// Adapted from T3 Code's libghostty-vt browser adapter (MIT, T3 Tools Inc.).
// See LICENSE-T3CODE in this directory.

// This order mirrors GhosttyKey in ghostty/vt/key/event.h. The values are
// intentionally derived from the official W3C-aligned enum instead of
// maintaining a second keyboard protocol.
const ghosttyKeyboardCodes = [
  'Unidentified',
  'Backquote',
  'Backslash',
  'BracketLeft',
  'BracketRight',
  'Comma',
  'Digit0',
  'Digit1',
  'Digit2',
  'Digit3',
  'Digit4',
  'Digit5',
  'Digit6',
  'Digit7',
  'Digit8',
  'Digit9',
  'Equal',
  'IntlBackslash',
  'IntlRo',
  'IntlYen',
  'KeyA',
  'KeyB',
  'KeyC',
  'KeyD',
  'KeyE',
  'KeyF',
  'KeyG',
  'KeyH',
  'KeyI',
  'KeyJ',
  'KeyK',
  'KeyL',
  'KeyM',
  'KeyN',
  'KeyO',
  'KeyP',
  'KeyQ',
  'KeyR',
  'KeyS',
  'KeyT',
  'KeyU',
  'KeyV',
  'KeyW',
  'KeyX',
  'KeyY',
  'KeyZ',
  'Minus',
  'Period',
  'Quote',
  'Semicolon',
  'Slash',
  'AltLeft',
  'AltRight',
  'Backspace',
  'CapsLock',
  'ContextMenu',
  'ControlLeft',
  'ControlRight',
  'Enter',
  'MetaLeft',
  'MetaRight',
  'ShiftLeft',
  'ShiftRight',
  'Space',
  'Tab',
  'Convert',
  'KanaMode',
  'NonConvert',
  'Delete',
  'End',
  'Help',
  'Home',
  'Insert',
  'PageDown',
  'PageUp',
  'ArrowDown',
  'ArrowLeft',
  'ArrowRight',
  'ArrowUp',
  'NumLock',
  'Numpad0',
  'Numpad1',
  'Numpad2',
  'Numpad3',
  'Numpad4',
  'Numpad5',
  'Numpad6',
  'Numpad7',
  'Numpad8',
  'Numpad9',
  'NumpadAdd',
  'NumpadBackspace',
  'NumpadClear',
  'NumpadClearEntry',
  'NumpadComma',
  'NumpadDecimal',
  'NumpadDivide',
  'NumpadEnter',
  'NumpadEqual',
  'NumpadMemoryAdd',
  'NumpadMemoryClear',
  'NumpadMemoryRecall',
  'NumpadMemoryStore',
  'NumpadMemorySubtract',
  'NumpadMultiply',
  'NumpadParenLeft',
  'NumpadParenRight',
  'NumpadSubtract',
  'NumpadSeparator',
  'NumpadArrowUp',
  'NumpadArrowDown',
  'NumpadArrowRight',
  'NumpadArrowLeft',
  'NumpadBegin',
  'NumpadHome',
  'NumpadEnd',
  'NumpadInsert',
  'NumpadDelete',
  'NumpadPageUp',
  'NumpadPageDown',
  'Escape',
  'F1',
  'F2',
  'F3',
  'F4',
  'F5',
  'F6',
  'F7',
  'F8',
  'F9',
  'F10',
  'F11',
  'F12',
  'F13',
  'F14',
  'F15',
  'F16',
  'F17',
  'F18',
  'F19',
  'F20',
  'F21',
  'F22',
  'F23',
  'F24',
  'F25',
  'Fn',
  'FnLock',
  'PrintScreen',
  'ScrollLock',
  'Pause',
  'BrowserBack',
  'BrowserFavorites',
  'BrowserForward',
  'BrowserHome',
  'BrowserRefresh',
  'BrowserSearch',
  'BrowserStop',
  'Eject',
  'LaunchApp1',
  'LaunchApp2',
  'LaunchMail',
  'MediaPlayPause',
  'MediaSelect',
  'MediaStop',
  'MediaTrackNext',
  'MediaTrackPrevious',
  'Power',
  'Sleep',
  'AudioVolumeDown',
  'AudioVolumeMute',
  'AudioVolumeUp',
  'WakeUp',
  'Copy',
  'Cut',
  'Paste',
] as const;

