package main

import (
	"crypto/tls"
	_ "embed"
	"encoding/json"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"

	"github.com/dreamscached/minequery/v2"
	"golang.org/x/crypto/acme/autocert"
)

type config struct {
	Title       string        `json:"title"`
	Content     template.HTML `json:"content"`
	Servers     []server      `json:"servers"`
	UseTLS      bool          `json:"useTLS"`
	TLSHostname string        `json:"tlshostname"`
	ServerPort  int           `json:"serverport"`
	BackupDir   string        `json:"backupDir"`
}

type server struct {
	Host   string `json:"host"`
	Port   int    `json:"port"`
	Status *minequery.Status17
}

type pageData struct {
	Title   string
	Content template.HTML
	Servers []server
}

//go:embed index.html
var indexhtml string

func main() {

	// Parse config file
	configData, err := os.ReadFile("./config.json")
	if err != nil {
		log.Fatalf("Error reading config file: %v\n", err)
	}

	var config config

	err = json.Unmarshal(configData, &config)
	if err != nil {
		log.Fatalf("Error parsing config file: %v\n", err)
	}

	serveBackups := true
	if stat, err := os.Stat(config.BackupDir); os.IsNotExist(err) || !stat.IsDir() {
		log.Printf("Backup directory %v does not exist; not serving backups.", config.BackupDir)
		serveBackups = false
	}

	data := pageData{}
	data.Title = config.Title
	data.Content = config.Content
	data.Servers = config.Servers

	// Set up templates
	fmt.Print("Parsing templates...\n")
	t, err := template.New("").Parse(indexhtml)
	if err != nil {
		log.Fatalf("Error parsing HTML template: %v\n", err)
	}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

		// Update servers with current data
		for i, s := range config.Servers {
			// TODO: Query instead (opportunistically?) to get mod lists, etc
			config.Servers[i].Status, err = minequery.Ping17(s.Host, s.Port)
			if err != nil {
				log.Printf("Error querying server: %v", err)
			}
		}

		err = t.Execute(w, data)
		if err != nil {
			log.Printf("Error executing template: %v\n", err)
		}
	})

	// Serve backup directory
	if serveBackups { // TODO: add HTML
		http.Handle("/backups/", http.StripPrefix("/backups/", http.FileServer(http.Dir(config.BackupDir))))
	}

	if config.UseTLS {

		certManager := autocert.Manager{
			Prompt:     autocert.AcceptTOS,
			HostPolicy: autocert.HostWhitelist(config.TLSHostname),
			Cache:      autocert.DirCache("certs"),
		}

		srv := &http.Server{
			Addr: ":https",
			TLSConfig: &tls.Config{
				GetCertificate: certManager.GetCertificate,
			},
		}

		go http.ListenAndServe(":http", certManager.HTTPHandler(nil)) // Handler for LetsEncrypt

		if config.ServerPort == 0 { // Value not set in JSON
			config.ServerPort = 443
		}
		fmt.Printf("Serving HTTPS on port %v...\n", config.ServerPort)
		srv.ListenAndServeTLS("", "") // Key/cert come from srv.TLSConfig

	} else {
		if config.ServerPort == 0 { // Value not set in JSON
			config.ServerPort = 80
		}
		fmt.Printf("Serving HTTP on port %v...\n", config.ServerPort)
		http.ListenAndServe(fmt.Sprintf(":%v", config.ServerPort), nil)
	}

}