import { dataService } from './dataService.js'

/**
 * 自动刷新服务
 * 每天美东时间早上5点自动从数据库刷新数据
 */
class AutoRefreshService {
  constructor() {
    this.timerId = null
    this.targetHour = 5 // 美东早上5点
    this.isRunning = false
  }

  /**
   * 计算下一次美东早上5点的时间
   */
  getNextRefreshTime() {
    const now = new Date()
    
    // 获取美东时区的当前时间
    const etOptions = { timeZone: 'America/New_York', hour12: false }
    const etTimeString = now.toLocaleString('en-US', etOptions)
    const etDate = new Date(etTimeString)
    
    // 设置为美东早上5点
    const nextRefresh = new Date(etDate)
    nextRefresh.setHours(this.targetHour, 0, 0, 0)
    
    // 如果已经过了今天的5点，设置为明天
    if (etDate.getTime() >= nextRefresh.getTime()) {
      nextRefresh.setDate(nextRefresh.getDate() + 1)
    }
    
    // 转换回本地时区
    const etTimestamp = nextRefresh.getTime()
    const etOffset = this.getETOffset(nextRefresh)
    const localOffset = now.getTimezoneOffset() * 60 * 1000
    const localTimestamp = etTimestamp - etOffset + localOffset
    
    return new Date(localTimestamp)
  }

  /**
   * 获取美东时区的偏移量（毫秒）
   */
  getETOffset(date) {
    const etString = date.toLocaleString('en-US', { 
      timeZone: 'America/New_York',
      timeZoneName: 'short'
    })
    // EST is UTC-5, EDT is UTC-4
    const isDST = etString.includes('EDT')
    return isDST ? -4 * 60 * 60 * 1000 : -5 * 60 * 60 * 1000
  }

  /**
   * 执行刷新
   */
  async refresh() {
    console.log('[AutoRefresh] Refreshing data at', new Date().toLocaleString())
    try {
      await dataService.load(true)
      console.log('[AutoRefresh] Data refreshed successfully')
    } catch (error) {
      console.error('[AutoRefresh] Failed to refresh data:', error)
    }
  }

  /**
   * 调度下一次刷新
   */
  scheduleNext() {
    // 清除现有的定时器
    if (this.timerId) {
      clearTimeout(this.timerId)
      this.timerId = null
    }

    const nextRefresh = this.getNextRefreshTime()
    const now = new Date()
    const delay = nextRefresh.getTime() - now.getTime()

    console.log('[AutoRefresh] Next refresh scheduled at:', nextRefresh.toLocaleString())
    console.log('[AutoRefresh] Time until next refresh:', Math.round(delay / 1000 / 60), 'minutes')

    this.timerId = setTimeout(async () => {
      await this.refresh()
      this.scheduleNext() // 刷新后调度下一次
    }, delay)
  }

  /**
   * 启动自动刷新
   */
  start() {
    if (this.isRunning) {
      console.log('[AutoRefresh] Already running')
      return
    }

    console.log('[AutoRefresh] Starting auto-refresh service')
    this.isRunning = true
    this.scheduleNext()
  }

  /**
   * 停止自动刷新
   */
  stop() {
    console.log('[AutoRefresh] Stopping auto-refresh service')
    if (this.timerId) {
      clearTimeout(this.timerId)
      this.timerId = null
    }
    this.isRunning = false
  }

  /**
   * 手动触发刷新（不影响定时调度）
   */
  async triggerManualRefresh() {
    console.log('[AutoRefresh] Manual refresh triggered')
    await this.refresh()
  }
}

// 创建单例
export const autoRefreshService = new AutoRefreshService()