// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/ui/task_manager/task_manager_table_model.h"

#include <stddef.h>

#include <algorithm>
#include <string>
#include <string_view>
#include <vector>

#include "base/byte_count.h"
#include "base/command_line.h"
#include "base/i18n/message_formatter.h"
#include "base/i18n/number_formatting.h"
#include "base/i18n/rtl.h"
#include "base/i18n/string_search.h"
#include "base/i18n/time_formatting.h"
#include "base/i18n/unicodestring.h"
#include "base/memory/ptr_util.h"
#include "base/numerics/safe_conversions.h"
#include "base/process/process_handle.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/values.h"
#include "build/build_config.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/task_manager/common/task_manager_features.h"
#include "chrome/browser/task_manager/sampling/task_group.h"
#include "chrome/browser/task_manager/task_manager_interface.h"
#include "chrome/browser/task_manager/task_manager_metrics_recorder.h"
#include "chrome/browser/task_manager/task_manager_observer.h"
#include "chrome/browser/ui/task_manager/task_manager_columns.h"
#include "chrome/common/pref_names.h"
#include "chrome/grit/generated_resources.h"
#include "components/prefs/scoped_user_pref_update.h"
#include "content/public/common/result_codes.h"
#include "third_party/icu/source/common/unicode/utypes.h"
#include "third_party/icu/source/i18n/unicode/listformatter.h"
#include "ui/base/l10n/l10n_util.h"
#include "ui/base/models/image_model.h"
#include "ui/base/models/table_model_observer.h"
#include "ui/base/text/bytes_formatting.h"

namespace task_manager {

namespace {

#if BUILDFLAG(IS_MAC)
// Match Activity Monitor's default refresh rate.
constexpr base::TimeDelta kRefreshTime = base::Seconds(2);
#else
constexpr base::TimeDelta kRefreshTime = base::Seconds(1);
#endif  // BUILDFLAG(IS_MAC)

// The columns that are shared by a group will show the value of the column
// only once per group.
bool IsSharedByGroup(int column_id) {
  switch (column_id) {
    case IDS_TASK_MANAGER_MEM_FOOTPRINT_COLUMN:
    case IDS_TASK_MANAGER_SWAPPED_MEM_COLUMN:
    case IDS_TASK_MANAGER_CPU_COLUMN:
    case IDS_TASK_MANAGER_START_TIME_COLUMN:
    case IDS_TASK_MANAGER_CPU_TIME_COLUMN:
    case IDS_TASK_MANAGER_NET_COLUMN:
    case IDS_TASK_MANAGER_PROCESS_ID_COLUMN:
    case IDS_TASK_MANAGER_JAVASCRIPT_MEMORY_ALLOCATED_COLUMN:
    case IDS_TASK_MANAGER_VIDEO_MEMORY_COLUMN:
    case IDS_TASK_MANAGER_SQLITE_MEMORY_USED_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN:
    case IDS_TASK_MANAGER_IDLE_WAKEUPS_COLUMN:
    case IDS_TASK_MANAGER_HARD_FAULTS_COLUMN:
    case IDS_TASK_MANAGER_OPEN_FD_COUNT_COLUMN:
    case IDS_TASK_MANAGER_PROCESS_PRIORITY_COLUMN:
      return true;
    default:
      return false;
  }
}

// Used to sort various column values.
template <class T>
int ValueCompare(T value1, T value2) {
  if (value1 == value2) {
    return 0;
  }
  return value1 < value2 ? -1 : 1;
}

// This forces NaN values to the bottom of the table.
template <>
int ValueCompare(double value1, double value2) {
  if (std::isnan(value1)) {
    return std::isnan(value2) ? 0 : -1;
  }
  if (std::isnan(value2)) {
    return 1;
  }
  if (value1 == value2) {
    return 0;
  }
  return value1 < value2 ? -1 : 1;
}

// This is used to sort process priority. We want the backgrounded process (with
// a true value) to come first.
int BooleanCompare(bool value1, bool value2) {
  if (value1 == value2) {
    return 0;
  }

  return value1 ? -1 : 1;
}

// Used when one or both of the results to compare are unavailable.
int OrderUnavailableValue(bool v1, bool v2) {
  if (!v1 && !v2) {
    return 0;
  }
  return v1 ? 1 : -1;
}

bool ShouldKeepTaskForTabsAndExtensions(Task::Type type,
                                        Task::SubType subtype) {
  switch (type) {
    case Task::RENDERER:
      // Only keep renderers with no sub type. Any other explicitly labeled
      // renderers, such as Spare Renderers, or Unknown renderers should show up
      // in Browser/System.
      return subtype == Task::SubType::kNoSubType;
    case Task::EXTENSION:
    case Task::GUEST:
      return true;
    default:
      return false;
  }
}

bool ShouldKeepTaskForSystem(Task::Type type, Task::SubType subtype) {
  // These major types are categorized as "System" processes, because they
  // have some special interaction with Chromium internals.
  switch (type) {
    case Task::BROWSER:
    case Task::GPU:
    case Task::ARC:
    case Task::CROSTINI:
    case Task::ZYGOTE:
    case Task::UTILITY:
    case Task::SANDBOX_HELPER:
      return true;

    case Task::RENDERER:
      // The subtypes are normal renderers, however killing these is not
      // beneficial to the user, so they are categorized under Browser/System.
      return subtype != Task::SubType::kNoSubType;

    default:
      return false;
  }
}

}  // namespace

// A class to stringify the task manager's values into string16s and to
// cache the common strings that will be reused many times like "N/A" and so on.
class TaskManagerValuesStringifier {
 public:
  TaskManagerValuesStringifier()
      : n_a_string_(l10n_util::GetStringUTF16(IDS_TASK_MANAGER_NA_CELL_TEXT)),
        zero_string_(base::FormatNumber(0)),
        backgrounded_string_(
            l10n_util::GetStringUTF16(IDS_TASK_MANAGER_BACKGROUNDED_TEXT)),
        foregrounded_string_(
            l10n_util::GetStringUTF16(IDS_TASK_MANAGER_FOREGROUNDED_TEXT)),
        asterisk_string_(u"*") {}

