import mqtt from 'mqtt';

// 全局变量
let client= {
    instance : null,
    connected: false
} ;

/**
 * 初始化MQTT连接（无Promise，纯回调）
 * @param {Object} config 连接配置 {host, port, username, password, clientId, isSSL, keepalive, clean}
 * @param {Array} subs 订阅主题列表 [{topic: 'xxx', qos: 0}]
 */
export function initMQTT(config, subs = []) {
    // 1. 已有连接：直接回调成功
    if (client.instance && client.instance.connected) {
        return client;
    }

    const options = {
        clientId: 'uniapp_mqtt_' + Math.random().toString(16).substr(2, 8),
        username: config.username,
        password: config.password,
        clean: true,
        connectTimeout: 4000,
        reconnectPeriod: 1000
    }

    // 5. 构建连接参数
    const protocol = config.protocol || (config.isSSL ? 'wss' : 'ws');
    const url = `${protocol}://${config.host}:${config.port}/mqtt`

    client.instance = mqtt.connect(url, options)

    client.instance.on('connect', () => {
        client.connected = true
        client.instance.subscribe(subs, {qos: 0})
        console.info('已连接到MQTT服务器')
        console.info(client.instance)
    })

    client.instance.on('close', () => {
        console.info('连接已关闭')
        client.connected = false
        console.info(client.instance)
    })
}


/**
 * 断开MQTT连接（无Promise，纯回调）
 * @param {Function} onComplete 完成回调 () => {}
 */
export function disconnectMQTT() {
    if (client.instance && client.connected) {
        client.instance.end()
        client.connected = false
        console.info('已断开MQTT连接')
    }
}

/**
 * 获取MQTT客户端实例
 * @returns {Client} MQTT客户端
 */
export function getMQTTClientInstance() {
    return client.instance;
}

/**
 * 获取MQTT连接状态
 * @returns {Object} {isConnected: Boolean, isConnecting: Boolean}
 */
export function getMQTTStatus() {
    return {
        isConnected: !!client && client.connected,
    };
}