package main

import (
	"fmt"
	"log"
	"os"

	MQTT "github.com/eclipse/paho.mqtt.golang"
	mqtt "github.com/eclipse/paho.mqtt.golang"
)

// listens on topic for messages
func listener(mqMessages chan mqtt.Message) {
	opts := setupMQTT()
	client := MQTT.NewClient(opts)
	topic := "home/rgbboard"
	if token := client.Connect(); token.Wait() && token.Error() != nil {
		log.Println(fmt.Sprintf("failed to connect to mq: %s", token.Error().Error()))
		panic(token.Error())
	}
	log.Println("connected")
	client.Subscribe(topic, 0, func(client mqtt.Client, msg mqtt.Message) {
		log.Println("Receiving ", string(msg.Payload()), " on topic: ", msg.Topic())
		mqMessages <- msg
	})
}

// connection lost management
func onConnectionLostHandler(c MQTT.Client, reason error) {
	log.Fatalf(reason.Error())
}

// setup connection to mqtt, topic to listen to, qos
func setupMQTT() *mqtt.ClientOptions {
	opts := MQTT.NewClientOptions()
	opts.AddBroker(fmt.Sprintf("tcp://%s:%s", os.Getenv("MQTTBROKER"), os.Getenv("MQTTPORT")))
	opts.SetUsername(os.Getenv("MQTTUSER"))
	opts.SetPassword(os.Getenv("MQTTPASSWORD"))
	opts.SetClientID("rgbboard")
	opts.SetAutoReconnect(true)
	opts.SetConnectionLostHandler(onConnectionLostHandler)

	return opts
}