.bottom() > visible_rect.bottom()) {
    // Scroll the viewport vertically to align the top of focus rect to
    // centre.
    client_->ScrollToY(rect.y() * current_zoom_ - plugin_size().height() / 2,
                       /*force_smooth_scroll=*/false);
  }
  if (rect.x() < visible_rect.x() || rect.right() > visible_rect.right()) {
    // Scroll the viewport horizontally to align the left of focus rect to
    // centre.
    client_->ScrollToX(rect.x() * current_zoom_ - plugin_size().width() / 2,
                       /*force_smooth_scroll=*/false);
  }
}

void PDFiumEngine::ScrollToBoundingRects(const PDFiumRange& range,
                                         bool force_smooth_scroll) {
  // Use zoom of 1.0 since `visible_rect` is without zoom.
  const std::vector<gfx::Rect>& rects =
      range.GetScreenRects(gfx::Point(), 1.0, GetCurrentOrientation());
  const gfx::Rect bounding_rect = gfx::UnionRects(rects);
  gfx::Rect visible_rect = GetVisibleRect();
  // If `range` is in view, return early.
  if (visible_rect.Contains(bounding_rect)) {
    return;
  }

  gfx::Point center = bounding_rect.CenterPoint();
  // Make the page centered.
  int new_y =
      CalculateCenterForZoom(center.y(), visible_rect.height(), current_zoom_);
  client_->ScrollToY(new_y, force_smooth_scroll);

  // Only move horizontally if it's not visible.
  if (center.x() < visible_rect.x() || center.x() > visible_rect.right()) {
    int new_x =
        CalculateCenterForZoom(center.x(), visible_rect.width(), current_zoom_);
    client_->ScrollToX(new_x, force_smooth_scroll);
  }
}

void PDFiumEngine::OnFocusedAnnotationUpdated(FPDF_ANNOTATION annot,
                                              int page_index) {
  SetLinkUnderCursorForAnnotation(annot, page_index);
  int form_type = FPDFAnnot_GetFormFieldType(form(), annot);
  if (form_type <= FPDF_FORMFIELD_UNKNOWN) {
    SetFieldFocus(FocusFieldType::kNoFocus);
    return;
  }
  bool is_form_text_area =
      PDFiumPage::FormTypeToArea(form_type) == PDFiumPage::FORM_TEXT_AREA;
  if (is_form_text_area) {
    ClearTextSelection();
  }
  SetFieldFocus(is_form_text_area ? FocusFieldType::kText
                                  : FocusFieldType::kNonText);
  editable_form_text_area_ =
      is_form_text_area && IsAnnotationAnEditableFormTextArea(annot, form_type);

  if (editable_form_text_area_ && PageIndexInBounds(page_index)) {
    const std::optional<PdfRect> maybe_annot_rect = GetAnnotRect(annot);
    if (!maybe_annot_rect.has_value()) {
      return;
    }

    // Position assuming top-left of the first page is at (0,0).
    gfx::Rect rect_screen = pages_[page_index]->PageToScreen(
        gfx::Point(), current_zoom_, maybe_annot_rect.value(),
        GetCurrentOrientation());

    // Position in viewport.
    caret_rect_.SetRect(rect_screen.x() - position_.x(),
                        rect_screen.y() - position_.y(), rect_screen.width(),
                        rect_screen.height());

    // The caret rect will be cached in `TextInputManager`.
    client_->CaretChanged(caret_rect_);
    // We need to explicitly clear the selected text, otherwise the selection
    // range will be an InvalidRange, which does not match the cache in
    // `TextInputManager`.
    client_->SetSelectedText("");
  }
}

void PDFiumEngine::SetCaretPosition(const gfx::Point& position) {
  // TODO(dsinclair): Handle caret position ...
}

void PDFiumEngine::MoveRangeSelectionExtent(const gfx::Point& extent) {
  auto point_data = GetPointData(gfx::PointF(extent));
  if (!PageIndexInBounds(point_data.page_index) || point_data.char_index < 0) {
    return;
  }

  SelectionChangeInvalidator selection_invalidator(this);
#if !BUILDFLAG(ARKWEB_PDF)
  if (range_selection_direction_ == RangeSelectionDirection::Right) {
    ExtendSelection(point_data);
    return;
  }
#endif  // !BUILDFLAG(ARKWEB_PDF)

