import { computed, type CSSProperties, ref } from 'vue'

import { onUnload } from '@dcloudio/uni-app'

type KeyboardHeightChangeResult = {
  height?: number
}

type KeyboardHeightChangeCallback = (result: KeyboardHeightChangeResult) => void

type MiniProgramKeyboardApi = {
  onKeyboardHeightChange?: (callback: KeyboardHeightChangeCallback) => void
  offKeyboardHeightChange?: (callback: KeyboardHeightChangeCallback) => void
}

type MiniProgramWindowInfo = UniApp.GetWindowInfoResult & {
  safeAreaInsets?: {
    bottom?: number
  }
  safeArea?: {
    bottom?: number
  }
}

const FOOTER_TOP_PADDING_RPX = 20
const FOOTER_BOTTOM_PADDING_RPX = 20
const FOOTER_BUTTON_HEIGHT_RPX = 88
const CONTENT_EXTRA_BOTTOM_RPX = 24

export const useTaskFormSafeArea = () => {
  const keyboardApi = uni as unknown as MiniProgramKeyboardApi

  const windowWidth = ref(375)
  const safeAreaBottom = ref(0)
  const keyboardHeight = ref(0)
  let keyboardListenerRegistered = false

  const rpxToPx = (rpx: number) => {
    return (windowWidth.value / 750) * rpx
  }

  const activeSafeAreaBottom = computed(() => {
    return keyboardHeight.value > 0 ? 0 : safeAreaBottom.value
  })

  const keyboardVisible = computed(() => keyboardHeight.value > 0)

  const footerHeightPx = computed(() => {
    return (
      rpxToPx(FOOTER_TOP_PADDING_RPX + FOOTER_BUTTON_HEIGHT_RPX + FOOTER_BOTTOM_PADDING_RPX) +
      activeSafeAreaBottom.value
    )
  })

  const contentStyle = computed<CSSProperties>(() => {
    const paddingBottom =
      footerHeightPx.value + keyboardHeight.value + rpxToPx(CONTENT_EXTRA_BOTTOM_RPX)

    return {
      paddingBottom: `${paddingBottom}px`,
    }
  })

  const footerStyle = computed<CSSProperties>(() => {
    return {
      bottom: `${keyboardHeight.value}px`,
      paddingBottom: `${rpxToPx(FOOTER_BOTTOM_PADDING_RPX) + activeSafeAreaBottom.value}px`,
    }
  })

  const initSystemLayout = () => {
    const windowInfo = uni.getWindowInfo() as MiniProgramWindowInfo

    windowWidth.value = windowInfo.windowWidth || 375

    if (typeof windowInfo.safeAreaInsets?.bottom === 'number') {
      safeAreaBottom.value = windowInfo.safeAreaInsets.bottom
      return
    }

    if (
      typeof windowInfo.safeArea?.bottom === 'number' &&
      typeof windowInfo.screenHeight === 'number'
    ) {
      safeAreaBottom.value = Math.max(windowInfo.screenHeight - windowInfo.safeArea.bottom, 0)
      return
    }

    safeAreaBottom.value = 0
  }

  const handleKeyboardHeightChange: KeyboardHeightChangeCallback = (result) => {
    const height = Number(result.height ?? 0)

    keyboardHeight.value = Number.isFinite(height) && height > 0 ? height : 0
  }

  const initSafeArea = () => {
    initSystemLayout()

    if (
      keyboardListenerRegistered ||
      !keyboardApi.onKeyboardHeightChange ||
      !keyboardApi.offKeyboardHeightChange
    ) {
      return
    }

    keyboardApi.onKeyboardHeightChange(handleKeyboardHeightChange)
    keyboardListenerRegistered = true
  }

  const disposeSafeArea = () => {
    if (!keyboardListenerRegistered) {
      return
    }

    keyboardApi.offKeyboardHeightChange?.(handleKeyboardHeightChange)
    keyboardListenerRegistered = false
    keyboardHeight.value = 0
  }

  onUnload(disposeSafeArea)

  return {
    contentStyle,
    footerStyle,
    keyboardVisible,
    initSafeArea,
  }
}