nixfilter-mqtt/utils.coffee

Filters for publishing and subscribing to MQTT topics, similar to "mosquitto_pub" and "mosquitto_sub"

'use strict'

# Add those arguments to <argument_parser> that all filter have in common
add_common_arguments = (argument_parser) ->
	argument_parser.addArgument ['--host', '--broker', '-b'],
		defaultValue: 'localhost'
		help: 'The hostname or IP address of the MQTT broker'
	argument_parser.addArgument ['--port', '-P'],
		type: 'int'
		defaultValue: 1883
		help: 'The port of the MQTT broker'
	argument_parser.addArgument ['--username', '-u'],
		help: 'The username to use when connecting'
	argument_parser.addArgument ['--password', '-p'],
		help: 'The password to use when connecting'
	argument_parser.addArgument ['--client_id', '-c'],
		help: 'The client ID to use when connecting'
	argument_parser.addArgument ['--qos', '-q'],
		type: 'int'
		choices: [0, 1, 2]
		defaultValue: 0
		help: 'The QOS level to use'
	argument_parser.addArgument ['--status_topic', '-s'],
		help: 'The (optional) MQTT topic to publish online/offline status messages to'
	argument_parser.addArgument ['--online_message'],
		defaultValue: 'online'
		help: 'The (retained) message to publish to the (optional) MQTT topic when going online'
	argument_parser.addArgument ['--offline_message'],
		defaultValue: 'offline'
		help: 'The (retained) message to publish to the (optional) MQTT topic when going offline'
	argument_parser

# Require the "mqtt" module
mqtt = require('mqtt')

# Connect to the MQTT broker, using the arguments/parameters in <args>
connect_to_mqtt_broker = (args) ->
	new Promise (resolve, reject) =>
		connect_options =
			servers: [
				host: args.host
				port: args.port
			]
			clientId: args.client_id
		if args.username
			connect_options.username = args.username
			connect_options.password = args.password
		if args.status_topic
			connect_options.will =
				topic: args.status_topic
				payload: args.offline_message
				qos: args.qos
				retain: true
		mqtt_client = mqtt.connect(connect_options)
		mqtt_client.once 'connect', =>
			if args.status_topic
				mqtt_client.publish args.status_topic, args.online_message,
					qos: args.qos
					retain: true
			resolve(mqtt_client)
			return
		mqtt_client.once 'error', (error) =>
			reject(error)
			return
		mqtt_client.once 'close', =>
			reject("Unable to connect to MQTT broker #{args.host}:#{args.port}")
			return
		return

# Disconnect MQTT client <mqtt_client> from the MQTT broker it is connected to
disconnect_from_mqtt_broker = (mqtt_client) ->
	new Promise (resolve, reject) =>
		mqtt_client.end ->
			resolve(mqtt_client)
		return

# What this module exports
module.exports =
	add_common_arguments: add_common_arguments
	connect_to_mqtt_broker: connect_to_mqtt_broker
	disconnect_from_mqtt_broker: disconnect_from_mqtt_broker