// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_BASE_INTERACTION_INTERACTION_TEST_UTIL_H_
#define UI_BASE_INTERACTION_INTERACTION_TEST_UTIL_H_

#include <memory>
#include <vector>

#include "build/build_config.h"
#include "ui/base/interaction/element_tracker.h"

#if !BUILDFLAG(IS_IOS)
#include "ui/base/accelerators/accelerator.h"
#include "ui/events/keycodes/keyboard_codes.h"
#endif

namespace ui::test {

// Describes the result of a trying to perform a specific action as part of a
// test. Returned by individual functions and action simulators (see
// `InteractionTestUtil::Simulator` below).
enum class [[nodiscard]] ActionResult {
  // Indicates that the code did not know how to perform the action on the
  // requested target. In the case of an action simulator, other simulators
  // should be tried instead. Otherwise, treat as failure.
  kNotAttempted,

  // Indicates that the action succeeded.
  kSucceeded,

  // Indicates that the code *does* know how to perform the action on the
  // requested target, attempted to do so, and failed. No further attempts at
  // performing the action should be made.
  kFailed,

  // Indicates that the code *does* know how to perform the action, but
  // recognized that it would not succeed DUE TO A KNOWN ISSUE OR
  // INCOMPATIBILITY in the current platform, build, or job environment.
  //
  // An action that fails unexpectedly should always return kFailed instead.
  //
  // Code that returns this value should log or document the exact circumstances
  // that lead to the known incompatibility.
  //
  // No further attempts at performing the action should be made. Should be
  // treated as failure by default.
  kKnownIncompatible
};

// Platform- and framework-independent utility for delegating specific common
// actions to framework-specific handlers. Use so you can write your
// interaction tests without having to worry about framework specifics.
//
// Simulators are checked in the reverse order they are added, so if simulators
// are added in the order from more general to more specific, the more specific
// simulators are always checked first.
//
// Example usage:
//
// class MyTest {
//   void SetUp() override {
//     test_util_.AddSimulator(
//         std::make_unique<InteractionTestUtilSimulatorViews>());
// #if BUILDFLAG(IS_MAC)
//     test_util_.AddSimulator(
//         std::make_unique<InteractionTestUtilSimulatorMac>());
// #endif
//     ...
//   }
//   InteractionTestUtil test_util_;
// };
//
// TEST_F(MyTest, TestClickButton) {
//   ...
//   step.SetStartCallback(base::BindLambdaForTesting([&] (
//       InteractionSequence* seq, TrackedElement* element) {
//     ActionResult result = test_util_.PressButton(element);
//     if (result == ActionResult::kError)
//       seq->FailForTesting();
//     else if (result = ActionResult::kNotSupportedOnThisPlatform)
//       seq->SkipForTesting();
//   }))
//   ...
// }
//
class InteractionTestUtil {
 public:
  // Indicates the type of input we want to apply to an element. Default in most
  // cases is `kDontCare` which will use the most reliable form of input (or may
  // even call code that directly simulates e.g. a button press).
  //
  // Only use values other than `kDontCare` if you REALLY want to test a
  // specific mode of input, as not all inputs will be supported for all
  // frameworks or platforms.
  enum class InputType {
    // Simulate the input in the most reliable way, which could be through
    // sending an input event or calling code that directly simulates the
    // interaction.
    kDontCare,
    // Simulate the input explicitly via mouse events.
    kMouse,
    // Simulate the input explicitly via kayboard events.
    kKeyboard,
    // Simulate the input explicitly via touch events.
    kTouch,
    // If values are added to the enumeration, update this value.
    kMaxValue = kTouch
  };

  // How should text be sent to a text input?
  enum class TextEntryMode {
    // Replaces all of the existing text with the new text.
    kReplaceAll,
    // Inserts the new text at the current cursor position, replacing any
    // existing selection.
    kInsertOrReplace,
    // Appends the new text to the end of the existing text.
    kAppend
  };

  // Provides framework-agnostic ways to send common input to the UI, such as
  // clicking buttons, typing text, etc.
  //
  // Framework-specific implementations will need to be provided to each
  // InteractionTestUtil instance you are using for testing.
  class Simulator {
   public:
    Simulator() = default;
    virtual ~Simulator() = default;
    Simulator(const Simulator&) = delete;
    void operator=(const Simulator&) = delete;

    using InputType = InteractionTestUtil::InputType;
    using TextEntryMode = InteractionTestUtil::TextEntryMode;

    // Tries to press `element` as if it is a button. Returns false if `element`
    // is an unsupported type or if `input_type` is not supported.
    virtual ActionResult PressButton(TrackedElement* element,
                                     InputType input_type);

    // Tries to select `element` as if it is a menu item. Returns false if
    // `element` is an unsupported type or if `input_type` is not supported.
    virtual ActionResult SelectMenuItem(TrackedElement* element,
                                        InputType input_type);

    // Triggers the default action of the target element, which is typically
    // whatever happens when the user clicks/taps it. If `element` is a button
    // or menu item, prefer PressButton() or SelectMenuItem() instead.
    virtual ActionResult DoDefaultAction(TrackedElement* element,
                                         InputType input_type);

    // Tries to select tab `index` in `tab_collection`. The collection could be
    // a tabbed pane, browser/tabstrip, or similar. Note that `index` is
    // zero-indexed. The index after the selection is verified; if for whatever
    // reason it should not be `index`, specify
    // `expected_index_after_selection`.
    virtual ActionResult SelectTab(
        TrackedElement* tab_collection,
        size_t index,
        InputType input_type,
        std::optional<size_t> expected_index_after_selection);