  TaskManagerValuesStringifier(const TaskManagerValuesStringifier&) = delete;
  TaskManagerValuesStringifier& operator=(const TaskManagerValuesStringifier&) =
      delete;
  ~TaskManagerValuesStringifier() = default;

  std::u16string GetCpuUsageText(double cpu_usage) {
    if (std::isnan(cpu_usage)) {
      return n_a_string_;
    }
    return base::FormatDouble(cpu_usage, /*min_fractional_digits=*/1,
                              /*max_fractional_digits=*/1);
  }

  std::u16string GetStartTimeText(base::Time start_time) {
    if (start_time.is_null()) {
      return n_a_string_;
    }

    return base::TimeFormatShortDateAndTime(start_time);
  }

  std::u16string GetCpuTimeText(base::TimeDelta cpu_time) {
    if (cpu_time.is_zero()) {
      return n_a_string_;
    }

    std::u16string duration;
    return base::TimeDurationFormatWithSeconds(
               cpu_time, base::DURATION_WIDTH_NARROW, &duration)
               ? duration
               : n_a_string_;
  }

  std::u16string GetMemoryUsageText(base::ByteCount memory_usage,
                                    bool has_duplicates) {
    if (memory_usage.is_negative()) {
      return n_a_string_;
    }

#if BUILDFLAG(IS_MAC)
    // System expectation is to show "100 kB", "200 MB", etc.
    std::u16string memory_text = ui::FormatBytes(memory_usage);
#else
    std::u16string memory_text = base::FormatNumber(memory_usage.InKiB());
    // Adjust number string if necessary.
    base::i18n::AdjustStringForLocaleDirection(&memory_text);
    memory_text =
        l10n_util::GetStringFUTF16(IDS_TASK_MANAGER_MEM_CELL_TEXT, memory_text);
#endif  // BUILDFLAG(IS_MAC)

    if (has_duplicates) {
      memory_text += asterisk_string_;
    }

    return memory_text;
  }

  std::u16string GetIdleWakeupsText(int idle_wakeups) {
    if (idle_wakeups == -1) {
      return n_a_string_;
    }

    return base::FormatNumber(idle_wakeups);
  }

  std::u16string GetHardFaultsText(int hard_faults) {
    if (hard_faults == -1) {
      return n_a_string_;
    }

    return base::FormatNumber(hard_faults);
  }

  std::u16string GetWindowsHandlesText(int64_t current, int64_t peak) {
    return l10n_util::GetStringFUTF16(IDS_TASK_MANAGER_HANDLES_CELL_TEXT,
                                      base::FormatNumber(current),
                                      base::FormatNumber(peak));
  }

  std::u16string GetNetworkUsageText(base::ByteCount network_usage) {
    if (network_usage.is_negative()) {
      return n_a_string_;
    }

    if (network_usage.is_zero()) {
      return zero_string_;
    }

    std::u16string net_byte = ui::FormatSpeed(network_usage);
    // Force number string to have LTR directionality.
    return base::i18n::GetDisplayStringInLTRDirectionality(net_byte);
  }

  std::u16string GetProcessIdText(base::ProcessId proc_id) {
    // The PID is a "computer number" and so is deliberately not localized.
    return base::NumberToString16(proc_id);
  }

  std::u16string FormatAllocatedAndUsedMemory(base::ByteCount allocated,
                                              base::ByteCount used) {
    return l10n_util::GetStringFUTF16(
        IDS_TASK_MANAGER_CACHE_SIZE_CELL_TEXT,
        ui::FormatBytesWithUnits(allocated, ui::DataUnits::kKibibyte, false),
        ui::FormatBytesWithUnits(used, ui::DataUnits::kKibibyte, false));
  }

  std::u16string GetWebCacheStatText(
      const blink::WebCacheResourceTypeStat& stat) {
    return GetMemoryUsageText(base::ByteCount(stat.size), false);
  }

  std::u16string GetKeepaliveCountText(int keepalive_count) const {
    if (keepalive_count < 0) {
      return n_a_string();
    }
    return base::FormatNumber(keepalive_count);
  }

  const std::u16string& n_a_string() const { return n_a_string_; }
  const std::u16string& backgrounded_string() const {
    return backgrounded_string_;
  }
  const std::u16string& foregrounded_string() const {
    return foregrounded_string_;
  }
  const std::u16string& asterisk_string() const { return asterisk_string_; }

 private:
  // The localized string "N/A".
  const std::u16string n_a_string_;

  // The localized string for a value 0.
  const std::u16string zero_string_;

  // The localized string "Backgrounded" for process priority.
  const std::u16string backgrounded_string_;

  // The localized string "Foregrounded" for process priority.
  const std::u16string foregrounded_string_;

  // The string "*" that is used to show that there exists duplicates in the
  // GPU memory.
  const std::u16string asterisk_string_;
};

////////////////////////////////////////////////////////////////////////////////
// TableSortDescriptor:
////////////////////////////////////////////////////////////////////////////////

TableSortDescriptor::TableSortDescriptor()
    : sorted_column_id(-1), is_ascending(false) {}

TableSortDescriptor::TableSortDescriptor(int col_id, bool ascending)
    : sorted_column_id(col_id), is_ascending(ascending) {}

////////////////////////////////////////////////////////////////////////////////
// TaskManagerTableModel:
////////////////////////////////////////////////////////////////////////////////

TaskManagerTableModel::TaskManagerTableModel(
    TableViewDelegate* delegate,
    DisplayCategory initial_display_category)
    : TaskManagerObserver(
          base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)
              ? base::Seconds(2)
              : kRefreshTime,
          REFRESH_TYPE_NONE),
      table_view_delegate_(delegate),
      table_model_observer_(nullptr),
      stringifier_(new TaskManagerValuesStringifier),
      display_category_(initial_display_category) {
  DCHECK(delegate);
  StartUpdating();
}

TaskManagerTableModel::~TaskManagerTableModel() {
  StopUpdating();

  if (!base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    return;
  }

  // A tab switch isn't performed when the table model closes, so we need to
  // collect the remaining elapsed time in the current tab.
  UpdateOldTabTime(/*old_category=*/display_category_);

  // Record these manually instead of using a loop so that if the enums change
  // this will fail to compile.
  task_manager::RecordTabSwitchEvent(CategoryRecord::kTabsAndExtensions,
                                     tabs_and_ex_total_time_);