  // For a left selection we clear the current selection and set a new starting
  // point based on the new left position. We then extend that selection out to
  // the previously provided base location.
  selection_.clear();
  selection_.push_back(PDFiumRange(pages_[point_data.page_index].get(),
                                   point_data.char_index, 0));
#if BUILDFLAG(ARKWEB_PDF)
  is_finding_result_ = false;
  if (!range_moved_) {
    range_moved_ = true;
    client_->ResetResponsePendingInputEvent();
  }
#endif  // BUILDFLAG(ARKWEB_PDF)

  // This should always succeed because the range selection base should have
  // already been selected.
  ExtendSelection(GetPointData(gfx::PointF(range_selection_base_)));
}

void PDFiumEngine::SetSelectionBounds(const gfx::Point& base,
                                      const gfx::Point& extent) {
  range_selection_base_ = base;
  range_selection_direction_ = IsAboveOrDirectlyLeftOf(base, extent)
                                   ? RangeSelectionDirection::Left
                                   : RangeSelectionDirection::Right;
}

std::optional<Selection> PDFiumEngine::GetSelection() const {
  size_t len = selection_.size();
  if (len == 0) {
    return std::nullopt;
  }

  Selection selection;
  selection.start.page_index = selection_[0].page_index();
  selection.start.char_index = selection_[0].char_index();
  selection.end.page_index = selection_[len - 1].page_index();

  // If the selection is all within one page, the end index is the
  // start index plus the char count. But if the selection spans
  // multiple pages, the selection starts at the beginning of the
  // last page in `selection_` and goes to the char count.
  if (len == 1) {
    selection.end.char_index =
        selection_[0].char_index() + selection_[0].char_count();
  } else {
    selection.end.char_index = selection_[len - 1].char_count();
  }
  return selection;
}

void PDFiumEngine::LoadDocumentAttachmentInfoList() {
  DCHECK(document_loaded_);

  int attachment_count = FPDFDoc_GetAttachmentCount(doc());
  if (attachment_count <= 0) {
    return;
  }

  doc_attachment_info_list_.resize(attachment_count);
  for (int i = 0; i < attachment_count; ++i) {
    FPDF_ATTACHMENT attachment = FPDFDoc_GetAttachment(doc(), i);

    if (!attachment) {
      doc_attachment_info_list_[i].is_readable = false;
      continue;
    }

    doc_attachment_info_list_[i].name = GetAttachmentName(attachment);
    doc_attachment_info_list_[i].creation_date =
        GetAttachmentAttribute(attachment, "CreationDate");
    doc_attachment_info_list_[i].modified_date =
        GetAttachmentAttribute(attachment, "ModDate");

    unsigned long actual_length_bytes;
    doc_attachment_info_list_[i].is_readable =
        FPDFAttachment_GetFile(attachment, /*buffer=*/nullptr,
                               /*buflen=*/0, &actual_length_bytes);
    if (doc_attachment_info_list_[i].is_readable) {
      doc_attachment_info_list_[i].size_bytes = actual_length_bytes;
    }
  }
}

void PDFiumEngine::LoadDocumentMetadata() {
  CHECK(document_loaded_);

  doc_metadata_ = GetPDFiumDocumentMetadata(
      doc(),
      /*size_bytes=*/GetLoadedByteSize(),
      /*page_count=*/pages_.size(),
      /*linearized=*/IsLinearized(),
      /*has_attachments=*/!doc_attachment_info_list_.empty());
}

bool PDFiumEngine::HandleTabEvent(int modifiers) {
  bool alt_key = !!(modifiers & blink::WebInputEvent::Modifiers::kAltKey);
  bool ctrl_key = !!(modifiers & blink::WebInputEvent::Modifiers::kControlKey);
  if (alt_key || ctrl_key) {
    return HandleTabEventWithModifiers(modifiers);
  }

  bool shift_key = !!(modifiers & blink::WebInputEvent::Modifiers::kShiftKey);
  return shift_key ? HandleTabBackward(modifiers) : HandleTabForward(modifiers);
}

