// rabbitmq-live-client.js  (CommonJS)
const amqp = require('amqplib');
const { EventEmitter } = require('events');

const CFG = {
    protocol: process.env.RABBIT_PROTOCOL || 'amqp', // 'amqp' | 'amqps'
    // host: process.env.RABBIT_HOST || '192.168.1.144',
    host: process.env.RABBIT_HOST || 'crawlclient.api.yolozs.com',
    port: Number(process.env.RABBIT_PORT || 5672),
    user: process.env.RABBIT_USER || 'tkdata',
    pass: process.env.RABBIT_PASS || '6rARaRj8Z7UG3ahLzh',
    vhost: process.env.RABBIT_VHOST || '/',
    heartbeat: Number(process.env.RABBIT_HEARTBEAT || 60), // <-- 关键：心跳
    frameMax: Number(process.env.RABBIT_FRAME_MAX || 0),  // 0=默认；可调大以减少分片
};

let conn = null;
let pubCh = null; // 发布 Confirm Channel
let conCh = null; // 消费 Channel
const emitter = new EventEmitter();

const consumers = new Map(); // queueName -> { onMessage, options, consumerTag }

let reconnecting = false;
let closing = false;
let backoff = 1000; // ms
const MAX_BACKOFF = 15000;
let reconnectTimer = null;

// —— 工具：序列化消息
function toBuffer(payload) {
    if (Buffer.isBuffer(payload)) return payload;
    if (typeof payload === 'string') return Buffer.from(payload);
    return Buffer.from(JSON.stringify(payload));
}

// —— 内部：建立连接（含心跳、keepalive、事件）
async function createConnection() {
    const connection = await amqp.connect({
        protocol: CFG.protocol,
        hostname: CFG.host,
        port: CFG.port,
        username: CFG.user,
        password: CFG.pass,
        vhost: CFG.vhost,
        heartbeat: CFG.heartbeat,
        frameMax: CFG.frameMax > 0 ? CFG.frameMax : undefined,
        // 也可用 URL 形式：`amqp://u:p@host:5672/vhost?heartbeat=60`
    });

    // 打开 TCP keepalive，降低 NAT/空闲超时断开的概率
    try {
        const stream = connection.stream || connection.socket;
        if (stream?.setKeepAlive) stream.setKeepAlive(true, 15_000); // 15s
    } catch (_) { }

    connection.on('error', (e) => {
        // 心跳超时常见，避免重复噪音
        const msg = e?.message || String(e);
        if (msg && /heartbeat/i.test(msg)) {
            console.error('[AMQP] connection error (heartbeat):', msg);
        } else {
            console.error('[AMQP] connection error:', msg);
        }
        emitter.emit('error', e);
    });

    connection.on('close', () => {
        if (closing) return; // 正在关闭时不重连
        console.error('[AMQP] connection closed');
        conn = null; pubCh = null; conCh = null;
        scheduleReconnect();
    });

    // Broker 侧内存/磁盘压力会 block 连接
    connection.on('blocked', (reason) => {
        console.warn('[AMQP] connection blocked by broker:', reason);
        emitter.emit('blocked', reason);
    });
    connection.on('unblocked', () => {
        console.log('[AMQP] connection unblocked');
        emitter.emit('unblocked');
    });

    console.log(`[AMQP] connected to ${CFG.host} (hb=${CFG.heartbeat}s)`);
    return connection;
}

// —— 内部：确保连接和通道存在
async function ensureChannels() {
    if (!conn) conn = await createConnection();

    if (!pubCh) {
        pubCh = await conn.createConfirmChannel();
        pubCh.on('error', e => console.error('[AMQP] pub channel error:', e?.message || e));
        pubCh.on('close', () => { pubCh = null; if (!closing) scheduleReconnect(); });
    }

    if (!conCh) {
        conCh = await conn.createChannel();
        conCh.on('error', e => console.error('[AMQP] con channel error:', e?.message || e));
        conCh.on('close', () => { conCh = null; if (!closing) scheduleReconnect(); });
    }
}

// —— 内部：安排重连（指数退避 + 抖动，且只触发一个循环）
function scheduleReconnect() {
    if (reconnecting || closing) return;
    reconnecting = true;
    if (reconnectTimer) { clearTimeout(reconnectTimer); reconnectTimer = null; }

    const attempt = async () => {
        if (closing) return;
        try {
            await ensureChannels();
            await resumeConsumers(); // 恢复所有消费
            reconnecting = false;
            backoff = 1000;
            emitter.emit('reconnected');
            console.log('[AMQP] reconnected and consumers resumed');
        } catch (e) {
            const base = Math.min(backoff, MAX_BACKOFF);
            // 加抖动，避免雪崩：在 75%~125% 之间浮动
            const jitter = base * (0.75 + Math.random() * 0.5);
            console.warn(`[AMQP] reconnect failed: ${e?.message || e}; retry in ${Math.round(jitter)}ms`);
            backoff = Math.min(backoff * 1.6, MAX_BACKOFF);
            reconnectTimer = setTimeout(attempt, jitter);
        }
    };

    reconnectTimer = setTimeout(attempt, backoff);
}

// —— 内部：恢复所有消费者
async function resumeConsumers() {
    if (!conCh) return;
    for (const [queue, c] of consumers.entries()) {
        try {
            if (c.consumerTag) await conCh.cancel(c.consumerTag);
        } catch (_) { }
        const tag = await startOneConsumer(queue, c.onMessage, c.options, true);
        c.consumerTag = tag.consumerTag;
    }
}

