// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'dart:io';

import 'package:flutter/services.dart';
import 'test_async_utils.dart';

/// A class that serves as a namespace for a bunch of keyboard-key generation
/// utilities.
class KeyEventSimulator {
  // Look up a synonym key, and just return the left version of it.
  static LogicalKeyboardKey _getKeySynonym(LogicalKeyboardKey origKey) {
    if (origKey == LogicalKeyboardKey.shift) {
      return LogicalKeyboardKey.shiftLeft;
    }
    if (origKey == LogicalKeyboardKey.alt) {
      return LogicalKeyboardKey.altLeft;
    }
    if (origKey == LogicalKeyboardKey.meta) {
      return LogicalKeyboardKey.metaLeft;
    }
    if (origKey == LogicalKeyboardKey.control) {
      return LogicalKeyboardKey.controlLeft;
    }
    return origKey;
  }

  static bool _osIsSupported(String platform) {
    switch (platform) {
      case 'android':
      case 'fuchsia':
      case 'macos':
      case 'linux':
        return true;
    }
    return false;
  }

  static int _getScanCode(LogicalKeyboardKey key, String platform) {
    assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');
    int scanCode;
    Map<int, PhysicalKeyboardKey> map;
    switch (platform) {
      case 'android':
        map = kAndroidToPhysicalKey;
        break;
      case 'fuchsia':
        map = kFuchsiaToPhysicalKey;
        break;
      case 'macos':
        map = kMacOsToPhysicalKey;
        break;
      case 'linux':
        map = kLinuxToPhysicalKey;
        break;
    }
    for (int code in map.keys) {
      if (key.debugName == map[code].debugName) {
        scanCode = code;
        break;
      }
    }
    return scanCode;
  }

  static int _getKeyCode(LogicalKeyboardKey key, String platform) {
    assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');
    int keyCode;
    Map<int, LogicalKeyboardKey> map;
    switch (platform) {
      case 'android':
        map = kAndroidToLogicalKey;
        break;
      case 'fuchsia':
        map = kFuchsiaToLogicalKey;
        break;
      case 'macos':
      // macOS doesn't do key codes, just scan codes.
        return null;
      case 'linux':
        map = kGlfwToLogicalKey;
        break;
    }
    for (int code in map.keys) {
      if (key.debugName == map[code].debugName) {
        keyCode = code;
        break;
      }
    }
    return keyCode;
  }

  /// Get a raw key data map given a [LogicalKeyboardKey] and a platform.
  static Map<String, dynamic> getKeyData(LogicalKeyboardKey key, {String platform, bool isDown = true}) {
    assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');

    key = _getKeySynonym(key);

    assert(key.debugName != null);
    final int keyCode = platform == 'macos' ? -1 : _getKeyCode(key, platform);
    assert(platform == 'macos' || keyCode != null, 'Key $key not found in $platform keyCode map');
    final int scanCode = _getScanCode(key, platform);
    assert(scanCode != null, 'Physical key for $key not found in $platform scanCode map');

    final Map<String, dynamic> result = <String, dynamic>{
      'type': isDown ? 'keydown' : 'keyup',
      'keymap': platform,
      'character': key.keyLabel,
    };

    switch (platform) {
      case 'android':
        result['keyCode'] = keyCode;
        result['codePoint'] = key.keyLabel?.codeUnitAt(0);
        result['scanCode'] = scanCode;
        result['metaState'] = _getAndroidModifierFlags(key, isDown);
        break;
      case 'fuchsia':
        result['hidUsage'] = key.keyId & LogicalKeyboardKey.hidPlane != 0 ? key.keyId & LogicalKeyboardKey.valueMask : null;
        result['codePoint'] = key.keyLabel?.codeUnitAt(0);
        result['modifiers'] = _getFuchsiaModifierFlags(key, isDown);
        break;
      case 'linux':
        result['toolkit'] = 'glfw';
        result['keyCode'] = keyCode;
        result['scanCode'] = scanCode;
        result['modifiers'] = _getGlfwModifierFlags(key, isDown);
        break;
      case 'macos':
        result['keyCode'] = scanCode;
        result['characters'] = key.keyLabel;
        result['charactersIgnoringModifiers'] = key.keyLabel;
        result['modifiers'] = _getMacOsModifierFlags(key, isDown);
        break;
    }
    return result;
  }

