import { defineStore } from 'pinia'
import { ref, computed } from 'vue'

export interface OfflineAction {
  id: string
  type: 'create' | 'update' | 'delete'
  entity: 'transaction' | 'category' | 'account'
  data: any
  timestamp: string
  retryCount: number
  maxRetries: number
  error?: string
}

export const useOfflineStore = defineStore('offline', () => {
  // 网络状态
  const isOnline = ref(navigator.onLine)
  const connectionType = ref<string>('unknown')
  const lastOnlineTime = ref<Date | null>(null)
  const lastOfflineTime = ref<Date | null>(null)

  // 离线操作队列
  const pendingActions = ref<OfflineAction[]>([])
  const failedActions = ref<OfflineAction[]>([])

  // 同步状态
  const isSyncing = ref(false)
  const syncProgress = ref(0)
  const syncError = ref<string | null>(null)
  const lastSyncTime = ref<Date | null>(null)

  // 离线提示
  const showOfflineIndicator = ref(false)
  const offlineMessage = ref('')

  // 计算属性
  const hasConnection = computed(() => isOnline.value)
  const hasPendingActions = computed(() => pendingActions.value.length > 0)
  const hasFailedActions = computed(() => failedActions.value.length > 0)
  const totalPendingCount = computed(() => pendingActions.value.length + failedActions.value.length)

  const connectionStatus = computed(() => {
    if (isOnline.value) {
      return {
        status: 'online',
        message: '已连接',
        color: 'green'
      }
    } else {
      return {
        status: 'offline',
        message: '离线模式',
        color: 'orange'
      }
    }
  })

  // 网络状态监听
  function setupNetworkListeners() {
    // 监听网络状态变化
    window.addEventListener('online', handleOnline)
    window.addEventListener('offline', handleOffline)

    // 检测连接类型（如果支持）
    if ('connection' in navigator) {
      const connection = (navigator as any).connection
      connectionType.value = connection.effectiveType || 'unknown'
      
      connection.addEventListener('change', () => {
        connectionType.value = connection.effectiveType || 'unknown'
      })
    }

    // 初始状态
    updateNetworkStatus()
  }

  // 处理上线事件
  function handleOnline() {
    isOnline.value = true
    lastOnlineTime.value = new Date()
    showOfflineIndicator.value = false
    
    console.log('网络已连接，开始同步离线数据')
    
    // 自动同步离线操作
    if (hasPendingActions.value || hasFailedActions.value) {
      syncOfflineActions()
    }
  }

  // 处理离线事件
  function handleOffline() {
    isOnline.value = false
    lastOfflineTime.value = new Date()
    showOfflineIndicator.value = true
    offlineMessage.value = '当前处于离线模式，数据将在网络恢复后自动同步'
    
    console.log('网络已断开，进入离线模式')
  }

  // 更新网络状态
  function updateNetworkStatus() {
    const wasOnline = isOnline.value
    isOnline.value = navigator.onLine
    
    if (wasOnline !== isOnline.value) {
      if (isOnline.value) {
        handleOnline()
      } else {
        handleOffline()
      }
    }
  }

  // 添加离线操作到队列
  function addOfflineAction(action: Omit<OfflineAction, 'id' | 'timestamp' | 'retryCount'>) {
    const offlineAction: OfflineAction = {
      ...action,
      id: generateActionId(),
      timestamp: new Date().toISOString(),
      retryCount: 0
    }

    pendingActions.value.push(offlineAction)
    console.log('添加离线操作到队列:', offlineAction)
  }

  // 生成操作ID
  function generateActionId(): string {
    return `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`
  }

  // 同步离线操作
  async function syncOfflineActions() {
    if (isSyncing.value || !isOnline.value) return

    isSyncing.value = true
    syncProgress.value = 0
    syncError.value = null

    try {
      const allActions = [...pendingActions.value, ...failedActions.value]
      const totalActions = allActions.length

      if (totalActions === 0) {
        isSyncing.value = false
        return
      }

      console.log(`开始同步 ${totalActions} 个离线操作`)

      for (let i = 0; i < allActions.length; i++) {
        const action = allActions[i]
        
        try {
          await executeOfflineAction(action)
          
          // 从队列中移除成功的操作
          removeActionFromQueues(action.id)
          
          syncProgress.value = ((i + 1) / totalActions) * 100
        } catch (error) {
          console.error('同步操作失败:', action, error)
          
          // 增加重试次数
          action.retryCount++
          action.error = error instanceof Error ? error.message : 'Unknown error'
          