    // Tries to select item `index` in `dropdown`. The collection could be
    // a listbox, combobox, or similar. Note that `index` is zero-indexed.
    virtual ActionResult SelectDropdownItem(TrackedElement* dropdown,
                                            size_t index,
                                            InputType input_type);

    // Sets or modifies the text of a text box, editable combobox, etc.
    virtual ActionResult EnterText(TrackedElement* element,
                                   std::u16string text,
                                   TextEntryMode mode);

    // Activates the surface containing `element`.
    virtual ActionResult ActivateSurface(TrackedElement* element);

    // Focuses `element` within its surface. Does not necessarily activate the
    // surface. Note that on some platforms, `element` may not actually report
    // as focused until its surface is subsequently activated.
    virtual ActionResult FocusElement(TrackedElement* element);

#if !BUILDFLAG(IS_IOS)

    // Sends the given accelerator to the surface containing the element.
    virtual ActionResult SendAccelerator(TrackedElement* element,
                                         Accelerator accelerator);

    // Sends keypress with `key` and `flags` to `element` or its surface.
    virtual ActionResult SendKeyPress(TrackedElement* element,
                                      KeyboardCode key,
                                      int flags);

#endif  // !BUILDFLAG(IS_IOS)

    // Sends a "confirm" input to `element`, e.g. a RETURN keypress.
    virtual ActionResult Confirm(TrackedElement* element);
  };

  InteractionTestUtil();
  virtual ~InteractionTestUtil();
  InteractionTestUtil(const InteractionTestUtil&) = delete;
  void operator=(const InteractionTestUtil&) = delete;

  // Adds an input simulator for a specific framework.
  template <class T>
  T* AddSimulator(std::unique_ptr<T> simulator) {
    T* const result = simulator.get();
    simulators_.emplace_back(std::move(simulator));
    return result;
  }

  // Simulate a button press on `element`. Will fail if `element` is not a
  // button or if `input_type` is not supported.
  ActionResult PressButton(TrackedElement* element,
                           InputType input_type = InputType::kDontCare);

  // Simulate the menu item `element` being selected by the user. Will fail if
  // `element` is not a menu item or if `input_type` is not supported.
  ActionResult SelectMenuItem(TrackedElement* element,
                              InputType input_type = InputType::kDontCare);

  // Simulate selecting the `index`-th tab (zero-indexed) of `tab_collection`.
  // Will fail if the target object is not a supported type, if `index` is out
  // of bounds, or if `input_type` is not supported. The index after the
  // selection will be verified; if for whatever reason it should not be
  // `index`, specify `expected_index_after_selection`.
  ActionResult SelectTab(
      TrackedElement* tab_collection,
      size_t index,
      InputType input_type = InputType::kDontCare,
      std::optional<size_t> expected_index_after_selection = std::nullopt);

  // Simulate selecting item `index` in `dropdown`. The collection could be
  // a listbox, combobox, or similar. Will fail if the target object is not a
  // supported type, if `index` is out of bounds, or if `input_type` is not
  // supported.
  //
  // Note that if `input_type` is kDontCare, the approach with the broadest
  // possible compatibility will be used, possibly bypassing the dropdown menu
  // associated with the element. This is because dropdown menus vary in
  // implementation across platforms and can be a source of flakiness. Options
  // other than kDontCare may not be supported on all platforms for this reason;
  // if they are not, an error message will be printed and the test will fail.
  ActionResult SelectDropdownItem(TrackedElement* dropdown,
                                  size_t index,
                                  InputType input_type = InputType::kDontCare);

  // Simulate the default action for `element` - typically whatever happens when
  // the user clicks or taps on it. Will fail if `input_type` is not supported.
  // Prefer PressButton() for buttons and SelectMenuItem() for menu items.
  ActionResult DoDefaultAction(TrackedElement* element,
                               InputType input_type = InputType::kDontCare);

  // Sets or modifies the text of a text box, editable combobox, etc. `text` is
  // the text to enter, and `mode` specifies how it should be entered. Default
  // is replace existing text.
  ActionResult EnterText(TrackedElement* element,
                         std::u16string text,
                         TextEntryMode mode = TextEntryMode::kReplaceAll);

  // Activates the surface containing `element`. Prefer to use only in
  // single-process test fixtures like interactive_ui_tests, especially for
  // browser windows (as bringing a browser window to the front may require some
  // very aggressive system calls in certain cases and on certain platforms).
  ActionResult ActivateSurface(TrackedElement* element);

  // Focuses `element` within its surface. Does not necessarily activate the
  // surface. Note that on some platforms, `element` may not actually report as
  // focused until its surface is subsequently activated.
  ActionResult FocusElement(TrackedElement* element);

#if !BUILDFLAG(IS_IOS)

  // Sends `accelerator` to the surface containing `element`. May not work if
  // the surface is not active. Prefer to use only in single-process test
  // fixtures like interactive_ui_tests, especially for app/browser
  // accelerators.
  ActionResult SendAccelerator(TrackedElement* element,
                               Accelerator accelerator);

  // Sends key press `key` with `flags` to `element` or its surface.
  ActionResult SendKeyPress(TrackedElement* element,
                            KeyboardCode key,
                            int flags);

#endif  // !BUILDFLAG(IS_IOS)

  // Sends a "confirm" input to `element`, e.g. a RETURN keypress.
  ActionResult Confirm(TrackedElement* element);

 private:
  // The list of known simulators.
  std::vector<std::unique_ptr<Simulator>> simulators_;
};

void PrintTo(InteractionTestUtil::InputType input_type, std::ostream* os);

std::ostream& operator<<(std::ostream& os,
                         InteractionTestUtil::InputType input_type);

}  // namespace ui::test

#endif  // UI_BASE_INTERACTION_INTERACTION_TEST_UTIL_H_