  // Note: system_total_time_ is used for both since there is no functional
  // difference between browser & system (they are essentially the same tab).
  // Instead, the data is routed to the platform appropriate bucket.
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_MAC) || BUILDFLAG(IS_LINUX)
  task_manager::RecordTabSwitchEvent(CategoryRecord::kBrowser,
                                     system_total_time_);
#elif BUILDFLAG(IS_CHROMEOS)
  task_manager::RecordTabSwitchEvent(CategoryRecord::kSystem,
                                     system_total_time_);
#endif

  task_manager::RecordTabSwitchEvent(CategoryRecord::kAll, all_total_time_);
}

size_t TaskManagerTableModel::RowCount() {
  return tasks_.size();
}

std::u16string TaskManagerTableModel::GetText(size_t row, int column) {
  if (IsSharedByGroup(column) && !IsTaskFirstInGroup(row)) {
    return std::u16string();
  }

  switch (column) {
    case IDS_TASK_MANAGER_TASK_COLUMN:
      return observed_task_manager()->GetTitle(tasks_[row]);

    case IDS_TASK_MANAGER_PROFILE_NAME_COLUMN:
      return observed_task_manager()->GetProfileName(tasks_[row]);

    case IDS_TASK_MANAGER_NET_COLUMN:
      return stringifier_->GetNetworkUsageText(
          observed_task_manager()->GetProcessTotalNetworkUsage(tasks_[row]));

    case IDS_TASK_MANAGER_CPU_COLUMN:
      return stringifier_->GetCpuUsageText(
          observed_task_manager()->GetPlatformIndependentCPUUsage(tasks_[row]));

    case IDS_TASK_MANAGER_CPU_TIME_COLUMN:
      return stringifier_->GetCpuTimeText(
          observed_task_manager()->GetCpuTime(tasks_[row]));

    case IDS_TASK_MANAGER_START_TIME_COLUMN:
      return stringifier_->GetStartTimeText(
          observed_task_manager()->GetStartTime(tasks_[row]));

    case IDS_TASK_MANAGER_MEM_FOOTPRINT_COLUMN:
      return stringifier_->GetMemoryUsageText(
          observed_task_manager()->GetMemoryFootprintUsage(tasks_[row]), false);

    case IDS_TASK_MANAGER_SWAPPED_MEM_COLUMN:
      return stringifier_->GetMemoryUsageText(
          observed_task_manager()->GetSwappedMemoryUsage(tasks_[row]), false);

    case IDS_TASK_MANAGER_PROCESS_ID_COLUMN:
      if (observed_task_manager()->IsRunningInVM(tasks_[row])) {
        // Don't show the process ID if running inside a VM to avoid confusion
        // over conflicting pids.
        // TODO(b/122992194): Figure out if we need to change this to display
        // something for VM processes.
        return std::u16string();
      }
      return stringifier_->GetProcessIdText(
          observed_task_manager()->GetProcessId(tasks_[row]));

    case IDS_TASK_MANAGER_GDI_HANDLES_COLUMN: {
      int64_t current, peak;
      observed_task_manager()->GetGDIHandles(tasks_[row], &current, &peak);
      return stringifier_->GetWindowsHandlesText(current, peak);
    }

    case IDS_TASK_MANAGER_USER_HANDLES_COLUMN: {
      int64_t current, peak;
      observed_task_manager()->GetUSERHandles(tasks_[row], &current, &peak);
      return stringifier_->GetWindowsHandlesText(current, peak);
    }

    case IDS_TASK_MANAGER_IDLE_WAKEUPS_COLUMN:
      return stringifier_->GetIdleWakeupsText(
          observed_task_manager()->GetIdleWakeupsPerSecond(tasks_[row]));

    case IDS_TASK_MANAGER_HARD_FAULTS_COLUMN:
      return stringifier_->GetHardFaultsText(
          observed_task_manager()->GetHardFaultsPerSecond(tasks_[row]));

    case IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN: {
      blink::WebCacheResourceTypeStats stats;
      if (observed_task_manager()->GetWebCacheStats(tasks_[row], &stats)) {
        return stringifier_->GetWebCacheStatText(stats.images);
      }
      return stringifier_->n_a_string();
    }

    case IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN: {
      blink::WebCacheResourceTypeStats stats;
      if (observed_task_manager()->GetWebCacheStats(tasks_[row], &stats)) {
        return stringifier_->GetWebCacheStatText(stats.scripts);
      }
      return stringifier_->n_a_string();
    }

    case IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN: {
      blink::WebCacheResourceTypeStats stats;
      if (observed_task_manager()->GetWebCacheStats(tasks_[row], &stats)) {
        return stringifier_->GetWebCacheStatText(stats.css_style_sheets);
      }
      return stringifier_->n_a_string();
    }

    case IDS_TASK_MANAGER_VIDEO_MEMORY_COLUMN: {
      bool has_duplicates = false;
      return stringifier_->GetMemoryUsageText(
          observed_task_manager()->GetGpuMemoryUsage(tasks_[row],
                                                     &has_duplicates),
          has_duplicates);
    }

    case IDS_TASK_MANAGER_SQLITE_MEMORY_USED_COLUMN:
      return stringifier_->GetMemoryUsageText(
          observed_task_manager()->GetSqliteMemoryUsed(tasks_[row]), false);

    case IDS_TASK_MANAGER_JAVASCRIPT_MEMORY_ALLOCATED_COLUMN: {
      base::ByteCount v8_allocated, v8_used;
      if (observed_task_manager()->GetV8Memory(tasks_[row], &v8_allocated,
                                               &v8_used)) {
        return stringifier_->FormatAllocatedAndUsedMemory(
            base::ByteCount(v8_allocated), base::ByteCount(v8_used));
      }
      return stringifier_->n_a_string();
    }

    case IDS_TASK_MANAGER_PROCESS_PRIORITY_COLUMN:
      return observed_task_manager()->IsTaskOnBackgroundedProcess(tasks_[row])
                 ? stringifier_->backgrounded_string()
                 : stringifier_->foregrounded_string();