  static int _getAndroidModifierFlags(LogicalKeyboardKey newKey, bool isDown) {
    int result = 0;
    final Set<LogicalKeyboardKey> pressed = RawKeyboard.instance.keysPressed;
    if (isDown) {
      pressed.add(newKey);
    } else {
      pressed.remove(newKey);
    }
    if (pressed.contains(LogicalKeyboardKey.shiftLeft)) {
      result |= RawKeyEventDataAndroid.modifierLeftShift | RawKeyEventDataAndroid.modifierShift;
    }
    if (pressed.contains(LogicalKeyboardKey.shiftRight)) {
      result |= RawKeyEventDataAndroid.modifierRightShift | RawKeyEventDataAndroid.modifierShift;
    }
    if (pressed.contains(LogicalKeyboardKey.metaLeft)) {
      result |= RawKeyEventDataAndroid.modifierLeftMeta | RawKeyEventDataAndroid.modifierMeta;
    }
    if (pressed.contains(LogicalKeyboardKey.metaRight)) {
      result |= RawKeyEventDataAndroid.modifierRightMeta | RawKeyEventDataAndroid.modifierMeta;
    }
    if (pressed.contains(LogicalKeyboardKey.controlLeft)) {
      result |= RawKeyEventDataAndroid.modifierLeftControl | RawKeyEventDataAndroid.modifierControl;
    }
    if (pressed.contains(LogicalKeyboardKey.controlRight)) {
      result |= RawKeyEventDataAndroid.modifierRightControl | RawKeyEventDataAndroid.modifierControl;
    }
    if (pressed.contains(LogicalKeyboardKey.altLeft)) {
      result |= RawKeyEventDataAndroid.modifierLeftAlt | RawKeyEventDataAndroid.modifierAlt;
    }
    if (pressed.contains(LogicalKeyboardKey.altRight)) {
      result |= RawKeyEventDataAndroid.modifierRightAlt | RawKeyEventDataAndroid.modifierAlt;
    }
    if (pressed.contains(LogicalKeyboardKey.fn)) {
      result |= RawKeyEventDataAndroid.modifierFunction;
    }
    if (pressed.contains(LogicalKeyboardKey.scrollLock)) {
      result |= RawKeyEventDataAndroid.modifierScrollLock;
    }
    if (pressed.contains(LogicalKeyboardKey.numLock)) {
      result |= RawKeyEventDataAndroid.modifierNumLock;
    }
    if (pressed.contains(LogicalKeyboardKey.capsLock)) {
      result |= RawKeyEventDataAndroid.modifierCapsLock;
    }
    return result;
  }

  static int _getGlfwModifierFlags(LogicalKeyboardKey newKey, bool isDown) {
    int result = 0;
    final Set<LogicalKeyboardKey> pressed = RawKeyboard.instance.keysPressed;
    if (isDown) {
      pressed.add(newKey);
    } else {
      pressed.remove(newKey);
    }
    if (pressed.contains(LogicalKeyboardKey.shiftLeft) || pressed.contains(LogicalKeyboardKey.shiftRight)) {
      result |= GLFWKeyHelper.modifierShift;
    }
    if (pressed.contains(LogicalKeyboardKey.metaLeft) || pressed.contains(LogicalKeyboardKey.metaRight)) {
      result |= GLFWKeyHelper.modifierMeta;
    }
    if (pressed.contains(LogicalKeyboardKey.controlLeft) || pressed.contains(LogicalKeyboardKey.controlRight)) {
      result |= GLFWKeyHelper.modifierControl;
    }
    if (pressed.contains(LogicalKeyboardKey.altLeft) || pressed.contains(LogicalKeyboardKey.altRight)) {
      result |= GLFWKeyHelper.modifierAlt;
    }
    if (pressed.contains(LogicalKeyboardKey.capsLock)) {
      result |= GLFWKeyHelper.modifierCapsLock;
    }
    return result;
  }