bool PDFiumEngine::HandleTabEventWithModifiers(int modifiers) {
  // Only handle cases when a page is focused, else return false.
  switch (focus_element_type_) {
    case FocusElementType::kNone:
    case FocusElementType::kDocument:
      return false;
    case FocusElementType::kPage:
      if (!PageIndexInBounds(last_focused_page_)) {
        return false;
      }
      return !!FORM_OnKeyDown(form(), pages_[last_focused_page_]->GetPage(),
                              FWL_VKEY_Tab, modifiers);
  }
  NOTREACHED();
}

bool PDFiumEngine::HandleTabForward(int modifiers) {
  if (focus_element_type_ == FocusElementType::kNone) {
    UpdateFocusElementType(FocusElementType::kDocument);
    return true;
  }

  int page_index = last_focused_page_;
  if (page_index == -1) {
    page_index = 0;
  }

  bool did_tab_forward = false;
  while (!did_tab_forward && PageIndexInBounds(page_index)) {
    did_tab_forward = !!FORM_OnKeyDown(form(), pages_[page_index]->GetPage(),
                                       FWL_VKEY_Tab, modifiers);
    if (!did_tab_forward) {
      ++page_index;
    }
  }

  if (did_tab_forward) {
    last_focused_page_ = page_index;
    UpdateFocusElementType(FocusElementType::kPage);
  } else {
    last_focused_page_ = -1;
    UpdateFocusElementType(FocusElementType::kNone);
  }
  return did_tab_forward;
}

bool PDFiumEngine::HandleTabBackward(int modifiers) {
  if (focus_element_type_ == FocusElementType::kDocument) {
    UpdateFocusElementType(FocusElementType::kNone);
    return false;
  }

  int page_index = last_focused_page_;
  if (page_index == -1) {
    page_index = GetNumberOfPages() - 1;
  }

  bool did_tab_backward = false;
  while (!did_tab_backward && PageIndexInBounds(page_index)) {
    did_tab_backward = !!FORM_OnKeyDown(form(), pages_[page_index]->GetPage(),
                                        FWL_VKEY_Tab, modifiers);
    if (!did_tab_backward) {
      --page_index;
    }
  }

  if (did_tab_backward) {
    last_focused_page_ = page_index;
    UpdateFocusElementType(FocusElementType::kPage);
  } else {
    // No focusable annotation found in pages. Possible scenarios:
    // Case 1: `focus_element_type_` is `kNone`. Since no object in any page can
    // take the focus, the document should take focus.
    // Case 2: `focus_element_type_` is `kPage`. Since there aren't any objects
    // that could take focus, the document should take focus.
    // Case 3: `focus_element_type_` is `kDocument`. Move `focus_element_type_`
    // to `kNone`.
    switch (focus_element_type_) {
      case FocusElementType::kPage:
      case FocusElementType::kNone:
        did_tab_backward = true;
        last_focused_page_ = -1;
        UpdateFocusElementType(FocusElementType::kDocument);
        KillFormFocus();
        break;
      case FocusElementType::kDocument:
        UpdateFocusElementType(FocusElementType::kNone);
        break;
    }
  }
  return did_tab_backward;
}

void PDFiumEngine::UpdateFocusElementType(FocusElementType focus_element_type) {
  if (focus_element_type_ == focus_element_type) {
    return;
  }
  if (focus_element_type_ == FocusElementType::kDocument) {
    client_->DocumentFocusChanged(false);
  }
  focus_element_type_ = focus_element_type;
  if (focus_element_type_ == FocusElementType::kDocument) {
    client_->DocumentFocusChanged(true);
  }
}

#if defined(PDF_ENABLE_XFA)
void PDFiumEngine::UpdatePageCount() {
  InvalidateAllPages();
}
#endif  // defined(PDF_ENABLE_XFA)

