APP/utils/mqtt.js

import mqtt from 'mqtt/dist/mqtt.js';

const MQTT_BROKER_URL = 'ws://your-mqtt-broker-address:your-port/mqtt'; // 使用 ws:// 或 wss://
const MQTT_OPTIONS = {
    connectTimeout: 4000,
    clientId: `mqtt_client_${Math.random().toString(16).substr(2, 8)}`,
    username: 'your-username', 
    password: 'your-password', 
    clean: true, 
};

let client = null;
let connectPromise = null; 

// 连接到 MQTT 代理
export function connect() {
    if (client && client.connected) {
        return Promise.resolve(client);
    }
    if (connectPromise) {
        return connectPromise;
    }

    let url = MQTT_BROKER_URL;
    // #ifdef MP-WEIXIN || APP-PLUS
    // #endif

    console.log(`正在连接到 MQTT 代理: ${url}`);
    client = mqtt.connect(url, MQTT_OPTIONS);

    connectPromise = new Promise((resolve, reject) => {
        client.on('connect', () => {
            console.log('MQTT 已连接');
            connectPromise = null;
            resolve(client);
        });

        client.on('reconnect', () => {
            console.log('MQTT 正在重新连接...');
        });

        client.on('error', (err) => {
            console.error('MQTT 连接错误:', err);
            if (connectPromise) { 
                reject(err);
            }
            connectPromise = null; 
        });

        client.on('close', () => {
            console.log('MQTT 连接已关闭');
            connectPromise = null;
        });

        client.on('offline', () => {
            console.log('MQTT 客户端离线');
            connectPromise = null;
        });
    });

    return connectPromise;
}

// 断开 MQTT 连接
export function disconnect() {
    return new Promise((resolve) => {
        if (client) {
            console.log('正在断开 MQTT 客户端...');
            client.end(true, (err) => { // true 表示强制关闭，丢弃未发送的消息
                if (err) {
                    console.error('MQTT 断开连接时出错:', err);
                } else {
                    console.log('MQTT 已成功断开连接');
                }
                client = null;
                connectPromise = null;
                resolve();
            });
        } else {
            resolve();
        }
    });
}

// 发布消息
export async function publish(topic, message, options = { qos: 0, retain: false }) {
    if (!client || !client.connected) {
        console.warn('MQTT 客户端未连接。正在尝试连接...');
        try {
            await connect(); // 发布前确保已连接
        } catch (error) {
            console.error('发布前连接失败:', error);
            uni.showToast({ title: 'MQTT 连接失败', icon: 'none' });
            return Promise.reject('MQTT 客户端未连接');
        }
    }

    return new Promise((resolve, reject) => {
        client.publish(topic, message, options, (err) => {
            if (err) {
                console.error('MQTT 发布错误:', err);
                reject(err);
            } else {
                console.log(`MQTT 消息已发布到主题 ${topic}:`, message);
                resolve();
            }
        });
    });
}

// 订阅主题
export async function subscribe(topic, options = { qos: 0 }) {
     if (!client || !client.connected) {
        console.warn('MQTT 客户端未连接。正在尝试连接...');
        try {
            await connect(); // 订阅前确保已连接
        } catch (error) {
            console.error('订阅前连接失败:', error);
            uni.showToast({ title: 'MQTT 连接失败', icon: 'none' });
            return Promise.reject('MQTT 客户端未连接');
        }
    }
    return new Promise((resolve, reject) => {
        client.subscribe(topic, options, (err, granted) => {
            if (err) {
                console.error('MQTT 订阅错误:', err);
                reject(err);
            } else {
                console.log(`MQTT 已订阅主题: ${granted[0].topic} 服务质量 (QoS): ${granted[0].qos}`);
                resolve(granted);
            }
        });
    });
}

// 取消订阅主题
export function unsubscribe(topic) {
    return new Promise((resolve, reject) => {
        if (client && client.connected) {
            client.unsubscribe(topic, (err) => {
                if (err) {
                    console.error('MQTT 取消订阅错误:', err);
                    reject(err);
                } else {
                    console.log(`MQTT 已取消订阅主题: ${topic}`);
                    resolve();
                }
            });
        } else {
            console.warn('MQTT 客户端未连接，无法取消订阅。');
            resolve();
        }
    });
}

// 处理传入的消息
export function onMessage(callback) {
    if (client) {
        client.on('message', callback); // 回调格式: (topic, message, packet) => { ... }
    } else {
        const checkClientInterval = setInterval(() => {
            if (client) {
                client.on('message', callback);
                clearInterval(checkClientInterval);
            } else if (connectPromise === null && client === null) {
                 console.warn('MQTT 客户端未初始化以处理 onMessage，且没有连接尝试正在进行中。');
                 clearInterval(checkClientInterval);
            }
        }, 100);
    }
}
export function getClient() {
    return client;
}

export function isConnected() {
    return client && client.connected;
}