/**
 * 收藏夹管理 Composable
 * 提供收藏文件的添加、删除、排序等功能
 */

import { ref } from 'vue'
import { STORAGE_KEYS, DEFAULTS } from '@/utils/constants'
import { getPathSeparator } from '@/utils/fileUtils'
import { Message } from '@arco-design/web-vue'
import type { FavoriteFile, FileItem, DraggingState } from '@/types/file-system'

export function useFavorites() {
  // 收藏列表
  const favorites = ref<FavoriteFile[]>([])

  // 拖拽状态
  const draggingState = ref<DraggingState>({
    isDragging: false,
    draggedIndex: -1,
    pressedIndex: -1
  })

  /**
   * 排序收藏列表：置顶项在前（按 pinnedAt 降序），非置顶项按添加时间降序
   */
  const sortFavorites = () => {
    favorites.value = [...favorites.value].sort((a, b) => {
      // 置顶项优先
      if (a.pinnedAt && !b.pinnedAt) return -1
      if (!a.pinnedAt && b.pinnedAt) return 1
      // 都是置顶项，按置顶时间降序
      if (a.pinnedAt && b.pinnedAt) return b.pinnedAt - a.pinnedAt
      // 都不是置顶项，按添加时间降序（最新在前）
      return b.addedAt - a.addedAt
    })
  }

  /**
   * 从 localStorage 加载收藏列表
   */
  const loadFavorites = () => {
    try {
      const stored = localStorage.getItem(STORAGE_KEYS.FAVORITE_FILES)
      if (stored) {
        const loaded = JSON.parse(stored) as FavoriteFile[]

        // 数据迁移：将旧字段 is_dir 转换为 isDir
        favorites.value = loaded.map(fav => ({
          ...fav,
          isDir: fav.isDir ?? (fav as any).is_dir ?? false
        }))

        // 排序
        sortFavorites()
      }
    } catch (error) {
      console.error('加载收藏列表失败:', error)
    }
  }

  /**
   * 保存收藏列表到 localStorage
   */
  const saveFavorites = () => {
    try {
      localStorage.setItem(STORAGE_KEYS.FAVORITE_FILES, JSON.stringify(favorites.value))
    } catch (error) {
      console.error('保存收藏列表失败:', error)
    }
  }

  /**
   * 标准化路径用于比较（Windows 大小写不敏感）
   */
  const normalizePath = (path: string): string => {
    return path.toLowerCase()
  }

  /**
   * 添加收藏
   */
  const addFavorite = (file: FileItem) => {
    if (isFavorite(file.path)) {
      return false
    }

    if (favorites.value.length >= DEFAULTS.MAX_FAVORITES_LENGTH) {
      Message.warning(`收藏夹已满，最多收藏 ${DEFAULTS.MAX_FAVORITES_LENGTH} 项`)
      return false
    }

    favorites.value.push({
      ...file,
      addedAt: Date.now()
    } as FavoriteFile)
    sortFavorites()
    saveFavorites()
    return true
  }

  /**
   * 删除收藏
   */
  const removeFavorite = (path: string) => {
    const normalizedPath = normalizePath(path)
    const index = favorites.value.findIndex(fav => normalizePath(fav.path) === normalizedPath)
    if (index !== -1) {
      favorites.value.splice(index, 1)
      saveFavorites()
    }
  }

  /**
   * 切换收藏状态
   */
  const toggleFavorite = (file: FileItem) => {
    if (isFavorite(file.path)) {
      removeFavorite(file.path)
      return false
    }
    addFavorite(file)
    return true
  }

  /**
   * 检查是否已收藏
   */
  const isFavorite = (path: string): boolean => {
    const normalizedPath = normalizePath(path)
    return favorites.value.some(fav => normalizePath(fav.path) === normalizedPath)
  }

  /**
   * 切换置顶状态
   */
  const togglePin = (path: string) => {
    const normalizedPath = normalizePath(path)
    const fav = favorites.value.find(f => normalizePath(f.path) === normalizedPath)
    if (fav) {
      fav.pinnedAt = fav.pinnedAt ? undefined : Date.now()
      sortFavorites()
      saveFavorites()
    }
  }

  /**
   * 检查是否已置顶
   */
  const isPinned = (path: string): boolean => {
    const normalizedPath = normalizePath(path)
    const fav = favorites.value.find(f => normalizePath(f.path) === normalizedPath)
    return !!fav?.pinnedAt
  }

  /**
   * 更新收藏项路径（重命名时使用，保留置顶状态和添加时间）
   */
  const updateFavoritePath = (oldPath: string, newName: string) => {
    const normalizedOld = normalizePath(oldPath)
    const fav = favorites.value.find(f => normalizePath(f.path) === normalizedOld)
    if (!fav) return

    const separator = getPathSeparator(oldPath)
    const parentPath = oldPath.substring(
      0,
      Math.max(oldPath.lastIndexOf('\\'), oldPath.lastIndexOf('/'))
    )
    fav.path = parentPath + separator + newName
    fav.name = newName
    saveFavorites()
  }

  // 拖拽方法
  const onLongPressStart = (event: MouseEvent | TouchEvent, index: number) => {
    if (event instanceof MouseEvent && event.button !== 0) return
    if (!(event instanceof MouseEvent) && !(event instanceof TouchEvent)) return

    draggingState.value.pressedIndex = index
    draggingState.value.draggedIndex = index
  }

  const onLongPressCancel = () => {
    if (!draggingState.value.isDragging) {
      draggingState.value.pressedIndex = -1
      draggingState.value.draggedIndex = -1
    }
  }

  const onDragStart = (event: DragEvent, index: number) => {
    draggingState.value.isDragging = true
    draggingState.value.draggedIndex = index
    if (event.dataTransfer) {
      event.dataTransfer.effectAllowed = 'move'
      event.dataTransfer.setData('text/plain', index.toString())
    }
  }

  const onDragOver = (event: DragEvent) => {
    event.preventDefault()
    if (event.dataTransfer) {
      event.dataTransfer.dropEffect = 'move'
    }
  }

  const onDrop = (event: DragEvent, targetIndex: number) => {
    event.preventDefault()

    const fromIndex = draggingState.value.draggedIndex
    if (fromIndex === targetIndex || fromIndex === -1) {
      resetDragging()
      return
    }

    const item = favorites.value.splice(fromIndex, 1)[0]
    favorites.value.splice(targetIndex, 0, item)
    saveFavorites()
    resetDragging()
  }

  const onDragEnd = () => {
    resetDragging()
  }

  const resetDragging = () => {
    draggingState.value.isDragging = false
    draggingState.value.draggedIndex = -1
    draggingState.value.pressedIndex = -1
  }

  // 组件挂载时加载收藏列表
  loadFavorites()

  return {
    favorites,
    draggingState,

    addFavorite,
    removeFavorite,
    toggleFavorite,
    isFavorite,
    togglePin,
    isPinned,
    updateFavoritePath,

    onLongPressStart,
    onLongPressCancel,
    onDragStart,
    onDragOver,
    onDrop,
    onDragEnd,

    loadFavorites,
    saveFavorites,
    resetDragging
  }
}