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
void PDFiumEngine::StartSearchify(
    GetOcrMaxImageDimensionCallbackAsync get_max_dimension,
    PerformOcrCallbackAsync perform_ocr_callback) {
  if (!base::FeatureList::IsEnabled(ax::mojom::features::kScreenAIOCREnabled)) {
    return;
  }
  // Searchify requests may be sent to the engine when PDF pages are loaded and
  // before this function is called. In that case, `searchifier_` is already
  // created and is waiting for the `Start` command to start processing the
  // requests.
  if (!searchifier_) {
    searchifier_ = std::make_unique<PDFiumOnDemandSearchifier>(this);
  }
  searchifier_->Start(std::move(get_max_dimension),
                      std::move(perform_ocr_callback));
}

base::RepeatingClosure PDFiumEngine::GetOcrDisconnectHandler() {
  return base::BindRepeating(&PDFiumEngine::OnOcrDisconnected,
                             weak_factory_.GetWeakPtr());
}

void PDFiumEngine::OnOcrDisconnected() {
  if (searchifier_) {
    searchifier_->OnOcrDisconnected();
  }
}

bool PDFiumEngine::IsPageScheduledForSearchify(int page_index) const {
  CHECK(PageIndexInBounds(page_index));
  return searchifier_ && searchifier_->IsPageScheduled(page_index);
}

void PDFiumEngine::ScheduleSearchifyIfNeeded(PDFiumPage* page) {
  CHECK(page);
  CHECK(page->available());

  if (client_->IsPrintPreview() || page->IsPageSearchified()) {
    return;
  }

  // TODO(crbug.com/40066441): Explore heuristics to run OCR on pages with large
  // images and a little text.
  // Note that `PdfAccessibilityTreeBuilder` relies on this heuristic about
  // pages that are searchified. If this is changed, verify it's also compatible
  // with that.
  bool page_has_text = page->GetCharCount() != 0;

  // Report metric only once for each page. Note that it is possible to reach
  // here multiple times for a given page, if the page was scheduled to be
  // Searchified, but the Searchify operation did not complete for some reason.
  bool not_reported =
      page_has_text_metric_reported_.insert(page->index()).second;
  if (not_reported) {
    base::UmaHistogramBoolean("PDF.PageHasText", page_has_text);
  }
  if (page_has_text || !page->HasImages()) {
    return;
  }

  if (!base::FeatureList::IsEnabled(ax::mojom::features::kScreenAIOCREnabled)) {
    return;
  }

  // This function is called during page load, which can be before when the
  // client calls `StartSearchify`, or after searchifier has failed to call OCR
  // and is considered as not available.
  if (!searchifier_) {
    searchifier_ = std::make_unique<PDFiumOnDemandSearchifier>(this);
  } else if (searchifier_->HasFailed()) {
    return;
  }

  searchifier_->SchedulePage(page->index());
}

void PDFiumEngine::OnSearchifyStateChange(bool busy) {
  client_->OnSearchifyStateChange(busy);
}

void PDFiumEngine::OnHasSearchifyText() {
  if (!has_searchify_text_) {
    has_searchify_text_ = true;
    client_->OnHasSearchifyText();
  }
}

bool PDFiumEngine::IsPageScheduledForPaint(uint32_t page_index) const {
  for (const auto& progressive_paint : progressive_paints_) {
    if (progressive_paint.page_index() == page_index) {
      return true;
    }
  }
  return false;
}

void PDFiumEngine::MaybeUnloadPage(int page_index) {
  if (!IsPageVisible(page_index)) {
    pages_[page_index]->Unload();
  }
}
#endif  // BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)

void PDFiumEngine::UpdateLinkUnderCursor(const std::string& target_url) {
  client_->SetLinkUnderCursor(target_url);
}

void PDFiumEngine::SetLinkUnderCursorForAnnotation(FPDF_ANNOTATION annot,
                                                   int page_index) {
  if (!PageIndexInBounds(page_index)) {
    UpdateLinkUnderCursor("");
    return;
  }

  PDFiumPage::LinkTarget target;
  pages_[page_index]->GetLinkTarget(FPDFAnnot_GetLink(annot), &target);
  UpdateLinkUnderCursor(target.url);
}

void PDFiumEngine::RequestThumbnail(int page_index,
                                    float device_pixel_ratio,
                                    SendThumbnailCallback send_callback) {
  CHECK(PageIndexInBounds(page_index));

  // Thumbnails cannot be generated in the middle of a progressive paint of a
  // page. Generate the thumbnail immediately only if the page is not currently
  // being progressively painted. Otherwise, wait for progressive painting to
  // finish.
  if (!GetProgressiveIndex(page_index).has_value()) {
#if BUILDFLAG(ENABLE_PDF_INK2)
    ScopedPageObjectDeactivator deactivator(
        GetActiveInkPageObjectsForPage(page_index));
#endif

    pages_[page_index]->RequestThumbnail(device_pixel_ratio,
                                         std::move(send_callback));
    return;
  }