  static int _getFuchsiaModifierFlags(LogicalKeyboardKey newKey, bool isDown) {
    int result = 0;
    final Set<LogicalKeyboardKey> pressed = RawKeyboard.instance.keysPressed;
    if (isDown) {
      pressed.add(newKey);
    } else {
      pressed.remove(newKey);
    }
    if (pressed.contains(LogicalKeyboardKey.shiftLeft)) {
      result |= RawKeyEventDataFuchsia.modifierLeftShift;
    }
    if (pressed.contains(LogicalKeyboardKey.shiftRight)) {
      result |= RawKeyEventDataFuchsia.modifierRightShift;
    }
    if (pressed.contains(LogicalKeyboardKey.metaLeft)) {
      result |= RawKeyEventDataFuchsia.modifierLeftMeta;
    }
    if (pressed.contains(LogicalKeyboardKey.metaRight)) {
      result |= RawKeyEventDataFuchsia.modifierRightMeta;
    }
    if (pressed.contains(LogicalKeyboardKey.controlLeft)) {
      result |= RawKeyEventDataFuchsia.modifierLeftControl;
    }
    if (pressed.contains(LogicalKeyboardKey.controlRight)) {
      result |= RawKeyEventDataFuchsia.modifierRightControl;
    }
    if (pressed.contains(LogicalKeyboardKey.altLeft)) {
      result |= RawKeyEventDataFuchsia.modifierLeftAlt;
    }
    if (pressed.contains(LogicalKeyboardKey.altRight)) {
      result |= RawKeyEventDataFuchsia.modifierRightAlt;
    }
    if (pressed.contains(LogicalKeyboardKey.capsLock)) {
      result |= RawKeyEventDataFuchsia.modifierCapsLock;
    }
    return result;
  }

  static int _getMacOsModifierFlags(LogicalKeyboardKey newKey, bool isDown) {
    int result = 0;
    final Set<LogicalKeyboardKey> pressed = RawKeyboard.instance.keysPressed;
    if (isDown) {
      pressed.add(newKey);
    } else {
      pressed.remove(newKey);
    }
    if (pressed.contains(LogicalKeyboardKey.shiftLeft)) {
      result |= RawKeyEventDataMacOs.modifierLeftShift | RawKeyEventDataMacOs.modifierShift;
    }
    if (pressed.contains(LogicalKeyboardKey.shiftRight)) {
      result |= RawKeyEventDataMacOs.modifierRightShift | RawKeyEventDataMacOs.modifierShift;
    }
    if (pressed.contains(LogicalKeyboardKey.metaLeft)) {
      result |= RawKeyEventDataMacOs.modifierLeftCommand | RawKeyEventDataMacOs.modifierCommand;
    }
    if (pressed.contains(LogicalKeyboardKey.metaRight)) {
      result |= RawKeyEventDataMacOs.modifierRightCommand | RawKeyEventDataMacOs.modifierCommand;
    }
    if (pressed.contains(LogicalKeyboardKey.controlLeft)) {
      result |= RawKeyEventDataMacOs.modifierLeftControl | RawKeyEventDataMacOs.modifierControl;
    }
    if (pressed.contains(LogicalKeyboardKey.controlRight)) {
      result |= RawKeyEventDataMacOs.modifierRightControl | RawKeyEventDataMacOs.modifierControl;
    }
    if (pressed.contains(LogicalKeyboardKey.altLeft)) {
      result |= RawKeyEventDataMacOs.modifierLeftOption | RawKeyEventDataMacOs.modifierOption;
    }
    if (pressed.contains(LogicalKeyboardKey.altRight)) {
      result |= RawKeyEventDataMacOs.modifierRightOption | RawKeyEventDataMacOs.modifierOption;
    }
    final Set<LogicalKeyboardKey> functionKeys = <LogicalKeyboardKey>{
      LogicalKeyboardKey.f1,
      LogicalKeyboardKey.f2,
      LogicalKeyboardKey.f3,
      LogicalKeyboardKey.f4,
      LogicalKeyboardKey.f5,
      LogicalKeyboardKey.f6,
      LogicalKeyboardKey.f7,
      LogicalKeyboardKey.f8,
      LogicalKeyboardKey.f9,
      LogicalKeyboardKey.f10,
      LogicalKeyboardKey.f11,
      LogicalKeyboardKey.f12,
      LogicalKeyboardKey.f13,
      LogicalKeyboardKey.f14,
      LogicalKeyboardKey.f15,
      LogicalKeyboardKey.f16,
      LogicalKeyboardKey.f17,
      LogicalKeyboardKey.f18,
      LogicalKeyboardKey.f19,
      LogicalKeyboardKey.f20,
      LogicalKeyboardKey.f21,
    };
    if (pressed.intersection(functionKeys).isNotEmpty) {
      result |= RawKeyEventDataMacOs.modifierFunction;
    }
    if (pressed.intersection(kMacOsNumPadMap.values.toSet()).isNotEmpty) {
      result |= RawKeyEventDataMacOs.modifierNumericPad;
    }
    if (pressed.contains(LogicalKeyboardKey.capsLock)) {
      result |= RawKeyEventDataMacOs.modifierCapsLock;
    }
    return result;
  }