// —— 内部：启动一个消费者
async function startOneConsumer(queueName, onMessage, options = {}, isResume = false) {
    await ensureChannels();

    const {
        prefetch = 1,
        durable = true,
        assertQueue = true,
        requeueOnError = false,
        // 可选：exclusive, arguments, dead-letter 等
    } = options;

    if (assertQueue) {
        await conCh.assertQueue(queueName, { durable });
    }
    await conCh.prefetch(prefetch);

    const consumeResult = await conCh.consume(
        queueName,
        async (msg) => {
            if (!msg) return;
            const raw = msg.content;
            const text = raw?.toString?.() ?? '';
            let json;
            try { json = JSON.parse(text); } catch (_) { /* 忽略解析失败 */ }

            const payload = {
                raw, text, json,
                fields: msg.fields,
                properties: msg.properties,
                ack: () => { try { conCh.ack(msg); } catch (_) { } },
                nack: (requeue = requeueOnError) => { try { conCh.nack(msg, false, requeue); } catch (_) { } },
            };

            try {
                emitter.emit('message', queueName, payload);
                await onMessage(payload);     // 业务回调
                payload.ack();
            } catch (err) {
                emitter.emit('handlerError', queueName, err, payload);
                payload.nack(requeueOnError);
            }
        },
        { noAck: false }
    );

    if (!isResume) {
        consumers.set(queueName, { onMessage, options, consumerTag: consumeResult.consumerTag });
    }

    console.log(`[*] consuming "${queueName}" (prefetch=${prefetch})`);
    return consumeResult;
}

// —— 对外 API：启动消费
async function startConsumer(queueName, onMessage, options = {}) {
    if (!queueName) throw new Error('queueName 必填');
    if (typeof onMessage !== 'function') throw new Error('onMessage 回调必填');
    const res = await startOneConsumer(queueName, onMessage, options, false);
    return {
        emitter,
        async stop() {
            const c = consumers.get(queueName);
            if (c?.consumerTag && conCh) {
                await conCh.cancel(c.consumerTag).catch(() => { });
            }
            consumers.delete(queueName);
            return res;
        }
    };
}

// —— 对外 API：发送到队列（支持 confirm）
async function publishToQueue(queueName, payload, options = {}) {
    if (!queueName) throw new Error('queueName 必填');
    await ensureChannels();

    const {
        durable = true,
        persistent = true,
        assertQueue = true,
        confirm = true,
        headers = {},
        mandatory = false, // 可选：不可路由返回
    } = options;

    if (assertQueue) {
        await pubCh.assertQueue(queueName, { durable });
    }

    const ok = pubCh.sendToQueue(queueName, toBuffer(payload), { persistent, headers, mandatory });
    if (!ok) await new Promise(r => pubCh.once('drain', r));
    if (confirm) await pubCh.waitForConfirms();
}

// —— 对外 API：发送到交换机（支持 confirm）
async function publishToExchange(exchange, routingKey, payload, options = {}) {
    if (!exchange) throw new Error('exchange 必填');
    await ensureChannels();

    const {
        type = 'direct',
        durable = true,
        assertExchange = true,
        confirm = true,
        persistent = true,
        headers = {},
        mandatory = false,
    } = options;

    if (assertExchange) {
        await pubCh.assertExchange(exchange, type, { durable });
    }

    const ok = pubCh.publish(exchange, routingKey || '', toBuffer(payload), { persistent, headers, mandatory });
    if (!ok) await new Promise(r => pubCh.once('drain', r));
    if (confirm) await pubCh.waitForConfirms();
}

// —— 对外 API：主动重连（给 Electron 恢复/网络变化时调用）
async function reconnectNow() {
    if (closing) return;
    if (reconnecting) return;
    try {
        if (pubCh) await pubCh.close().catch(() => { });
        if (conCh) await conCh.close().catch(() => { });
        if (conn) await conn.close().catch(() => { });
    } catch (_) { }
    pubCh = null; conCh = null; conn = null;
    reconnecting = false;
    scheduleReconnect();
}

// —— 关闭
async function close() {
    closing = true;
    if (reconnectTimer) { clearTimeout(reconnectTimer); reconnectTimer = null; }
    try {
        // 取消所有消费者
        for (const [q, c] of consumers.entries()) {
            if (c?.consumerTag && conCh) {
                await conCh.cancel(c.consumerTag).catch(() => { });
            }
        }
    } catch (_) { }
    consumers.clear();

    try { if (pubCh) await pubCh.close(); } catch (_) { }
    try { if (conCh) await conCh.close(); } catch (_) { }
    try { if (conn) await conn.close(); } catch (_) { }
    pubCh = null; conCh = null; conn = null;
}

// —— 进程信号（可选）
process.once('SIGINT', async () => { try { await close(); } finally { process.exit(0); } });
process.once('SIGTERM', async () => { try { await close(); } finally { process.exit(0); } });

module.exports = {
    startConsumer,
    publishToQueue,
    publishToExchange,
    reconnectNow,
    close,
    emitter, // 可订阅 'message' / 'handlerError' / 'reconnected' / 'error' / 'blocked' / 'unblocked'
};