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)
    case IDS_TASK_MANAGER_OPEN_FD_COUNT_COLUMN: {
      const int fd_count = observed_task_manager()->GetOpenFdCount(tasks_[row]);
      return fd_count >= 0 ? base::FormatNumber(fd_count)
                           : stringifier_->n_a_string();
    }
#endif  // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)

    case IDS_TASK_MANAGER_KEEPALIVE_COUNT_COLUMN: {
      return stringifier_->GetKeepaliveCountText(
          observed_task_manager()->GetKeepaliveCount(tasks_[row]));
    }

    default:
      NOTREACHED();
  }
}

ui::ImageModel TaskManagerTableModel::GetIcon(size_t row) {
  return ui::ImageModel::FromImageSkia(
      observed_task_manager()->GetIcon(tasks_[row]));
}

void TaskManagerTableModel::SetObserver(ui::TableModelObserver* observer) {
  table_model_observer_ = observer;
}

int TaskManagerTableModel::CompareValues(size_t row1,
                                         size_t row2,
                                         int column_id) {
  switch (column_id) {
    case IDS_TASK_MANAGER_TASK_COLUMN:
    case IDS_TASK_MANAGER_PROFILE_NAME_COLUMN:
      return ui::TableModel::CompareValues(row1, row2, column_id);

    case IDS_TASK_MANAGER_NET_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetNetworkUsage(tasks_[row1]),
          observed_task_manager()->GetNetworkUsage(tasks_[row2]));

    case IDS_TASK_MANAGER_CPU_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetPlatformIndependentCPUUsage(tasks_[row1]),
          observed_task_manager()->GetPlatformIndependentCPUUsage(
              tasks_[row2]));

    case IDS_TASK_MANAGER_CPU_TIME_COLUMN:
      return ValueCompare(observed_task_manager()->GetCpuTime(tasks_[row1]),
                          observed_task_manager()->GetCpuTime(tasks_[row2]));

    case IDS_TASK_MANAGER_START_TIME_COLUMN:
      return ValueCompare(observed_task_manager()->GetStartTime(tasks_[row1]),
                          observed_task_manager()->GetStartTime(tasks_[row2]));

    case IDS_TASK_MANAGER_MEM_FOOTPRINT_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetMemoryFootprintUsage(tasks_[row1]),
          observed_task_manager()->GetMemoryFootprintUsage(tasks_[row2]));

    case IDS_TASK_MANAGER_SWAPPED_MEM_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetSwappedMemoryUsage(tasks_[row1]),
          observed_task_manager()->GetSwappedMemoryUsage(tasks_[row2]));

    case IDS_TASK_MANAGER_PROCESS_ID_COLUMN: {
      bool vm1 = observed_task_manager()->IsRunningInVM(tasks_[row1]);
      bool vm2 = observed_task_manager()->IsRunningInVM(tasks_[row2]);
      if (vm1 != vm2) {
        return ValueCompare(vm1, vm2);
      }
      return ValueCompare(observed_task_manager()->GetProcessId(tasks_[row1]),
                          observed_task_manager()->GetProcessId(tasks_[row2]));
    }

    case IDS_TASK_MANAGER_GDI_HANDLES_COLUMN: {
      int64_t current1, peak1, current2, peak2;
      observed_task_manager()->GetGDIHandles(tasks_[row1], &current1, &peak1);
      observed_task_manager()->GetGDIHandles(tasks_[row2], &current2, &peak2);
      return ValueCompare(current1, current2);
    }

    case IDS_TASK_MANAGER_USER_HANDLES_COLUMN: {
      int64_t current1, peak1, current2, peak2;
      observed_task_manager()->GetUSERHandles(tasks_[row1], &current1, &peak1);
      observed_task_manager()->GetUSERHandles(tasks_[row2], &current2, &peak2);
      return ValueCompare(current1, current2);
    }

    case IDS_TASK_MANAGER_IDLE_WAKEUPS_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetIdleWakeupsPerSecond(tasks_[row1]),
          observed_task_manager()->GetIdleWakeupsPerSecond(tasks_[row2]));

    case IDS_TASK_MANAGER_HARD_FAULTS_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetHardFaultsPerSecond(tasks_[row1]),
          observed_task_manager()->GetHardFaultsPerSecond(tasks_[row2]));

    case IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN: {
      blink::WebCacheResourceTypeStats stats1;
      blink::WebCacheResourceTypeStats stats2;
      bool row1_stats_valid =
          observed_task_manager()->GetWebCacheStats(tasks_[row1], &stats1);
      bool row2_stats_valid =
          observed_task_manager()->GetWebCacheStats(tasks_[row2], &stats2);
      if (!row1_stats_valid || !row2_stats_valid) {
        return OrderUnavailableValue(row1_stats_valid, row2_stats_valid);
      }

      switch (column_id) {
        case IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN:
          return ValueCompare(stats1.images.size, stats2.images.size);
        case IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN:
          return ValueCompare(stats1.scripts.size, stats2.scripts.size);
        case IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN:
          return ValueCompare(stats1.css_style_sheets.size,
                              stats2.css_style_sheets.size);
        default:
          NOTREACHED();
      }
    }

    case IDS_TASK_MANAGER_VIDEO_MEMORY_COLUMN: {
      bool has_duplicates;
      return ValueCompare(observed_task_manager()->GetGpuMemoryUsage(
                              tasks_[row1], &has_duplicates),
                          observed_task_manager()->GetGpuMemoryUsage(
                              tasks_[row2], &has_duplicates));
    }

    case IDS_TASK_MANAGER_JAVASCRIPT_MEMORY_ALLOCATED_COLUMN: {
      base::ByteCount allocated1, allocated2, used1, used2;
      bool row1_valid = observed_task_manager()->GetV8Memory(
          tasks_[row1], &allocated1, &used1);
      bool row2_valid = observed_task_manager()->GetV8Memory(
          tasks_[row2], &allocated2, &used2);
      if (!row1_valid || !row2_valid) {
        return OrderUnavailableValue(row1_valid, row2_valid);
      }

      return ValueCompare(allocated1, allocated2);
    }

    case IDS_TASK_MANAGER_SQLITE_MEMORY_USED_COLUMN:
      return ValueCompare(
          observed_task_manager()->GetSqliteMemoryUsed(tasks_[row1]),
          observed_task_manager()->GetSqliteMemoryUsed(tasks_[row2]));

    case IDS_TASK_MANAGER_PROCESS_PRIORITY_COLUMN: {
      const bool is_proc1_bg =
          observed_task_manager()->IsTaskOnBackgroundedProcess(tasks_[row1]);
      const bool is_proc2_bg =
          observed_task_manager()->IsTaskOnBackgroundedProcess(tasks_[row2]);
      return BooleanCompare(is_proc1_bg, is_proc2_bg);
    }