  /// Simulates sending a hardware key down event through the system channel.
  ///
  /// This only simulates key presses coming from a physical keyboard, not from a
  /// soft keyboard.
  ///
  /// Specify `platform` as one of the platforms allowed in
  /// [Platform.operatingSystem] to make the event appear to be from that type of
  /// system. Defaults to the operating system that the test is running on. Some
  /// platforms (e.g. Windows, iOS) are not yet supported.
  ///
  /// Keys that are down when the test completes are cleared after each test.
  ///
  /// See also:
  ///
  ///  - [simulateKeyUpEvent] to simulate the corresponding key up event.
  static Future<void> simulateKeyDownEvent(LogicalKeyboardKey key, {String platform}) async {
    return TestAsyncUtils.guard<void>(() async {
      platform ??= Platform.operatingSystem;
      assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');

      final Map<String, dynamic> data = getKeyData(key, platform: platform, isDown: true);
      await ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
        SystemChannels.keyEvent.name,
        SystemChannels.keyEvent.codec.encodeMessage(data),
            (ByteData data) {},
      );
    });
  }

  /// Simulates sending a hardware key up event through the system channel.
  ///
  /// This only simulates key presses coming from a physical keyboard, not from a
  /// soft keyboard.
  ///
  /// Specify `platform` as one of the platforms allowed in
  /// [Platform.operatingSystem] to make the event appear to be from that type of
  /// system. Defaults to the operating system that the test is running on. Some
  /// platforms (e.g. Windows, iOS) are not yet supported.
  ///
  /// See also:
  ///
  ///  - [simulateKeyDownEvent] to simulate the corresponding key down event.
  static Future<void> simulateKeyUpEvent(LogicalKeyboardKey key, {String platform}) async {
    return TestAsyncUtils.guard<void>(() async {
      platform ??= Platform.operatingSystem;
      assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');

      final Map<String, dynamic> data = getKeyData(key, platform: platform, isDown: false);
      await ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
        SystemChannels.keyEvent.name,
        SystemChannels.keyEvent.codec.encodeMessage(data),
            (ByteData data) {},
      );
    });
  }
}

/// Simulates sending a hardware key down event through the system channel.
///
/// This only simulates key presses coming from a physical keyboard, not from a
/// soft keyboard.
///
/// Specify `platform` as one of the platforms allowed in
/// [Platform.operatingSystem] to make the event appear to be from that type of
/// system. Defaults to the operating system that the test is running on. Some
/// platforms (e.g. Windows, iOS) are not yet supported.
///
/// Keys that are down when the test completes are cleared after each test.
///
/// See also:
///
///  - [simulateKeyUpEvent] to simulate the corresponding key up event.
Future<void> simulateKeyDownEvent(LogicalKeyboardKey key, {String platform}) {
  return KeyEventSimulator.simulateKeyDownEvent(key, platform: platform);
}

/// Simulates sending a hardware key up event through the system channel.
///
/// This only simulates key presses coming from a physical keyboard, not from a
/// soft keyboard.
///
/// Specify `platform` as one of the platforms allowed in
/// [Platform.operatingSystem] to make the event appear to be from that type of
/// system. Defaults to the operating system that the test is running on. Some
/// platforms (e.g. Windows, iOS) are not yet supported.
///
/// See also:
///
///  - [simulateKeyDownEvent] to simulate the corresponding key down event.
Future<void> simulateKeyUpEvent(LogicalKeyboardKey key, {String platform}) {
  return KeyEventSimulator.simulateKeyUpEvent(key, platform: platform);
}