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

import { ref, watch } from 'vue'
import { STORAGE_KEYS } from '@/utils/constants'
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
  })

  /**
   * 从 localStorage 加载收藏列表
   */
  const loadFavorites = () => {
    try {
      const stored = localStorage.getItem(STORAGE_KEYS.FAVORITE_FILES)
      if (stored) {
        favorites.value = JSON.parse(stored)
      }
    } 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)
    }
  }

  /**
   * 添加收藏
   */
  const addFavorite = (file: FileItem) => {
    // 检查是否已存在
    const exists = favorites.value.some(fav => fav.path === file.path)
    if (exists) {
      return false
    }

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

  /**
   * 标准化路径用于比较（处理正斜杠/反斜杠不一致）
   */
  const normalizePath = (path: string): string => {
    return path.replace(/\\/g, '/').toLowerCase()
  }

  /**
   * 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) => {
    const exists = isFavorite(file.path)
    if (exists) {
      removeFavorite(file.path)
      return false
    } else {
      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)
  }

  /**
   * 长按开始
   */
  const onLongPressStart = (event: MouseEvent | TouchEvent, index: number) => {
    const isMouse = event instanceof MouseEvent
    const isTouch = event instanceof TouchEvent

    // 只支持鼠标左键或触摸
    if (isMouse && event.button !== 0) return
    if (!isMouse && !isTouch) return

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

  /**
   * 长按取消
   */
  const onLongPressCancel = () => {
    if (!draggingState.value.isDragging) {
      draggingState.value.pressedIndex = -1
      draggingState.value.draggedIndex = -1
    }
  }

  /**
   * 拖拽开始
   */
  const onDragStart = (event: DragEvent, index: number) => {
    draggingState.value.isDragging = true
    draggingState.value.draggedIndex = index

    // 设置拖拽数据
    if (event.dataTransfer) {
      event.dataTransfer.effectAllowed = 'move'
      event.dataTransfer.setData('text/plain', index.toString())
    }
  }

  /**
   * 拖拽经过
   */
  const onDragOver = (event: DragEvent) => {
    event.preventDefault()
    if (event.dataTransfer) {
      event.dataTransfer.dropEffect = 'move'
    }
  }

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

    const fromIndex = draggingState.value.draggedIndex
    const toIndex = targetIndex

    if (fromIndex === toIndex || fromIndex === -1) {
      resetDragging()
      return
    }

    // 移动元素
    const item = favorites.value.splice(fromIndex, 1)[0]
    favorites.value.splice(toIndex, 0, item)
    saveFavorites()

    resetDragging()
  }

  /**
   * 拖拽结束
   */
  const onDragEnd = () => {
    resetDragging()
  }

  /**
   * 重置拖拽状态
   */
  const resetDragging = () => {
    draggingState.value.isDragging = false
    draggingState.value.draggedIndex = -1
    draggingState.value.pressedIndex = -1
  }

  /**
   * 重新排序
   */
  const reorder = (fromIndex: number, toIndex: number) => {
    if (fromIndex === toIndex) return

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

  // 组件挂载时加载收藏列表
  loadFavorites()

  return {
    // 状态
    favorites,
    draggingState,

    // 方法
    addFavorite,
    removeFavorite,
    toggleFavorite,
    isFavorite,

    // 拖拽方法
    onLongPressStart,
    onLongPressCancel,
    onDragStart,
    onDragOver,
    onDrop,
    onDragEnd,
    reorder,

    // 工具方法
    loadFavorites,
    saveFavorites,
    resetDragging
  }
}