package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"
	"text/template"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

type serverSettings struct {
	port                                  int
	jsonPort                              int
	plexAddr                              string
	plexToken                             string
	plexTimeout                           int
	metricsPrefix                         string
	metricsMediaCollectingIntervalSeconds int
}

func envGetter(key, fallback string) string {
	if value, ok := os.LookupEnv(key); ok {
		return value
	}
	return fallback
}

func setupServerSettings() serverSettings {
	port, err := strconv.Atoi(envGetter("PORT", "9545"))
	if err != nil {
		log.Fatal("Unable to parse port string to int, failing....")
	}
	jsonPort, err := strconv.Atoi(envGetter("JSONPORT", "9546"))
	if err != nil {
		log.Fatal("Unable to parse jsonapi port string to int, failing....")
	}
	plexToken, value := os.LookupEnv("PLEX_TOKEN")
	if !value {
		log.Fatal("No plex token provided, failing....")
	}
	plexTimeout, err := strconv.Atoi(envGetter("PLEX_TIMEOUT", "10"))
	if err != nil {
		log.Fatal("Unable to parse plextimeout string to int, failing....")
	}
	metricsMediaCollectingIntervalSeconds, err := strconv.Atoi(envGetter("METRICS_MEDIA_COLLECTING_INTERVAL_SECONDS", "300"))
	if err != nil {
		log.Fatal("Unable to parse METRICS_MEDIA_COLLECTING_INTERVAL_SECONDS string to int, failing....")
	}

	return serverSettings{
		port:                                  port,
		jsonPort:                              jsonPort,
		plexAddr:                              envGetter("PLEX_ADDR", "http://localhost:32400"),
		plexToken:                             plexToken,
		plexTimeout:                           plexTimeout,
		metricsPrefix:                         envGetter("METRICS_PREFIX", "PLEX"),
		metricsMediaCollectingIntervalSeconds: metricsMediaCollectingIntervalSeconds,
	}
}

func setupJSONAPI(plexStatsChannel chan *plexStats, settings serverSettings) {

	// Create a new router
	mux := http.NewServeMux()

	tmpl := template.Must(template.ParseFiles("homepage.html"))

	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		tmpl.Execute(w, nil)
	})

	// Create a handler for the `/plex-stats` endpoint
	mux.HandleFunc("/plex-stats", func(w http.ResponseWriter, r *http.Request) {
		// Create a new plexStats struct
		plexStats := <-plexStatsChannel

		// Marshal the plexStats struct to JSON
		jsonBody, err := json.Marshal(plexStats)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		// Set the content type to JSON
		w.Header().Set("Content-Type", "application/json")

		// Write the JSON body to the response
		w.Write(jsonBody)
	})

	// Start the server
	fmt.Println("Starting JSON API Server.....")
	http.ListenAndServe(fmt.Sprintf(":%d", settings.jsonPort), mux)

}

func setStats(stats *plexStats) {
	plexActiveSessions.Set(stats.CurrentSessions)
	plexNumMovies.Set(stats.NumMovies)
	plexNumTVShows.Set(stats.NumTV)
	plexTranscodeSessions.Set(stats.NumTranscodes)
	plexAllSessions.Set(stats.NumAllSessions)
}

func main() {

	os.Setenv("PORT", "9545")
	os.Setenv("JSONPORT", "9546")
	os.Setenv("PLEX_ADDR", "https://plex.derajnet.duckdns.org:32400")
	os.Setenv("PLEX_TOKEN", "5ezJu5cjnhoAbPJRKngs")
	os.Setenv("PLEX_TIMEOUT", "10")
	os.Setenv("METRICS_PREFIX", "PLEX")
	os.Setenv("METRICS_MEDIA_COLLECTING_INTERVAL_SECONDS", "300")

	settings := setupServerSettings()
	// Setup plex client
	pc := setupClient(&settings)
	// Our initial gather to ensure we don't send zeros to prometheus
	stats := pc.gatherAllStats()
	setStats(stats)
	// Creating a data sharing channel to send same data to our json api server
	plexStatsChannel := make(chan *plexStats)
	go setupJSONAPI(plexStatsChannel, settings)

	go func() {
		for {
			time.Sleep(time.Second * 5)
			fmt.Println("Collecting info...")
			stats := pc.gatherAllStats()
			setStats(stats)
			// Kind of an ugly workaround?
			//Will cause some travel times to be up to 5 seconds as the channel in the mux waits for data to be populated?
			select {
			case plexStatsChannel <- stats:
			default:
			}

		}
	}()

	prometheus.MustRegister(plexActiveSessions)
	prometheus.MustRegister(plexNumMovies)
	prometheus.MustRegister(plexNumTVShows)
	prometheus.MustRegister(plexTranscodeSessions)
	prometheus.MustRegister(plexAllSessions)

	// m := NewMetrics(reg)
	fmt.Println("Startup of promethus handler complete...")
	http.Handle("/metrics", promhttp.Handler())
	err := http.ListenAndServe(fmt.Sprintf(":%d", settings.port), nil)
	if err != nil {
		log.Fatal("Unable to start the prometheus handler....")
	}

}