const specialKeyMap = {
  backspace: 8,
  tab: 9,
  enter: 13,
  shift: 16,
  ctrl: 17,
  alt: 18,
  pausebreak: 19,
  capslock: 20,
  escape: 27,
  pgup: 33,
  pgdown: 34,
  end: 35,
  home: 36,
  left: 37,
  up: 38,
  right: 39,
  down: 40,
  insert: 45,
  delete: 46,
  'left-window': 91,
  'right-window': 92,
  select: 93,
  numpad0: 96,
  numpad1: 97,
  numpad2: 98,
  numpad3: 99,
  numpad4: 100,
  numpad5: 101,
  numpad6: 102,
  numpad7: 103,
  numpad8: 104,
  numpad9: 105,
  multiply: 106,
  add: 107,
  subtract: 109,
  decimal: 110,
  divide: 111,
  f1: 112,
  f2: 113,
  f3: 114,
  f4: 115,
  f5: 116,
  f6: 117,
  f7: 118,
  f8: 119,
  f9: 120,
  f10: 121,
  f11: 122,
  f12: 123,
  numlock: 144,
  scrolllock: 145,
  'semi-colon': 186,
  equals: 187,
  comma: 188,
  dash: 189,
  period: 190,
  fwdslash: 191,
  grave: 192,
  'open-bracket': 219,
  bkslash: 220,
  'close-braket': 221,
  'single-quote': 222
}

class Input {
  constructor (canvas) {
    this.keyList = {}
    this.previousKeyList = {}
    this.canvas = canvas

    this.mouse = {
      pos: { x: 0, y: 0 },
      frame: { x: 0, y: 0 },
      previous: { x: 0, y: 0 }
    }

    window.addEventListener('keydown', (e) => this.keyDown(e), false)
    window.addEventListener('keyup', (e) => this.keyUp(e), false)

    canvas.addEventListener('mousemove', (e) => {
      let x
      let y

      if (e.changedTouches) {
        const touch = e.changedTouches[0]
        if (touch) {
          e.pageX = touch.pageX
          e.pageY = touch.pageY
        }
      }

      if (e.pageX || e.pageY) {
        x = e.pageX
        y = e.pageY
      } else {
        x = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft
        y = e.clientY + document.body.scrollTop + document.documentElement.scrollTop
      }

      x -= canvas.offsetLeft
      y -= canvas.offsetTop

      this.mouse.frame.x = x
      this.mouse.frame.y = y
    }, false)

    canvas.addEventListener('mousedown', (e) => {
      e.preventDefault()
      this.mouse['btn' + e.button] = true
    })

    canvas.addEventListener('mouseup', (e) => {
      e.preventDefault()
      this.mouse['btn' + e.button] = false
    })

    canvas.addEventListener('contextmenu', (e) => {
      e.preventDefault()
    })
  }

  get mousePos () {
    return this.mouse.pos
  }

  get mouseMoved () {
    return (this.mouse.pos.x !== this.mouse.previous.x ||
      this.mouse.pos.y !== this.mouse.previous.y)
  }

  get mouseOffset () {
    return {
      x: this.mouse.previous.x - this.mouse.pos.x,
      y: this.mouse.previous.y - this.mouse.pos.y
    }
  }

  toggleKey (keyCode, on) {
    // Find key in special key list
    let key = null
    for (const k in specialKeyMap) {
      const val = specialKeyMap[k]
      if (keyCode === val) {
        key = k
        break
      }
    }

    // Use fromCharCode
    if (!key) {
      key = String.fromCharCode(keyCode).toLowerCase()
    }

    this.keyList[key] = (on === true)
  }

  keyDown (e) {
    let keycode

    if (window.event) {
      keycode = window.event.keyCode
    } else if (e) {
      keycode = e.which
    }

    this.toggleKey(keycode, true)
  }

  keyUp (e) {
    let keycode

    if (window.event) {
      keycode = window.event.keyCode
    } else if (e) {
      keycode = e.which
    }

    this.toggleKey(keycode, false)
  }

  down (key) {
    return this.keyList[key] != null ? this.keyList[key] : false
  }

  downLast (key) {
    return this.previousKeyList[key] != null ? this.previousKeyList[key] : false
  }

  isDown (key) {
    return this.down(key) && this.downLast(key)
  }

  isUp (key) {
    return !this.isDown(key)
  }

  isPressed (key) {
    return this.down(key) === true && this.downLast(key) === false
  }

  update () {
    this.previousKeyList = {}
    for (const k in this.keyList) {
      if (this.keyList[k] === true) {
        this.previousKeyList[k] = true
      }
    }

    // Mouse positions in the previous frame
    this.mouse.previous.x = this.mouse.pos.x
    this.mouse.previous.y = this.mouse.pos.y

    // Mouse positions in the current frame
    // Convert to OpenGL coordinate system
    this.mouse.pos.x = this.mouse.frame.x / this.canvas.width * 2 - 1
    this.mouse.pos.y = this.mouse.frame.y / this.canvas.height * 2 - 1
  }
}

export default Input