sokolov-sbs-flowserver/flow/mqttsubscribe.js

exports.id = 'mqttsubscribe';
exports.title = 'MQTT subscribe';
exports.group = 'MQTT';
exports.color = '#888600';
exports.version = '1.1.0';
exports.icon = 'sign-in';
exports.output = 1;
exports.variables = true;
exports.author = 'Martin Smola';
exports.options = {};

exports.html = `<div class="padding">
	<div data-jc="dropdown" data-jc-path="broker" data-jc-config="datasource:mqttconfig.brokers;required:true" class="m">@(Select a broker)</div>
	<div data-jc="textbox" data-jc-path="topic" data-jc-config="placeholder:hello/world;required:true">Topic</div>
	<div class="help m">@(Supports variables, example: \`device/{device-id}\`)</div>
	<div data-jc="dropdown" data-jc-path="qos" data-jc-config="items:,0,1,2" class="m">@(QoS)</div>
</div>
<script>
	var mqttconfig = { brokers: [] };
	ON('open.mqttsubscribe', function(component, options) {
		TRIGGER('mqtt.brokers', 'mqttconfig.brokers');
	});
	ON('save.mqttsubscribe', function(component, options) {
		!component.name && (component.name = options.broker + (options.topic ? ' -> ' + options.topic : ''));
	});
</script>`;

exports.readme = `
# MQTT subscribe

The data recieved are passed to the output as follows:
\`\`\`javascript
{
	topic: '/lights/on',
	data: 'kitchen'
}
\`\`\`

If the topic is wildcard then there's an array of matches in flowdata repository which can be used in Function component like so:
\`\`\`javascript
// wildcard -> /+/status
// topic -> /devicename/status

var match = flowdata.get('mqtt_wildcard');
// match === ['devicename']
\`\`\`
 
More on wildcard topics [here](https://mosquitto.org/man/mqtt-7.html)
`;

exports.install = function(instance) {

	var old_topic;
	var ready = false;

	instance.custom.reconfigure = function(o, old_options) {


		ready = false;

		if (!MQTT.broker(instance.options.broker)) 
			return instance.status('No broker', 'red');

		if (instance.options.broker && instance.options.topic) {

			if (old_topic)
				MQTT.unsubscribe(instance.options.broker, instance.id, old_topic);

			old_topic = instance.arg(instance.options.topic);
			MQTT.subscribe(instance.options.broker, instance.id, old_topic);
			ready = true;
			return;
		}

		instance.status('Not configured', 'red');
	};

	instance.on('options', instance.custom.reconfigure);

	instance.on('close', function() {
		MQTT.unsubscribe(instance.options.broker, instance.id, instance.options.topic);
		OFF('mqtt.brokers.message', instance.custom.message);
		OFF('mqtt.brokers.status', instance.custom.brokerstatus);
	});

	instance.custom.brokerstatus = function(status, brokerid, msg) {
		if (brokerid !== instance.options.broker)
			return;

		switch (status) {
			case 'connecting':
				instance.status('Connecting', '#a6c3ff');
				break;
			case 'connected':
				instance.status('Connected', 'green');
				break;
			case 'disconnected':
				instance.status('Disconnected', 'red');
				break;
			case 'connectionfailed':
				instance.status('Connection failed', 'red');
				break;
			case 'new':
				!ready && instance.custom.reconfigure();
				break;
			case 'removed':
				instance.custom.reconfigure();
				break;
			case 'error':
				instance.status(msg, 'red');
				break;
			case 'reconfigured':
				instance.options.broker = msg;
				instance.reconfig();
				instance.custom.reconfigure();
				break;
		}
	}

	instance.custom.message = function(brokerid, topic, message) {
		if (brokerid !== instance.options.broker)
			return;

		var match = mqttWildcard(topic, old_topic);
		if (match) {
			var flowdata = instance.make({ topic: topic, data: message })
			flowdata.set('mqtt_wildcard', match);
			instance.send2(flowdata);
		}
	}

	ON('mqtt.brokers.message', instance.custom.message);
	ON('mqtt.brokers.status', instance.custom.brokerstatus);

	instance.custom.reconfigure();
};

// https://github.com/hobbyquaker/mqtt-wildcard
function mqttWildcard(topic, wildcard) {
    if (topic === wildcard) {
        return [];
    } else if (wildcard === '#') {
        return [topic];
    }

    var res = [];

    var t = String(topic).split('/');
    var w = String(wildcard).split('/');

    var i = 0;
    for (var lt = t.length; i < lt; i++) {
        if (w[i] === '+') {
            res.push(t[i]);
        } else if (w[i] === '#') {
            res.push(t.slice(i).join('/'));
            return res;
        } else if (w[i] !== t[i]) {
            return null;
        }
    }

    if (w[i] === '#') {
        i += 1;
    }

    return (i === w.length) ? res : null;
}