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)
    case IDS_TASK_MANAGER_OPEN_FD_COUNT_COLUMN: {
      const int proc1_fd_count =
          observed_task_manager()->GetOpenFdCount(tasks_[row1]);
      const int proc2_fd_count =
          observed_task_manager()->GetOpenFdCount(tasks_[row2]);
      return ValueCompare(proc1_fd_count, proc2_fd_count);
    }
#endif  // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)
    case IDS_TASK_MANAGER_KEEPALIVE_COUNT_COLUMN: {
      return ValueCompare(
          observed_task_manager()->GetKeepaliveCount(tasks_[row1]),
          observed_task_manager()->GetKeepaliveCount(tasks_[row2]));
    }
    default:
      NOTREACHED();
  }
}

std::u16string TaskManagerTableModel::GetAXNameForHeader(
    const std::vector<std::u16string>& visible_column_titles,
    const std::vector<std::u16string>& visible_column_sortable) {
  // Gate the header change for task manager behind feature flag. Clean it up
  // once refreshed task manager is launched.
  // TODO(crbug.com/364926055): Chromium Task Manager Refresh Cleanup.
  if (!base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    return TableModel::GetAXNameForHeader(visible_column_titles,
                                          visible_column_sortable);
  }
  return FormatListToString(visible_column_sortable);
}

std::u16string TaskManagerTableModel::GetAXNameForHeaderCell(
    const std::u16string& visible_column_title,
    const std::u16string& visible_column_sortable) {
  if (!base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    return TableModel::GetAXNameForHeaderCell(visible_column_title,
                                              visible_column_sortable);
  }
  return visible_column_sortable;
}

std::u16string TaskManagerTableModel::GetAXNameForRow(
    size_t row,
    const std::vector<int>& visible_column_ids) {
  // Gate the row change for task manager behind feature flag. Clean it up
  // once refreshed task manager is launched.
  // TODO(crbug.com/364926055): Chromium Task Manager Refresh Cleanup.
  if (!base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    return TableModel::GetAXNameForRow(row, visible_column_ids);
  }

  DCHECK_LT(row, RowCount());
  DCHECK(!visible_column_ids.empty());

  // Holds all visible column values for the `row`.
  std::vector<std::u16string> column_names;
  column_names.reserve(visible_column_ids.size());
  std::ranges::transform(
      visible_column_ids, std::back_inserter(column_names),
      [this, row](const auto& col_id) { return GetText(row, col_id); });
  std::erase_if(column_names,
                [](const auto& column_name) { return column_name.empty(); });

  // Holds all other task titles in the same task group with the 'row'.
  std::vector<std::u16string> other_task_titles;
  if (IsTaskFirstInGroup(row)) {
    const auto current_task = tasks_.begin() + row;
    const base::ProcessId current_process_id =
        observed_task_manager()->GetProcessId(tasks_[row]);
    // Record the end of the column names for the task.
    const auto mismatch_task = std::ranges::find_if_not(
        current_task, tasks_.end(),
        [this, current_process_id](const auto& task_id) {
          return observed_task_manager()->GetProcessId(task_id) ==
                 current_process_id;
        });

    if (mismatch_task - current_task > 1) {
      const TaskIdList group_tasks =
          observed_task_manager()->GetIdsOfTasksSharingSameProcess(tasks_[row]);
      DCHECK(!group_tasks.empty());
      other_task_titles.reserve(group_tasks.size() - 1);
      // If there is at least one task other than the `row` in the same task
      // group existing in `tasks_`, insert the connect text and the title of
      // the other tasks.
      // Add other tasks in the same task group in `other_task_titles` .
      std::ranges::transform(
          current_task + 1, mismatch_task,
          std::back_inserter(other_task_titles), [this](const auto& task_id) {
            return observed_task_manager()->GetTitle(task_id);
          });
    }
  }

  return base::i18n::MessageFormatter::FormatWithNamedArgs(
      l10n_util::GetStringUTF16(IDS_TASK_MANAGER_TASK_GROUP_CONNECT_TEXT),
      "NUM_TASKS", base::checked_cast<int>(other_task_titles.size()),
      "TASK_ROW", FormatListToString(column_names), "OTHER_TASKS",
      FormatListToString(other_task_titles));
}

std::u16string TaskManagerTableModel::FormatListToString(
    base::span<const std::u16string> items) {
  if (items.empty()) {
    return std::u16string();
  }

  std::vector<icu::UnicodeString> strings;
  strings.reserve(items.size());
  for (const auto& item : items) {
    strings.emplace_back(item.data(), item.size());
  }

  UErrorCode status = U_ZERO_ERROR;
  const auto formatter =
      base::WrapUnique(icu::ListFormatter::createInstance(status));
  CHECK(U_SUCCESS(status));

  icu::UnicodeString formatted;
  formatter->format(strings.data(), strings.size(), formatted, status);
  CHECK(U_SUCCESS(status));

  return base::i18n::UnicodeStringToString16(formatted);
}

void TaskManagerTableModel::GetRowsGroupRange(size_t row_index,
                                              size_t* out_start,
                                              size_t* out_length) {
  size_t i = row_index;
  size_t limit = row_index + 1;
  if (!observed_task_manager()->IsRunningInVM(tasks_[row_index])) {
    const base::ProcessId process_id =
        observed_task_manager()->GetProcessId(tasks_[row_index]);
    while (i > 0 &&
           observed_task_manager()->GetProcessId(tasks_[i - 1]) == process_id &&
           !observed_task_manager()->IsRunningInVM(tasks_[i - 1])) {
      --i;
    }
    while (limit < RowCount() &&
           observed_task_manager()->GetProcessId(tasks_[limit]) == process_id &&
           !observed_task_manager()->IsRunningInVM(tasks_[limit])) {
      ++limit;
    }
  }
  *out_start = i;
  *out_length = limit - i;
}

void TaskManagerTableModel::FilterTaskList(std::vector<TaskId>& tasks) {
  std::erase_if(tasks, [this](const TaskId& task_id) {
    // Remove each node whose root doesn't match the Type criteria.
    return !ShouldKeepTask(task_id);
  });
}

void TaskManagerTableModel::OnTaskAdded(TaskId id) {
  if (!search_terms_.empty()) {
    // Update matched process id.
    UpdateMatchedProcessSetById(id);
  }

  // For the table view scrollbar to behave correctly we must inform it that
  // a new task has been added.

