import {createContext, useContext, useEffect, useMemo, useRef} from 'react'
import EmojiPicker from '@emoji-mart/react'
import {DropdownMenu} from 'radix-ui'

import {useA11y} from '#/state/a11y'
import {textInputWebEmitter} from '#/view/com/composer/text-input/textInputWebEmitter'
import {atoms as a, flatten} from '#/alf'
import * as Menu from '../Menu'
import {useWebPreloadEmoji} from './preload'
import {
  type Emoji,
  type PickerProps,
  type RootProps,
  type TriggerProps,
} from './types'

export * from './types'

const EmojiPickerContext = createContext<{
  onEmojiSelect: (emoji: Emoji) => void
  nextFocusRef: RootProps['nextFocusRef']
} | null>(null)

/**
 * Provides emoji picker context and wraps children in a {@link Menu.Root}.
 *
 * On emoji select, fires a `textInputWebEmitter` event (for web text inputs
 * that listen for emoji insertions) and forwards to the optional
 * `onEmojiSelect` callback.
 *
 * @platform web
 */
export function Root({
  children,
  control,
  onEmojiSelect,
  preloadOnMount = true,
  nextFocusRef,
}: RootProps) {
  useWebPreloadEmoji({immediate: preloadOnMount})

  const value = useMemo(
    () => ({
      onEmojiSelect: (emoji: Emoji) => {
        textInputWebEmitter.emit('emoji-inserted', emoji)

        if (onEmojiSelect) onEmojiSelect(emoji)
      },
      nextFocusRef,
    }),
    [onEmojiSelect, nextFocusRef],
  )

  return (
    <EmojiPickerContext value={value}>
      <Menu.Root control={control}>{children}</Menu.Root>
    </EmojiPickerContext>
  )
}

/**
 * Passthrough to {@link Menu.Trigger}. Accepts the same render-prop children
 * pattern.
 *
 * @platform web
 */
export function Trigger(props: TriggerProps) {
  return <Menu.Trigger {...props} />
}

/**
 * Renders the emoji picker inside a Radix `DropdownMenu.Portal`.
 *
 * Holding Shift while selecting an emoji keeps the picker open for
 * multi-select. Otherwise the menu closes after each selection.
 *
 * Must be rendered inside a {@link Root}.
 *
 * @platform web
 */
export function Picker({keepOpenWhenShiftHeld = true}: PickerProps) {
  const {onEmojiSelect, nextFocusRef} = useEmojiPickerContext()
  const {control} = Menu.useMenuContext()
  const {reduceMotionEnabled} = useA11y()
  const isShiftDown = useRef(false)

  useEffect(() => {
    const onKeyDown = (e: KeyboardEvent) => {
      if (e.key === 'Shift') {
        isShiftDown.current = true
      }
    }
    const onKeyUp = (e: KeyboardEvent) => {
      if (e.key === 'Shift') {
        isShiftDown.current = false
      }
    }
    window.addEventListener('keydown', onKeyDown, true)
    window.addEventListener('keyup', onKeyUp, true)

    return () => {
      window.removeEventListener('keydown', onKeyDown, true)
      window.removeEventListener('keyup', onKeyUp, true)
    }
  }, [])

  return (
    <DropdownMenu.Portal>
      <DropdownMenu.Content
        sideOffset={5}
        collisionPadding={{left: 5, right: 5, bottom: 5}}
        className="dropdown-menu-transform-origin dropdown-menu-constrain-size"
        onCloseAutoFocus={evt => {
          if (!nextFocusRef) return
          let element =
            nextFocusRef instanceof Function
              ? nextFocusRef()
              : nextFocusRef.current
          if (element) {
            evt.preventDefault()
            element.focus()
          }
        }}>
        <div
          onWheel={evt => evt.stopPropagation()}
          style={flatten([!reduceMotionEnabled && a.zoom_fade_in])}>
          <EmojiPicker
            autoFocus
            onEmojiSelect={(emoji: Emoji) => {
              onEmojiSelect(emoji)

              if (!keepOpenWhenShiftHeld || !isShiftDown.current) {
                control.close()
              }
            }}
          />
        </div>
      </DropdownMenu.Content>
    </DropdownMenu.Portal>
  )
}

function useEmojiPickerContext() {
  const ctx = useContext(EmojiPickerContext)
  if (!ctx)
    throw new Error(
      'EmojiPicker.Picker must be used within an EmojiPicker.Root component',
    )
  return ctx
}