// inspiration: https://github.com/andrepolischuk/keycomb

// TODO: write unit tests for keyBindings

// FIXME: implement an escape sequence for the separator +

import { IS_MAC } from './navigatorUtils.js'

/**
 * Get a named key from a key code.
 * For example:
 *     keyFromCode(65) returns 'A'
 *     keyFromCode(13) returns 'Enter'
 */
export function nameFromKeyCode(code: string): string {
  return codes[code] || ''
}

/**
 * Get the active key combination from a keyboard event.
 * For example returns "Ctrl+Shift+Up" or "Ctrl+A"
 * @param {KeyboardEvent} event
 * @return {string}
 */
export function keyComboFromEvent(event) {
  const combi = []

  if (event.ctrlKey) {
    combi.push('Ctrl')
  }
  if (event.metaKey) {
    combi.push('Command')
  }
  if (event.altKey) {
    combi.push(IS_MAC ? 'Option' : 'Alt')
  }
  if (event.shiftKey) {
    combi.push('Shift')
  }

  const keyName = nameFromKeyCode(event.which)
  if (!metaCodes[keyName]) {
    // prevent output like 'Ctrl+Ctrl'
    combi.push(keyName)
  }

  return combi.join('+')
}

/**
 * Create a function which can quickly find a keyBinding from a set of
 * keyBindings.
 * @param {Object.<String, String[]>} keyBindings
 * @return {function} Returns a findKeyBinding function
 */
export function createFindKeyBinding(keyBindings) {
  // turn the map with key bindings by name (multiple per binding) into a map by key combo
  const keyCombos = {}
  Object.keys(keyBindings).forEach((name) => {
    keyBindings[name].forEach((combo) => {
      keyCombos[normalizeKeyCombo(combo)] = name
    })
  })

  return function findKeyBinding(event) {
    const keyCombo = keyComboFromEvent(event)

    return keyCombos[normalizeKeyCombo(keyCombo)] || null
  }
}

/**
 * Normalize a key combo:
 *
 * - to upper case
 * - replace aliases like "?" with "/"
 *
 * @param {string} combo
 * @return {string}
 */
function normalizeKeyCombo(combo) {
  const upper = combo.toUpperCase()

  const last = upper[upper.length - 1]
  if (last in aliases) {
    return upper.substring(0, upper.length - 1) + aliases[last]
  }

  return upper
}

const metaCodes = {
  Ctrl: true,
  Command: true,
  Alt: true,
  Option: true,
  Shift: true
}

const codes = {
  8: 'Backspace',
  9: 'Tab',
  13: 'Enter',
  16: 'Shift',
  17: 'Ctrl',
  18: 'Alt',
  19: 'Pause_Break',
  20: 'Caps_Lock',
  27: 'Escape',
  33: 'Page_Up',
  34: 'Page_Down',
  35: 'End',
  36: 'Home',
  37: 'Left',
  38: 'Up',
  39: 'Right',
  40: 'Down',
  45: 'Insert',
  46: 'Delete',
  48: '0',
  49: '1',
  50: '2',
  51: '3',
  52: '4',
  53: '5',
  54: '6',
  55: '7',
  56: '8',
  57: '9',
  65: 'A',
  66: 'B',
  67: 'C',
  68: 'D',
  69: 'E',
  70: 'F',
  71: 'G',
  72: 'H',
  73: 'I',
  74: 'J',
  75: 'K',
  76: 'L',
  77: 'M',
  78: 'N',
  79: 'O',
  80: 'P',
  81: 'Q',
  82: 'R',
  83: 'S',
  84: 'T',
  85: 'U',
  86: 'V',
  87: 'W',
  88: 'X',
  89: 'Y',
  90: 'Z',
  91: 'Left_Window_Key',
  92: 'Right_Window_Key',
  93: 'Select_Key',
  96: 'Numpad_0',
  97: 'Numpad_1',
  98: 'Numpad_2',
  99: 'Numpad_3',
  100: 'Numpad_4',
  101: 'Numpad_5',
  102: 'Numpad_6',
  103: 'Numpad_7',
  104: 'Numpad_8',
  105: 'Numpad_9',
  106: 'Numpad_*',
  107: 'Numpad_+',
  109: 'Numpad_-',
  110: 'Numpad_.',
  111: 'Numpad_/',
  112: 'F1',
  113: 'F2',
  114: 'F3',
  115: 'F4',
  116: 'F5',
  117: 'F6',
  118: 'F7',
  119: 'F8',
  120: 'F9',
  121: 'F10',
  122: 'F11',
  123: 'F12',
  144: 'Num_Lock',
  145: 'Scroll_Lock',
  186: ';',
  187: '=',
  188: ',',
  189: '-',
  190: '.',
  191: '/',
  192: '`',
  219: '[',
  220: '\\',
  221: ']',
  222: "'"
}

// all secondary characters of the keyboard buttons (used via Shift)
const aliases = {
  '~': '`',
  '!': '1',
  '@': '2',
  '#': '3',
  $: '4',
  '%': '5',
  '^': '6',
  '&': '7',
  '*': '8',
  '(': '9',
  ')': '0',
  _: '-',
  '+': '=',
  '{': '[',
  '}': ']',
  '|': '\\',
  ':': ';',
  '"': '',
  '<': ',',
  '>': '.',
  '?': '/'
}