import { onBeforeUnmount, onMounted } from "@nuxtjs/composition-api"
import { HoppAction, invokeAction } from "./actions"
import { isAppleDevice } from "./platformutils"

/**
 * This variable keeps track whether keybindings are being accepted
 * true -> Keybindings are checked
 * false -> Key presses are ignored (Keybindings are not checked)
 */
let keybindingsEnabled = true

/**
 * Alt is also regarded as macOS OPTION (⌥) key
 * Ctrl is also regarded as macOS COMMAND (⌘) key (NOTE: this differs from HTML Keyboard spec where COMMAND is Meta key!)
 */
type ModifierKeys = "ctrl" | "alt"

/* eslint-disable prettier/prettier */
type Key = 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'g' | 'h' | 'i' | 'j' | 'k'
| 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's' | 't' | 'u' | 'v' | 'w' | 'x' 
| 'y' | 'z' | '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
| "up" | "down" | "left" | "right"
/* eslint-enable */

type ShortcutKey = `${ModifierKeys}-${Key}`

export const bindings: {
  // eslint-disable-next-line no-unused-vars
  [_ in ShortcutKey]?: HoppAction
} = {
  "ctrl-g": "request.send-cancel",
  "ctrl-i": "request.reset",
  "ctrl-k": "request.copy-link",
  "ctrl-s": "request.save",
  "alt-up": "request.method.next",
  "alt-down": "request.method.prev",
  "alt-g": "request.method.get",
  "alt-h": "request.method.head",
  "alt-p": "request.method.post",
  "alt-u": "request.method.put",
  "alt-x": "request.method.delete",
}

/**
 * A composable that hooks to the caller component's
 * lifecycle and hooks to the keyboard events to fire
 * the appropriate actions based on keybindings
 */
export function hookKeybindingsListener() {
  onMounted(() => {
    document.addEventListener("keydown", handleKeyDown)
  })

  onBeforeUnmount(() => {
    document.removeEventListener("keydown", handleKeyDown)
  })
}

function handleKeyDown(ev: KeyboardEvent) {
  // Do not check keybinds if the mode is disabled
  if (!keybindingsEnabled) return

  const binding = generateKeybindingString(ev)
  if (!binding) return

  const boundAction = bindings[binding]
  if (!boundAction) return

  ev.preventDefault()
  invokeAction(boundAction)
}

function generateKeybindingString(ev: KeyboardEvent): ShortcutKey | null {
  // All our keybinds need to have one modifier pressed atleast
  const modifierKey = getActiveModifier(ev)
  if (!modifierKey) return null

  const key = getPressedKey(ev)
  if (!key) return null

  return `${modifierKey}-${key}` as ShortcutKey
}

function getPressedKey(ev: KeyboardEvent): Key | null {
  const val = ev.key.toLowerCase()

  // Check arrow keys
  if (val === "arrowup") return "up"
  else if (val === "arrowdown") return "down"
  else if (val === "arrowleft") return "left"
  else if (val === "arrowright") return "right"

  // Check letter keys
  if (val.length === 1 && val.toUpperCase() !== val.toLowerCase())
    return val as Key

  // Check if number keys
  if (val.length === 1 && !isNaN(val as any)) return val as Key

  // If no other cases match, this is not a valid key
  return null
}

function getActiveModifier(ev: KeyboardEvent): ModifierKeys | null {
  // Just ignore everything if Shift is pressed (for now)
  if (ev.shiftKey) return null

  // We only allow one modifier key to be pressed (for now)
  // Control key (+ Command) gets priority and if Alt is also pressed, it is ignored
  if (isAppleDevice() && ev.metaKey) return "ctrl"
  else if (!isAppleDevice() && ev.ctrlKey) return "ctrl"

  // Test for Alt key
  if (ev.altKey) return "alt"

  return null
}

/**
 * This composable allows for the UI component to be disabled if the component in question is mounted
 */
export function useKeybindingDisabler() {
  // TODO: Move to a lock based system that keeps the bindings disabled until all locks are lifted
  const disableKeybindings = () => {
    keybindingsEnabled = false
    console.log("Keybinds disabled by a component")
  }

  const enableKeybindings = () => {
    keybindingsEnabled = true
    console.log("Keybinds enabled by a component")
  }

  return {
    disableKeybindings,
    enableKeybindings,
  }
}