          // 如果超过最大重试次数，移到失败队列
          if (action.retryCount >= action.maxRetries) {
            moveActionToFailed(action)
          }
        }
      }

      lastSyncTime.value = new Date()
      console.log('离线操作同步完成')

    } catch (error) {
      syncError.value = error instanceof Error ? error.message : 'Sync failed'
      console.error('同步过程中发生错误:', error)
    } finally {
      isSyncing.value = false
      syncProgress.value = 100
    }
  }

  // 执行离线操作
  async function executeOfflineAction(action: OfflineAction) {
    // 这里将在实际的云端同步功能中实现
    // 目前只是模拟执行
    console.log('执行离线操作:', action)
    
    // 模拟网络请求延迟
    await new Promise(resolve => setTimeout(resolve, 500))
    
    // 模拟可能的失败
    if (Math.random() < 0.1) { // 10% 失败率
      throw new Error('模拟网络错误')
    }
  }

  // 从队列中移除操作
  function removeActionFromQueues(actionId: string) {
    pendingActions.value = pendingActions.value.filter(a => a.id !== actionId)
    failedActions.value = failedActions.value.filter(a => a.id !== actionId)
  }

  // 将操作移到失败队列
  function moveActionToFailed(action: OfflineAction) {
    pendingActions.value = pendingActions.value.filter(a => a.id !== action.id)
    
    if (!failedActions.value.find(a => a.id === action.id)) {
      failedActions.value.push(action)
    }
  }

  // 重试失败的操作
  async function retryFailedActions() {
    if (!isOnline.value) {
      throw new Error('网络未连接，无法重试')
    }

    // 将失败的操作移回待处理队列
    const actionsToRetry = failedActions.value.map(action => ({
      ...action,
      retryCount: 0,
      error: undefined
    }))

    failedActions.value = []
    pendingActions.value.push(...actionsToRetry)

    // 开始同步
    await syncOfflineActions()
  }

  // 清除失败的操作
  function clearFailedActions() {
    failedActions.value = []
  }

  // 清除所有离线操作
  function clearAllActions() {
    pendingActions.value = []
    failedActions.value = []
  }

  // 手动触发同步
  async function manualSync() {
    if (!isOnline.value) {
      throw new Error('网络未连接，无法同步')
    }

    await syncOfflineActions()
  }

  // 获取离线统计
  function getOfflineStats() {
    return {
      isOnline: isOnline.value,
      connectionType: connectionType.value,
      pendingCount: pendingActions.value.length,
      failedCount: failedActions.value.length,
      totalCount: totalPendingCount.value,
      lastOnlineTime: lastOnlineTime.value,
      lastOfflineTime: lastOfflineTime.value,
      lastSyncTime: lastSyncTime.value,
      isSyncing: isSyncing.value,
      syncProgress: syncProgress.value
    }
  }

  // 设置离线提示
  function setOfflineMessage(message: string, show = true) {
    offlineMessage.value = message
    showOfflineIndicator.value = show
  }

  // 隐藏离线提示
  function hideOfflineIndicator() {
    showOfflineIndicator.value = false
  }

  // 检查网络连接质量
  async function checkConnectionQuality() {
    if (!isOnline.value) return 'offline'

    try {
      const start = Date.now()
      const response = await fetch('/api/ping', { 
        method: 'HEAD',
        cache: 'no-cache'
      })
      const duration = Date.now() - start

      if (response.ok) {
        if (duration < 100) return 'excellent'
        if (duration < 300) return 'good'
        if (duration < 1000) return 'fair'
        return 'poor'
      } else {
        return 'poor'
      }
    } catch (error) {
      return 'offline'
    }
  }

  // 清理资源
  function cleanup() {
    window.removeEventListener('online', handleOnline)
    window.removeEventListener('offline', handleOffline)
  }

  return {
    // 状态
    isOnline,
    connectionType,
    lastOnlineTime,
    lastOfflineTime,
    pendingActions,
    failedActions,
    isSyncing,
    syncProgress,
    syncError,
    lastSyncTime,
    showOfflineIndicator,
    offlineMessage,

    // 计算属性
    hasConnection,
    hasPendingActions,
    hasFailedActions,
    totalPendingCount,
    connectionStatus,

    // 方法
    setupNetworkListeners,
    updateNetworkStatus,
    addOfflineAction,
    syncOfflineActions,
    retryFailedActions,
    clearFailedActions,
    clearAllActions,
    manualSync,
    getOfflineStats,
    setOfflineMessage,
    hideOfflineIndicator,
    checkConnectionQuality,
    cleanup
  }
})