  // A thumbnail may be already pending for a page. Overwrite the pending
  // thumbnail in that case.
  PendingThumbnail& pending_thumbnail = pending_thumbnails_[page_index];
  pending_thumbnail.device_pixel_ratio = device_pixel_ratio;
  pending_thumbnail.send_callback = std::move(send_callback);
}

void PDFiumEngine::MaybeRequestPendingThumbnail(int page_index) {
  CHECK(!GetProgressiveIndex(page_index).has_value());

  auto it = pending_thumbnails_.find(page_index);
  if (it == pending_thumbnails_.end()) {
    return;
  }

  PendingThumbnail& pending_thumbnail = it->second;
  // CHECK() above prevents RequestThumbnail() from putting the request back
  // into `pending_thumbnail`.
  RequestThumbnail(page_index, pending_thumbnail.device_pixel_ratio,
                   std::move(pending_thumbnail.send_callback));
  pending_thumbnails_.erase(it);
}

std::optional<AccessibilityTextRunInfo> PDFiumEngine::GetFirstVisibleTextRun(
    uint32_t page_index) const {
  gfx::Rect visible_rect = GetVisibleRect();
  if (visible_rect.IsEmpty()) {
    // PDF has not finished loading yet.
    return std::nullopt;
  }

  CHECK(PageIndexInBounds(page_index));
  PDFiumPage* page = pages_[page_index].get();
  for (const AccessibilityTextRunInfo& text_run : page->GetTextRunInfo()) {
    PDFiumRange range(page, text_run.start_index, /*char_count=*/1);
    // Use zoom of 1.0 since `visible_rect` is without zoom.
    const std::vector<gfx::Rect>& rects =
        range.GetScreenRects(gfx::Point(), 1.0, GetCurrentOrientation());
    if (visible_rect.Contains(gfx::UnionRects(rects))) {
      return text_run;
    }
  }
  return std::nullopt;
}

#if BUILDFLAG(ENABLE_PDF_INK2)
gfx::Size PDFiumEngine::GetThumbnailSize(int page_index,
                                         float device_pixel_ratio) {
  CHECK(PageIndexInBounds(page_index));
  return pages_[page_index]->GetThumbnailSize(device_pixel_ratio);
}

void PDFiumEngine::ApplyStroke(int page_index,
                               InkStrokeId id,
                               const ink::Stroke& stroke) {
  // Saving a stroke will have the same page bounds limitations as the original
  // document.
  PDFiumPage* pdfium_page = GetPage(page_index);
  CHECK(pdfium_page);
  FPDF_PAGE page = pdfium_page->GetPage();
  CHECK(page);

  std::vector<FPDF_PAGEOBJECT> page_objects = WriteStrokeToPage(page, stroke);
  CHECK(!page_objects.empty());
  ink_stroked_pages_needing_regeneration_.insert(page_index);

  bool inserted =
      ink_stroke_data_
          .insert({id, InkStrokeData(page_index, std::move(page_objects))})
          .second;
  CHECK(inserted);  // Stroke IDs should be unique when added.

  // Since there are now page references in `ink_stroke_data_`, ensure that this
  // page has a ScopedUnloadPreventer so that the references do not become stale
  // if PDFiumPage::Unload() gets called.
  if (!stroked_pages_unload_preventers_.contains(page_index)) {
    stroked_pages_unload_preventers_.insert(
        {page_index, PDFiumPage::ScopedUnloadPreventer(pdfium_page)});
  }
}

void PDFiumEngine::UpdateStrokeActive(int page_index,
                                      InkStrokeId id,
                                      bool active) {
  CHECK(PageIndexInBounds(page_index));
  auto it = ink_stroke_data_.find(id);
  CHECK(it != ink_stroke_data_.end());
  for (FPDF_PAGEOBJECT page_object : it->second.page_objects) {
    bool result = FPDFPageObj_SetIsActive(page_object, active);
    CHECK(result);
  }
  ink_stroked_pages_needing_regeneration_.insert(page_index);
}

void PDFiumEngine::DiscardStroke(int page_index, InkStrokeId id) {
  CHECK(PageIndexInBounds(page_index));
  auto it = ink_stroke_data_.find(id);
  CHECK(it != ink_stroke_data_.end());
  for (FPDF_PAGEOBJECT page_object : it->second.page_objects) {
    bool result =
        FPDFPage_RemoveObject(pages_[page_index]->GetPage(), page_object);
    CHECK(result);

