// useMqtt.ts
import { ref, onUnmounted } from 'vue'
import mqtt, { MqttClient, IClientOptions } from 'mqtt'
import { ElMessage } from 'element-plus'

type MessageCallback = (topic: string, payload: any) => void

// 基础配置 (建议移至环境变量 import.meta.env.VITE_MQTT_HOST)
const BASE_OPTIONS: IClientOptions = {
  clean: true,
  reconnectPeriod: 5000,
  connectTimeout: 10000,
  username: 'yanfan',
  password:
    'eyJhbGciOiJIUzUxMiJ9.eyJsb2dpbl91c2VyX2tleSI6IjY0YmM2NjJlLWZhMjQtNGY1Ny1hOTk1LWZiMGM2YjNhYzI4OCJ9.9nxoDUNGTk1szRlZHHG0AcWZctLrzJ16UA5rsBagHNcD10PC-LIMTgAr2CK1Ppafa6cW5XPdn7RqBF6iZjHtww'
}

export function useMqtt() {
  const client = ref<MqttClient | null>(null)
  const isConnected = ref(false)
  const message = ref<any>(null) // 响应式消息数据

  let customMessageCallback: MessageCallback | null = null

  // 初始化连接
  const connect = (host: string, options: IClientOptions = {}, onMessage?: MessageCallback) => {
    if (client.value && client.value.connected) {
      console.warn('当前实例已连接 MQTT，跳过初始化')
      return
    }

    if (onMessage) {
      customMessageCallback = onMessage
    }

    // 合并配置，生成唯一 ClientId
    const finalOptions = {
      ...BASE_OPTIONS,
      clientId: `web-${Math.random().toString(16).substr(2)}`,
      ...options
    }

    try {
      client.value = mqtt.connect(host, finalOptions)

      client.value.on('connect', () => {
        isConnected.value = true
        ElMessage.success('MQTT 连接成功')
      })

      client.value.on('error', (err) => {
        console.error('MQTT Error:', err)
        ElMessage.error(`MQTT 错误: ${err.message}`)
        isConnected.value = false
      })

      client.value.on('close', () => {
        isConnected.value = false
      })

      // 全局消息监听，更新响应式数据
      client.value.on('message', (topic, payload) => {
        let parsedData: any
        try {
          parsedData = JSON.parse(payload.toString())
        } catch (e) {
          parsedData = payload.toString()
        }

        message.value = { topic, payload: parsedData }

        if (customMessageCallback) {
          customMessageCallback(topic, parsedData)
        }
      })
    } catch (err) {
      ElMessage.error(`MQTT 初始化异常: ${(err as Error).message}`)
      isConnected.value = false
    }
  }

  // 订阅主题 (支持泛型)
  const subscribe = (topic: string) => {
    if (client.value && client.value.connected) {
      client.value.subscribe(topic, { qos: 0 }, (err) => {
        if (err) ElMessage.error(`订阅失败: ${err.message}`)
        else console.log(`已订阅: ${topic}`)
      })
    }
  }

  // 发布消息
  const publish = (topic: string, message: string | object) => {
    if (client.value && client.value.connected) {
      const payload = typeof message === 'string' ? message : JSON.stringify(message)
      client.value.publish(topic, payload)
    }
  }

  // 销毁连接
  const destroy = () => {
    if (client.value) {
      client.value.end()
      client.value = null
      isConnected.value = false
    }
  }

  // 组件卸载时自动断开 (防止内存泄漏)
  onUnmounted(() => {
    destroy()
  })

  return {
    client,
    isConnected,
    message, // 组件内可以直接 watch 这个变量
    connect,
    subscribe,
    publish,
    destroy
  }
}