  // We will get a newly sorted list from the task manager as opposed to just
  // adding |id| to |tasks_| because we want to keep |tasks_| sorted by proc
  // IDs and then by Task IDs.
  tasks_ = observed_task_manager()->GetTaskIdsList();
  FilterTaskList(tasks_);

  if (!ShouldKeepTask(id)) {
    return;
  }

  if (table_model_observer_) {
    std::vector<TaskId>::difference_type index =
        std::ranges::find(tasks_, id) - tasks_.begin();
    table_model_observer_->OnItemsAdded(index, 1);
  }
}

void TaskManagerTableModel::OnTaskToBeRemoved(TaskId id) {
  if (!search_terms_.empty() && !HasMatchInTasksSharingSameProcess(id)) {
    // Update matched process set if task manager is in search mode.
    matched_process_set_.erase(observed_task_manager()->GetProcessId(id));
  }

  if (!ShouldKeepTask(id)) {
    return;
  }

  auto index = std::ranges::find(tasks_, id);
  if (index == tasks_.end()) {
    return;
  }
  auto removed_index = static_cast<size_t>(index - tasks_.begin());
  tasks_.erase(index);
  if (table_model_observer_) {
    table_model_observer_->OnItemsRemoved(removed_index, 1);
  }
}

void TaskManagerTableModel::OnTasksRefreshed(const TaskIdList& task_ids) {
  OnRefresh(task_ids);
}

void TaskManagerTableModel::OnTasksRefreshedWithBackgroundCalculations(
    const TaskIdList& task_ids) {
  if (base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    OnRefresh(task_ids);
  }
}

void TaskManagerTableModel::ActivateTask(size_t row_index) {
  observed_task_manager()->ActivateTask(tasks_[row_index]);
}

bool TaskManagerTableModel::KillTask(size_t row_index) {
  return observed_task_manager()->KillTask(tasks_[row_index]);
}

void TaskManagerTableModel::UpdateRefreshTypes(int column_id, bool visibility) {
  bool needs_refresh = visibility;
  RefreshType type = REFRESH_TYPE_NONE;
  switch (column_id) {
    case IDS_TASK_MANAGER_PROFILE_NAME_COLUMN:
    case IDS_TASK_MANAGER_TASK_COLUMN:
    case IDS_TASK_MANAGER_PROCESS_ID_COLUMN:
      return;  // The data in these columns do not change.

    case IDS_TASK_MANAGER_NET_COLUMN:
      type = REFRESH_TYPE_NETWORK_USAGE;
      break;

    case IDS_TASK_MANAGER_CPU_COLUMN:
      type = REFRESH_TYPE_CPU;
      break;

    case IDS_TASK_MANAGER_START_TIME_COLUMN:
      type = REFRESH_TYPE_START_TIME;
      break;

    case IDS_TASK_MANAGER_CPU_TIME_COLUMN:
      type = REFRESH_TYPE_CPU_TIME;
      break;

    case IDS_TASK_MANAGER_MEM_FOOTPRINT_COLUMN:
      type = REFRESH_TYPE_MEMORY_FOOTPRINT;
      break;

    case IDS_TASK_MANAGER_SWAPPED_MEM_COLUMN:
      type = REFRESH_TYPE_SWAPPED_MEM;
      if (table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_SWAPPED_MEM_COLUMN)) {
        needs_refresh = true;
      }
      break;

    case IDS_TASK_MANAGER_GDI_HANDLES_COLUMN:
    case IDS_TASK_MANAGER_USER_HANDLES_COLUMN:
      type = REFRESH_TYPE_HANDLES;
      if (table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_GDI_HANDLES_COLUMN) ||
          table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_USER_HANDLES_COLUMN)) {
        needs_refresh = true;
      }
      break;

    case IDS_TASK_MANAGER_IDLE_WAKEUPS_COLUMN:
      type = REFRESH_TYPE_IDLE_WAKEUPS;
      break;

    case IDS_TASK_MANAGER_HARD_FAULTS_COLUMN:
      type = REFRESH_TYPE_HARD_FAULTS;
      break;

    case IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN:
    case IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN:
      type = REFRESH_TYPE_WEBCACHE_STATS;
      if (table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_WEBCORE_IMAGE_CACHE_COLUMN) ||
          table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_WEBCORE_SCRIPTS_CACHE_COLUMN) ||
          table_view_delegate_->IsColumnVisible(
              IDS_TASK_MANAGER_WEBCORE_CSS_CACHE_COLUMN)) {
        needs_refresh = true;
      }
      break;

    case IDS_TASK_MANAGER_VIDEO_MEMORY_COLUMN:
      type = REFRESH_TYPE_GPU_MEMORY;
      break;

    case IDS_TASK_MANAGER_SQLITE_MEMORY_USED_COLUMN:
      type = REFRESH_TYPE_SQLITE_MEMORY;
      break;

    case IDS_TASK_MANAGER_JAVASCRIPT_MEMORY_ALLOCATED_COLUMN:
      type = REFRESH_TYPE_V8_MEMORY;
      break;

    case IDS_TASK_MANAGER_PROCESS_PRIORITY_COLUMN:
      type = REFRESH_TYPE_PRIORITY;
      break;

    case IDS_TASK_MANAGER_KEEPALIVE_COUNT_COLUMN:
      type = REFRESH_TYPE_KEEPALIVE_COUNT;
      break;

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)
    case IDS_TASK_MANAGER_OPEN_FD_COUNT_COLUMN:
      type = REFRESH_TYPE_FD_COUNT;
      break;
#endif  // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_MAC)

    default:
      NOTREACHED();
  }

  if (needs_refresh) {
    AddRefreshType(type);
  } else {
    RemoveRefreshType(type);
  }
}

bool TaskManagerTableModel::IsTaskKillable(size_t row_index) const {
  return observed_task_manager()->IsTaskKillable(tasks_[row_index]);
}

void TaskManagerTableModel::RetrieveSavedColumnsSettingsAndUpdateTable(
    bool default_sorted_column_to_cpu) {
  if (!g_browser_process->local_state()) {
    return;
  }

  const base::Value::Dict& dictionary =
      g_browser_process->local_state()->GetDict(
          prefs::kTaskManagerColumnVisibility);

