import { Bot } from 'grammy'
import { registerHandlers } from './handlers'
import { closeConnectionsForPlatform } from '@/remote-control/shared/nova-bridge'
import { BotLogger } from '@/remote-control/shared/logger'
import { ConfigManager, type ConfigChangeEvent } from '@/remote-control/config/manager'

const CONNECTION_TIMEOUT = 30_000 // 30s to establish first connection

let bot: Bot | null = null
let currentToken: string = ''
let isConnected: boolean = false
let connectTimer: ReturnType<typeof setTimeout> | null = null
let startTime: number = 0
let messagesProcessed: number = 0
let lastError: Error | null = null

export interface BotStatus {
  platform: string
  status: 'connected' | 'disconnected' | 'connecting'
  uptime?: number
  messagesProcessed: number
  error?: string
}

export async function startBot(token: string): Promise<void> {
  if (!token) {
    const msg = 'Telegram Bot Token 为空，跳过启动'
    console.warn(`[Telegram Bot] ${msg}`)
    BotLogger.log({ platform: 'telegram', eventType: 'error', severity: 'warning', message: msg })
    return
  }

  // Idempotent check
  if (bot && currentToken === token) {
    console.log('[Telegram Bot] 已有活跃连接，跳过重复启动')
    return
  }

  // If token changed, stop old bot first
  if (bot) {
    console.log('[Telegram Bot] Token 已变更，先停止旧连接')
    await stopBot()
  }

  currentToken = token

  try {
    bot = new Bot(token)

    bot.catch((err) => {
      lastError = err.error instanceof Error ? err.error : new Error(String(err.error))
      console.error('[Telegram Bot] 运行时错误:', lastError.message)
      BotLogger.log({
        platform: 'telegram',
        eventType: 'error',
        severity: 'error',
        message: `Telegram Bot 运行时错误: ${lastError.message}`,
      })
    })

    registerHandlers(bot, token, () => { messagesProcessed++ })

    // Connection timeout — if onStart is not called within CONNECTION_TIMEOUT,
    // stop the bot and mark as disconnected
    connectTimer = setTimeout(() => {
      if (!isConnected && bot) {
        const msg = '连接超时，请检查 Token 是否正确以及网络是否可达'
        lastError = new Error(msg)
        console.error(`[Telegram Bot] ${msg}`)
        BotLogger.log({ platform: 'telegram', eventType: 'error', severity: 'error', message: msg })
        void stopBot()
      }
    }, CONNECTION_TIMEOUT)

    // Start long polling (non-blocking).
    // bot.start() returns a promise that resolves when bot.stop() is called,
    // so we must NOT await it. Connection errors surface via bot.catch().
    bot.start({
      onStart: (botInfo) => {
        if (connectTimer) { clearTimeout(connectTimer); connectTimer = null }
        isConnected = true
        startTime = Date.now()
        lastError = null
        console.log(`[Telegram Bot] 已启动: @${botInfo.username}`)
        BotLogger.log({
          platform: 'telegram',
          eventType: 'connection',
          severity: 'info',
          message: `Telegram Bot 已连接，用户名: @${botInfo.username}`,
        })
      },
    }).catch((err) => {
      // Long polling loop ended with error (e.g. invalid token, network issue)
      if (connectTimer) { clearTimeout(connectTimer); connectTimer = null }
      const error = err instanceof Error ? err : new Error(String(err))
      if (error.message === 'Aborted delay') return // Normal stop, ignore
      lastError = error
      isConnected = false
      console.error('[Telegram Bot] 长轮询异常退出:', error.message)
      BotLogger.log({
        platform: 'telegram',
        eventType: 'error',
        severity: 'error',
        message: `Telegram Bot 长轮询异常: ${error.message}`,
      })
    })
  } catch (err) {
    const error = err instanceof Error ? err : new Error(String(err))
    lastError = error
    bot = null
    currentToken = ''
    isConnected = false
    console.error('[Telegram Bot] 启动失败:', error.message)
    BotLogger.log({
      platform: 'telegram',
      eventType: 'error',
      severity: 'error',
      message: `Telegram Bot 启动失败: ${error.message}`,
      details: { hint: '请检查 Bot Token 是否正确，以及是否已在 @BotFather 中创建了 Bot' },
    })
    throw error
  }
}

export async function stopBot(): Promise<void> {
  if (connectTimer) { clearTimeout(connectTimer); connectTimer = null }
  closeConnectionsForPlatform('telegram')
  if (bot) {
    try {
      await bot.stop()
    } catch {
      // "Aborted delay" is expected when stopping long polling — ignore
    }
    bot = null
    currentToken = ''
    isConnected = false
    startTime = 0
    console.log('[Telegram Bot] 已停止')
    BotLogger.log({
      platform: 'telegram',
      eventType: 'disconnection',
      severity: 'info',
      message: 'Telegram Bot 已停止',
    })
  }
}

export function getStatus(): BotStatus {
  return {
    platform: 'telegram',
    status: isConnected ? 'connected' : bot ? 'connecting' : 'disconnected',
    uptime: isConnected && startTime ? Math.floor((Date.now() - startTime) / 1000) : undefined,
    messagesProcessed,
    error: lastError?.message,
  }
}

// Listen for config changes
const configManager = ConfigManager.getInstance()
configManager.on('config-changed', async (event: ConfigChangeEvent) => {
  const { newConfig } = event
  const platformConfig = newConfig.telegram

  try {
    if (platformConfig.enabled && !bot) {
      await startBot(platformConfig.botToken)
    } else if (!platformConfig.enabled && bot) {
      await stopBot()
    } else if (platformConfig.enabled && bot) {
      if (platformConfig.botToken !== currentToken) {
        await stopBot()
        await startBot(platformConfig.botToken)
      }
    }
    lastError = null
  } catch (error) {
    lastError = error instanceof Error ? error : new Error(String(error))
    BotLogger.log({
      platform: 'telegram',
      eventType: 'error',
      severity: 'error',
      message: `配置变更处理失败: ${lastError.message}`,
    })
  }
})