const codeToGhosttyKey = new Map<string, number>(
  ghosttyKeyboardCodes.map((code, index) => [code, index]),
);

export function ghosttyKeyForCode(code: string): number {
  return codeToGhosttyKey.get(code) ?? 0;
}

export interface GhosttyKeyboardLayoutMap {
  get(code: string): string | undefined;
}

const shiftedToUnshiftedCharacter = new Map<string, string>([
  ['!', '1'],
  ['@', '2'],
  ['#', '3'],
  ['$', '4'],
  ['%', '5'],
  ['^', '6'],
  ['&', '7'],
  ['*', '8'],
  ['(', '9'],
  [')', '0'],
  ['~', '`'],
  ['_', '-'],
  ['+', '='],
  ['{', '['],
  ['}', ']'],
  ['|', '\\'],
  [':', ';'],
  ['"', "'"],
  ['<', ','],
  ['>', '.'],
  ['?', '/'],
]);

let keyboardLayoutMapPromise: Promise<GhosttyKeyboardLayoutMap | undefined> | undefined;

export function loadGhosttyKeyboardLayoutMap(): Promise<GhosttyKeyboardLayoutMap | undefined> {
  if (keyboardLayoutMapPromise) return keyboardLayoutMapPromise;
  // SAFETY: navigator.keyboard is Chromium-only and absent from lib.dom; the
  // optional field keeps every other engine on the undefined branch.
  const keyboard = (
    globalThis.navigator as Navigator & {
      readonly keyboard?: { getLayoutMap(): Promise<GhosttyKeyboardLayoutMap> };
    } | undefined
  )?.keyboard;
  const promise = keyboard?.getLayoutMap().catch(() => undefined) ?? Promise.resolve(undefined);
  keyboardLayoutMapPromise = promise;
  return promise;
}

// Browsers do not expose consumed modifiers; treat Shift as consumed for
// unchorded character input.
export function ghosttyConsumedMods(
  event: Pick<KeyboardEvent, 'altKey' | 'ctrlKey' | 'key' | 'metaKey' | 'shiftKey'>,
): number {
  if (!event.shiftKey || event.ctrlKey || event.altKey || event.metaKey) return 0;
  return [...event.key].length === 1 ? 1 : 0;
}

export function ghosttyUnshiftedCodepoint(
  event: Pick<KeyboardEvent, 'code' | 'key' | 'shiftKey'>,
  layoutMap?: GhosttyKeyboardLayoutMap,
): number {
  if ([...event.key].length !== 1) return 0;
  const layoutCharacter = layoutMap?.get(event.code);
  if (layoutCharacter && [...layoutCharacter].length === 1) {
    return layoutCharacter.codePointAt(0) ?? 0;
  }
  if (/^[A-Z]$/u.test(event.key)) return event.key.charCodeAt(0) + 32;
  if (event.shiftKey) {
    const unshiftedCharacter = shiftedToUnshiftedCharacter.get(event.key);
    if (unshiftedCharacter) return unshiftedCharacter.codePointAt(0) ?? 0;
    const lowercase = event.key.toLowerCase();
    if (lowercase !== event.key && [...lowercase].length === 1) {
      return lowercase.codePointAt(0) ?? 0;
    }
    // Without layout data the unshifted form of a shifted key is unknowable;
    // reporting the shifted character as unshifted corrupts Kitty alternate keys.
    return 0;
  }
  return event.key.codePointAt(0) ?? 0;
}