  // Do a best effort of retrieving the correct settings from the local state.
  // Use the default settings of the value if it fails to be retrieved.
  const std::string* sorted_col_id = dictionary.FindString(kSortColumnIdKey);
  bool sort_is_ascending =
      dictionary.FindBool(kSortIsAscendingKey).value_or(true);

  for (size_t i = 0; i < kColumnsSize; ++i) {
    const int col_id = kColumns[i].id;
    const std::string col_id_key(GetColumnIdAsString(col_id));

    if (col_id_key.empty()) {
      continue;
    }

    bool col_visibility = dictionary.FindBoolByDottedPath(col_id_key)
                              .value_or(kColumns[i].default_visibility);

    // If the above FindBoolByDottedPath() fails, the |col_visibility| remains
    // at the default visibility.
    columns_settings_.SetByDottedPath(col_id_key, col_visibility);
    table_view_delegate_->SetColumnVisibility(col_id, col_visibility);
    UpdateRefreshTypes(col_id, col_visibility);

    if (col_visibility) {
      if (sorted_col_id && *sorted_col_id == col_id_key) {
        table_view_delegate_->SetSortDescriptor(
            TableSortDescriptor(col_id, sort_is_ascending));
      } else if (default_sorted_column_to_cpu && !sorted_col_id &&
                 col_id_key ==
                     GetColumnIdAsString(IDS_TASK_MANAGER_CPU_COLUMN)) {
        // If there is no user selected column, the sorting default should be
        // the CPU column if it's visible.
        table_view_delegate_->SetSortDescriptor(
            TableSortDescriptor(IDS_TASK_MANAGER_CPU_COLUMN, false));
      }
    }
  }
}

void TaskManagerTableModel::StoreColumnsSettings() {
  PrefService* local_state = g_browser_process->local_state();
  if (!local_state) {
    return;
  }

  ScopedDictPrefUpdate dict_update(local_state,
                                   prefs::kTaskManagerColumnVisibility);

  for (const auto item : columns_settings_) {
    dict_update->SetByDottedPath(item.first, item.second.Clone());
  }

  // Store the current sort status to be restored again at startup.
  if (!table_view_delegate_->IsTableSorted()) {
    dict_update->Set(kSortColumnIdKey, "");
  } else {
    const auto& sort_descriptor = table_view_delegate_->GetSortDescriptor();
    dict_update->Set(kSortColumnIdKey,
                     GetColumnIdAsString(sort_descriptor.sorted_column_id));
    dict_update->Set(kSortIsAscendingKey, sort_descriptor.is_ascending);
  }
}

void TaskManagerTableModel::ToggleColumnVisibility(int column_id) {
  bool new_visibility = !table_view_delegate_->IsColumnVisible(column_id);
  if (table_view_delegate_->SetColumnVisibility(column_id, new_visibility)) {
    columns_settings_.SetByDottedPath(GetColumnIdAsString(column_id),
                                      new_visibility);
    UpdateRefreshTypes(column_id, new_visibility);
  }
}

std::optional<size_t> TaskManagerTableModel::GetRowForWebContents(
    content::WebContents* web_contents) {
  TaskId task_id =
      observed_task_manager()->GetTaskIdForWebContents(web_contents);
  auto index = std::ranges::find(tasks_, task_id);
  if (index == tasks_.end()) {
    return std::nullopt;
  }
  return static_cast<size_t>(index - tasks_.begin());
}

void TaskManagerTableModel::StartUpdating() {
  TaskManagerInterface::GetTaskManager()->AddObserver(this);
  OnRefresh(observed_task_manager()->GetTaskIdsList());

  // In order for the scrollbar of the TableView to work properly on startup of
  // the task manager, we must invoke TableModelObserver::OnModelChanged() which
  // in turn will invoke TableView::NumRowsChanged(). This will adjust the
  // vertical scrollbar correctly. https://crbug.com/40449918.
  if (table_model_observer_) {
    table_model_observer_->OnModelChanged();
  }
}

void TaskManagerTableModel::StopUpdating() {
  observed_task_manager()->RemoveObserver(this);
}

void TaskManagerTableModel::OnRefresh(const TaskIdList& task_ids) {
  tasks_ = task_ids;
  FilterTaskList(tasks_);
  if (table_model_observer_) {
    table_model_observer_->OnItemsChanged(0, RowCount());
  }
}

bool TaskManagerTableModel::IsTaskFirstInGroup(size_t row_index) const {
  if (row_index == 0) {
    return true;
  }

  if (observed_task_manager()->GetProcessId(tasks_[row_index - 1]) !=
      observed_task_manager()->GetProcessId(tasks_[row_index])) {
    return true;
  }

  if (observed_task_manager()->IsRunningInVM(tasks_[row_index - 1]) !=
      observed_task_manager()->IsRunningInVM(tasks_[row_index])) {
    return true;
  }

  return false;
}

bool TaskManagerTableModel::FetchTaskTypes(TaskId child_task_id,
                                           Task::Type& out_type,
                                           Task::SubType& out_subtype) const {
  const TaskId root = observed_task_manager()->GetRootTaskId(child_task_id);
  if (!observed_task_manager()->IsTaskValid(root)) {
    return false;
  }

  out_type = observed_task_manager()->GetType(root);
  out_subtype = observed_task_manager()->GetSubType(root);
  return true;
}

bool TaskManagerTableModel::ShouldKeepTaskForSupportedType(
    TaskId task_id) const {
  Task::Type type;
  Task::SubType subtype;

  if (!FetchTaskTypes(task_id, type, subtype)) {
    // crbug.com/396002122: It is possible that the root task id is not
    // valid/tracked anymore, so discard this task.
    return false;
  }

  return ShouldKeepTaskForTabsAndExtensions(type, subtype) ||
         ShouldKeepTaskForSystem(type, subtype);
}

bool TaskManagerTableModel::ShouldKeepTask(TaskId task_id) const {
  // TODO(crbug.com/364926055): Remove when the refreshed Task Manager launches.
  // Used for backward compatibility with the prod. task manager.
  if (!base::FeatureList::IsEnabled(features::kTaskManagerDesktopRefresh)) {
    return true;
  }

  if (!search_terms_.empty() &&
      !matched_process_set_.contains(
          observed_task_manager()->GetProcessId(task_id))) {
    // In refreshed task manager, task should not be kept if the task title does
    // not match the search term or not in the same task group with the matched
    // tasks.
    return false;
  }