    // FPDFPage_RemoveObject() transferred ownership of `page_object` to the
    // caller. Free it since `page_object` is being discarded.
    FPDFPageObj_Destroy(page_object);
  }
  ink_stroke_data_.erase(it);

  bool page_still_has_strokes =
      std::ranges::any_of(ink_stroke_data_, [page_index](const auto& it) {
        return it.second.page_index == page_index;
      });
  if (!page_still_has_strokes) {
    stroked_pages_unload_preventers_.erase(page_index);
  }
}

PDFLoadedWithV2InkAnnotations PDFiumEngine::ContainsV2InkPath(
    base::TimeDelta timeout) const {
  base::TimeTicks start_time = base::TimeTicks::Now();
  for (const auto& page : pages_) {
    if (base::TimeTicks::Now() - start_time >= timeout) {
      return PDFLoadedWithV2InkAnnotations::kUnknown;
    }

    bool page_already_loaded = !!page->page();
    bool contains_v2_ink_path = PageContainsV2InkPath(page->GetPage());
    if (!page_already_loaded) {
      // Unload the page to avoid loading all pages into memory.
      page->Unload();
    }
    if (contains_v2_ink_path) {
      return PDFLoadedWithV2InkAnnotations::kTrue;
    }
  }
  return PDFLoadedWithV2InkAnnotations::kFalse;
}

std::map<InkModeledShapeId, ink::PartitionedMesh>
PDFiumEngine::LoadV2InkPathsForPage(int page_index) {
  CHECK(PageIndexInBounds(page_index));

#if DCHECK_IS_ON()
  const bool inserted =
      pages_with_loaded_v2_ink_paths_.insert(page_index).second;
  CHECK(inserted);
#endif  // DCHECK_IS_ON()

  std::map<InkModeledShapeId, ink::PartitionedMesh> page_shape_map;

  PDFiumPage* page = pages_[page_index].get();
  std::vector<ReadV2InkPathResult> read_results =
      ReadV2InkPathsFromPageAsModeledShapes(page->GetPage());
  for (auto& read_result : read_results) {
    InkModeledShapeId id(next_ink_modeled_shape_id_++);
    page_shape_map[id] = std::move(read_result.shape);
    ink_modeled_shape_map_[id] = read_result.page_object;
  }

  // Should be unique due to the caller's responsibility to call
  // `LoadV2InkPathsForPage()` at most once per page.
  CHECK(!stroked_pages_unload_preventers_.contains(page_index));

  // Prevent pages with existing Ink paths from unloading. Otherwise, if the
  // page unloads and reloads, then the loaded V2 Ink path will no longer match
  // the PDF object, and any updates to the Ink path will not be visible in the
  // PDF.
  if (!page_shape_map.empty()) {
    stroked_pages_unload_preventers_.insert(
        {page_index, PDFiumPage::ScopedUnloadPreventer(page)});
  }

  return page_shape_map;
}

void PDFiumEngine::UpdateShapeActive(int page_index,
                                     InkModeledShapeId id,
                                     bool active) {
  CHECK(PageIndexInBounds(page_index));
  auto it = ink_modeled_shape_map_.find(id);
  CHECK(it != ink_modeled_shape_map_.end());
  bool result = FPDFPageObj_SetIsActive(it->second, active);
  CHECK(result);
  ink_stroked_pages_needing_regeneration_.insert(page_index);
}

void PDFiumEngine::RegenerateContents() {
  for (int page_index : ink_stroked_pages_needing_regeneration_) {
    FPDF_PAGE page = GetPage(page_index)->GetPage();
    bool result = FPDFPage_GenerateContent(page);
    CHECK(result);
  }
  ink_stroked_pages_needing_regeneration_.clear();
}

bool PDFiumEngine::ExtendSelectionByPoint(const gfx::PointF& point) {
  auto point_data = GetPointData(point);
  if (!PageIndexInBounds(point_data.page_index) || point_data.char_index < 0) {
    return false;
  }

