domotz-remote-pawn/src/amqp/handler.js

Domotz Agent

/** This file is part of Domotz Agent.
 * Copyright (C) 2016  Domotz Ltd
 *
 * Domotz Agent is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Domotz Agent is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Domotz Agent.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Created by Iacopo Papalini <iacopo@domotz.com> on 17/09/15.
 *
 * Process Messages incoming from the RabbitMQ command queue, instantiating the right class and calling the `execute`
 * method.
 *
 * If the message contains the `reply-to` property, a reply message is sent back, containing the result of the `execute`
 * call. By default it is JSON-encoded but other content types are supported
 *
 */

var factory = function (resourceLocator) {
    var myConsole = resourceLocator.log.decorateLogs();

    function parse(message) {
        var command = message.command;
        var tokens = command.toLowerCase().split('_');
        command = tokens.shift();
        for (var i = 0; i < tokens.length; i++) {
            command += tokens[i].charAt(0).toUpperCase() + tokens[i].slice(1);
        }
        myConsole.verbose('Parsed command: %s', command);
        return command;
    }

    function createCommandFromMessage(message) {
        var command = parse(message);
        if (command.indexOf('ssh') !== -1) {
            command = 'ssh/' + command;
        }
        if (!resourceLocator.settingsManager.isCommandHandlerEnabled(command)) {
            myConsole.warn('(%s) command disabled from settings', command);
            return null;
        }
        var commandModule = require('../commands/' + command + '.js');
        return commandModule.command(message, resourceLocator);
    }

    function callback(payload, options) {
        if (options === undefined) {
            options = {};
        }
        if (payload === undefined || payload === null) {
            myConsole.debug('Sending empty message as ack');
            return new Buffer(JSON.stringify({}));
        }
        if (payload instanceof Object && !options.asBinary) {
            return new Buffer(JSON.stringify(payload));
        }
        myConsole.debug('handling returned payload as binary - no transformation');
        return new Buffer(payload, 'binary');
    }

    function processMessage(channel, exchange, amqpMessage) {
        var message, cid, replyTo;
        var command;
        if (!amqpMessage) {
            throw new Error('MESSAGE - Received an empty message');
        }
        message = JSON.parse(amqpMessage.content.toString());
        cid = amqpMessage.properties.correlationId;
        replyTo = amqpMessage.properties.replyTo;
        myConsole.debug('MESSAGE - (%s): Received', cid);
        message.correlationId = cid;
        myConsole.debug('MESSAGE row ' + JSON.stringify(message));
        command = createCommandFromMessage(message);
        if (command === null) {
            var buffer = callback({ error: 'COMMAND_DISABLED_BY_SETTINGS' }, {});
            var properties = { correlationId: cid };
            channel.publish(exchange, replyTo, buffer, properties);
            return;
        }
        myConsole.info('MESSAGE - (%s): %s', cid, command.describe());
        command.execute(buildExecutionResponseHandler(cid, replyTo, channel, exchange));
    }

    function buildExecutionResponseHandler(cid, replyTo, channel, exchange) {
        return function (payload, error, options) {
            if (replyTo === null || replyTo === undefined) {
                myConsole.info('MESSAGE - (%s): without reply-to - not sending reply', cid);
                return;
            }
            var buffer = callback(payload, options);
            // TODO Handler error
            myConsole.info('MESSAGE - (%s): Sending reply on queue %s - size in bytes: %d', cid, replyTo, buffer.length);
            var properties = { correlationId: cid };
            if (options && options.asBinary) {
                myConsole.info('MESSAGE - (%s): content-type: %s', cid, options['content-type']);
                properties.contentType = options['content-type'];
            }
            channel.publish(exchange, replyTo, buffer, properties);
        };
    }

    return {
        processMessage: processMessage,
        // For testing
        _createCommandFromMessage: createCommandFromMessage,
        _callback: callback,
        _parse: parse,
        _buildExecutionResponseHandler: buildExecutionResponseHandler,
    };
};

module.exports.factory = factory;