  Task::Type type;
  Task::SubType subtype;

  // Keep any TaskId iff the task that spawned it (root node) has a type that
  // matches the current category.
  if (!FetchTaskTypes(task_id, type, subtype)) {
    // crbug.com/396002122: It is possible that the root task id is not
    // valid/tracked anymore, so discard this task.
    return false;
  }

  switch (display_category_) {
    case DisplayCategory::kTabsAndExtensions:
      return ShouldKeepTaskForTabsAndExtensions(type, subtype);
    case DisplayCategory::kSystem:
      return ShouldKeepTaskForSystem(type, subtype);
    case DisplayCategory::kAll:
      return true;
    default:
      NOTREACHED();
  }
}

bool TaskManagerTableModel::HasMatchInTasksSharingSameProcess(
    TaskId task_id) const {
  if (tasks_.empty()) {
    return false;
  }

  for (TaskId id :
       observed_task_manager()->GetIdsOfTasksSharingSameProcess(task_id)) {
    if (base::i18n::StringSearchIgnoringCaseAndAccents(
            search_terms_, observed_task_manager()->GetTitle(id),
            /*match_index=*/nullptr, /*match_length=*/nullptr) &&
        std::ranges::find(tasks_, id) != tasks_.end()) {
      // There is at least one matched task in task group, we need to
      // keep it.
      return true;
    }
  }
  return false;
}

void TaskManagerTableModel::UpdateMatchedProcessSet() {
  matched_process_set_.clear();

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

  for (TaskId task_id : observed_task_manager()->GetTaskIdsList()) {
    UpdateMatchedProcessSetById(task_id);
  }
}

void TaskManagerTableModel::UpdateMatchedProcessSetById(TaskId task_id) {
  // Excludes the task from search term match if it does not fall in any
  // supported category.
  if ((display_category_ == DisplayCategory::kAll ||
       ShouldKeepTaskForSupportedType(task_id)) &&
      base::i18n::StringSearchIgnoringCaseAndAccents(
          search_terms_, observed_task_manager()->GetTitle(task_id),
          /*match_index=*/nullptr, /*match_length=*/nullptr)) {
    matched_process_set_.insert(observed_task_manager()->GetProcessId(task_id));
  }
}

void TaskManagerTableModel::UpdateOldTabTime(DisplayCategory old_category) {
  // Add the elapsed time in the old category to the total time spent in this
  // session.
  const auto end_time = base::TimeTicks::Now();
  switch (old_category) {
    case DisplayCategory::kTabsAndExtensions:
      tabs_and_ex_total_time_ += (end_time - tabs_and_ex_start_time_);
      break;
    case DisplayCategory::kSystem:
      system_total_time_ += (end_time - system_start_time_);
      break;
    case DisplayCategory::kAll:
      all_total_time_ += (end_time - all_start_time_);
      break;
    default:
      NOTREACHED();
  }
}

void TaskManagerTableModel::StartNewTabTime(DisplayCategory new_category) {
  // Reset the start time for the new category.
  const auto end_time = base::TimeTicks::Now();
  switch (new_category) {
    case DisplayCategory::kTabsAndExtensions:
      tabs_and_ex_start_time_ = end_time;
      break;
    case DisplayCategory::kSystem:
      system_start_time_ = end_time;
      break;
    case DisplayCategory::kAll:
      all_start_time_ = end_time;
      break;
    default:
      NOTREACHED();
  }
}

bool TaskManagerTableModel::UpdateModel(const DisplayCategory display_category,
                                        std::u16string_view search_term) {
  if (search_terms_ == search_term && display_category_ == display_category) {
    // Early return if no real change happens.
    return false;
  }

  // If there is a category switch, log the time spent. Used for UMA metrics.
  if (display_category_ != display_category) {
    UpdateOldTabTime(display_category_);
    StartNewTabTime(display_category);
  }

  search_terms_ = std::u16string(search_term);
  display_category_ = display_category;

  // Precalculate matched processes for search terms.
  UpdateMatchedProcessSet();

  if (!table_model_observer_) {
    return false;
  }

  // Task list which will be used for filter logic.
  const auto task_list = observed_task_manager()->GetTaskIdsList();

  // The final task list after applying the filter logic. It will be used to
  // find the insert position for the new task in the final list.
  auto filtered_task_list = task_list;
  FilterTaskList(filtered_task_list);

  for (TaskId id : task_list) {
    auto filtered_iter = std::ranges::find(filtered_task_list, id);
    bool should_keep_task = filtered_iter != filtered_task_list.end();
    // Indicate if the task is in current task list.
    auto task_iter = std::ranges::find(tasks_, id);
    bool task_id_exists = task_iter != tasks_.end();
    if (should_keep_task == task_id_exists) {
      // The task already displays as the filter logic.
      // Case 1 : The task in the complete task list which matches the filter
      // logic already exists in current task list.
      // Case 2 : The task in the complete task list which does not match  the
      // filter logic does not exist in current task list.
      continue;
    }

    if (should_keep_task) {
      // Need to find a place to insert the task and update the table model.
      std::vector<TaskId>::difference_type index =
          filtered_iter - filtered_task_list.begin();
      CHECK_LE(static_cast<size_t>(index), tasks_.size())
          << " out of bounds insert index " << index;
      tasks_.insert(tasks_.begin() + index, id);
      table_model_observer_->OnItemsAdded(index, 1);
    } else {
      // Need to remove the task and update the table model.
      auto removed_index = static_cast<size_t>(task_iter - tasks_.begin());
      tasks_.erase(task_iter);
      table_model_observer_->OnItemsRemoved(removed_index, 1);
    }
  }
  return true;
}

}  // namespace task_manager