package main

import (
	"log"
	"net/http"
	"os"
	"flag"
	"github.com/eclipse/paho.mqtt.golang"
	"github.com/hikhvar/mqtt2prometheus/pkg/metrics"
	"github.com/hikhvar/mqtt2prometheus/pkg/mqttclient"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"fmt"
	"github.com/hikhvar/mqtt2prometheus/pkg/config"
)

var (
	configFlag = flag.String(
		"config",
		"config.yaml",
		"config file",
	)
	portFlag = flag.String(
		"listen-port",
		"9641",
		"HTTP port used to expose metrics",
	)
	addressFlag = flag.String(
		"listen-address",
		"0.0.0.0",
		"listen address for HTTP server used to expose metrics",
	)
)

func main() {
	flag.Parse()
	c := make(chan os.Signal, 1)
	hostName, err := os.Hostname()
	if err != nil {
		log.Fatalf("Could not get hostname. %s\n", err.Error())
	}
	cfg, err := config.LoadConfig(*configFlag)
	if err != nil {
		log.Fatalf("Could not load config: %s\n", err.Error())
	}
	mqttClientOptions := mqtt.NewClientOptions()
	mqttClientOptions.AddBroker(cfg.MQTT.Server).SetClientID(hostName).SetCleanSession(true)
	mqttClientOptions.SetUsername(cfg.MQTT.User)
	mqttClientOptions.SetPassword(cfg.MQTT.Password)

	collector := metrics.NewCollector(cfg.Cache.Timeout, cfg.Metrics)
	ingest := metrics.NewIngest(collector, cfg.Metrics)

	errorChan := make(chan error,1)

	err = mqttclient.Subscribe(mqttClientOptions, mqttclient.SubscribeOptions{
		Topic:             cfg.MQTT.TopicPath + "/+",
		QoS:               cfg.MQTT.QoS,
		OnMessageReceived: ingest.SetupSubscriptionHandler(errorChan),
	})
	if err != nil {
		log.Fatalf("Could not connect to mqtt broker %s", err.Error())
	}
	prometheus.MustRegister(ingest.MessageMetric)
	prometheus.MustRegister(collector)
	http.Handle("/metrics", promhttp.Handler())
	go func() {
		err = http.ListenAndServe(getListenAddress(), nil)
		if err != nil {
			log.Fatalf("Error while serving http: %s", err.Error())
		}
	}()

	for {
		select {
		case <-c:
			log.Println("Terminated via Signal. Stop.")
			os.Exit(0)
		case err = <-errorChan:
			log.Printf("Error while processing message. %s", err.Error())
		}
	}
}

func getListenAddress() string {
	return fmt.Sprintf("%s:%s", *addressFlag, *portFlag)
}