FredericHeem/rabbitmq-pubsub

'use strict';
const amqp = require('amqplib');
const _ = require('lodash');
const util = require('util');

let log;

export default class Subscriber {
    constructor(options = {}, logOptions) {
        log = require('logfilename')(__filename, logOptions);
        if(!options.exchange){
            throw new Error('exchange parameter missing in options');
        }
        if(!options.queueName){
            throw new Error('queueName parameter missing in options');
        }
        this._queue;
        this._channel;
        this._options = _.defaults(options, {
            type: 'topic',
            url: 'amqp://localhost'
        });
        log.info('Subscriber options:', util.inspect(this._options));
    }

    async start(onIncomingMessage) {
        log.info('start');

        let options = this._options;
        let connection = await amqp.connect(options.url);
        log.info('createChannel');
        this._channel = await connection.createChannel();
        log.info('assertExchange ', options.exchange);
        await this._channel.assertExchange(options.exchange, options.type, { durable: true });
        log.info('assertQueue name: ', options.queueName);
        let result = await this._channel.assertQueue(options.queueName, { exclusive: false });

        this._queue = result.queue;
        let routingKeys = options.routingKeys || [options.queueName];
        log.info('assertQueue keys ', routingKeys);
        for(let routingKey of routingKeys){
            log.info('bindQueue routingKey ', routingKey);
            await this._channel.bindQueue(this._queue, options.exchange, routingKey);
        }

        log.info('prefetch and consume');
        this._channel.prefetch(1);
        await this._channel.consume(this._queue, onIncomingMessage.bind(this));
        log.info('started');
    }
    async stop() {
        log.info('stop');
        if (this._channel) {
            return await this._channel.close();
        } else {
            log.warn('stopping but channel was not opened');
        }
    }
    ack(message) {
        log.debug('ack');
        this._channel.ack(message);
    }
    nack(message) {
        log.debug('nack');
        this._channel.nack(message);
    }
    async purgeQueue() {
        log.info('purgeQueue ', this._queue);
        if (this._channel) {
            return await this._channel.purgeQueue(this._queue);
        } else {
            log.warn('purgeQueue: channel not opened');
        }
    }
}