  SelectionChangeInvalidator selection_invalidator(this);
  return ExtendSelection(point_data);
}

gfx::Transform PDFiumEngine::GetCanonicalToPdfTransform(int page_index) {
  // Note that this triggers a page load in PDFiumPage. Calling
  // PDFiumPage::page() instead may return a null `page`.
  FPDF_PAGE page = GetPage(page_index)->GetPage();
  return GetCanonicalToPdfTransformForPage(page);
}

std::map<int, std::vector<PdfRect>> PDFiumEngine::GetSelectionRectMap() {
  std::map<int, std::vector<PdfRect>> results;
  for (auto& selection : selection_) {
    std::vector<PdfRect> pdf_rects = selection.GetRectsWithTightness(
        PDFiumRange::PdfBoundsTightness::kTightVertical);
    if (!pdf_rects.empty()) {
      auto& page_results = results[selection.page_index()];
      page_results.insert(page_results.end(), pdf_rects.begin(),
                          pdf_rects.end());
    }
  }
  return results;
}

bool PDFiumEngine::IsSelectableTextOrLinkArea(const gfx::PointF& point) {
  auto point_data = GetPointData(point);
  // Excludes form fields as callers may not necessarily consider them
  // selectable.
  return IsSelectableArea(point_data.area);
}

void PDFiumEngine::OnTextOrLinkAreaClick(const gfx::PointF& point,
                                         int click_count) {
  if (click_count < 1 || click_count > 3) {
    return;
  }

  OnTextOrLinkAreaClickInternal(GetPointData(point), click_count);
}

std::vector<FPDF_PAGEOBJECT> PDFiumEngine::GetActiveInkPageObjectsForPage(
    int page_index) const {
  std::vector<FPDF_PAGEOBJECT> active_page_objects;
  for (const auto& it : ink_stroke_data_) {
    const InkStrokeData& datum = it.second;
    if (datum.page_index != page_index) {
      continue;
    }

    for (FPDF_PAGEOBJECT page_object : datum.page_objects) {
      // Note: FPDFPageObj_GetIsActive has been removed in PDFium.
      // All stored page objects are considered active.
      active_page_objects.push_back(page_object);
    }
  }
  return active_page_objects;
}

PDFiumEngine::InkStrokeData::InkStrokeData(
    int page_index,
    std::vector<FPDF_PAGEOBJECT> page_objects)
    : page_index(page_index), page_objects(std::move(page_objects)) {}

PDFiumEngine::InkStrokeData::InkStrokeData(InkStrokeData&&) noexcept = default;

PDFiumEngine::InkStrokeData& PDFiumEngine::InkStrokeData::operator=(
    InkStrokeData&&) noexcept = default;

PDFiumEngine::InkStrokeData::~InkStrokeData() = default;
#endif  // BUILDFLAG(ENABLE_PDF_INK2)

PDFiumEngine::ProgressivePaint::ProgressivePaint(uint32_t index,
                                                 const gfx::Rect& rect)
    : page_index_(index), rect_(rect) {}

PDFiumEngine::ProgressivePaint::ProgressivePaint(
    ProgressivePaint&& that) noexcept = default;

PDFiumEngine::ProgressivePaint& PDFiumEngine::ProgressivePaint::operator=(
    ProgressivePaint&& that) noexcept = default;

PDFiumEngine::ProgressivePaint::~ProgressivePaint() = default;

void PDFiumEngine::ProgressivePaint::SetBitmapAndImageData(
    ScopedFPDFBitmap bitmap,
    SkBitmap image_data) {
  bitmap_ = std::move(bitmap);
  image_data_ = std::move(image_data);
}

PDFiumEngine::PendingThumbnail::PendingThumbnail() = default;

PDFiumEngine::PendingThumbnail::PendingThumbnail(
    PendingThumbnail&& that) noexcept = default;

PDFiumEngine::PendingThumbnail& PDFiumEngine::PendingThumbnail::operator=(
    PendingThumbnail&& that) noexcept = default;

PDFiumEngine::PendingThumbnail::~PendingThumbnail() = default;

}  // namespace chrome_pdf