package main

import (
	"encoding/json"
	"flag"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"strings"

	"github.com/rumblefrog/go-a2s"
)

type apiResponse struct {
	Response struct {
		Success           bool   `json:"success"`
		UpToDate          bool   `json:"up_to_date"`
		VersionIsListable bool   `json:"version_is_listable"`
		RequiredVersion   int    `json:"require_version"`
		Message           string `json:"message"`
	} `json:"response"`
}

func main() {
	// Steam API takes version to check if newer version is available
	url := "https://api.steampowered.com/ISteamApps/UpToDateCheck/v1/?appid=440&version="

	var ip string
	var port int
	var name string
	var command string

	// Defining Flags
	flag.StringVar(&ip, "ip", "127.0.0.1", "Specify ip to use.")
	flag.IntVar(&port, "port", 27015, "Specify port to use.")
	flag.StringVar(&name, "name", "Server", "Specify Server Name to use in the Webhook.")
	flag.StringVar(&command, "command", "", "Specify Command to run if the Server is not on the newest Version.")
	flag.Parse()

	// Creating A2S Request to Server
	client, err := a2s.NewClient(ip + ":" + strconv.FormatUint(uint64(port), 10))
	if err != nil {
		log.Fatal("Creation of client failed: %w", err)
		return
	}

	defer client.Close()

	info, err := client.QueryInfo()

	// Checking if we received an error while peforming A2S request
	if err != nil {
		if strings.HasSuffix(err.Error(), "connection refused") {
			log.Fatal("Server refused connection.")
		}
		log.Fatal("Querying failed: %s", err)
	}

	log.Printf("Current Server Version: %s", info.Version)

	// Creating httpClient and sending Request to Steam API
	httpClient := http.Client{}

	req, err := http.NewRequest(http.MethodGet, url+info.Version, nil)
	if err != nil {
		log.Fatal(err)
	}

	res, err := httpClient.Do(req)
	if err != nil {
		log.Fatal(err)
	}

	if res.Body != nil {
		defer res.Body.Close()
	}

	body, err := io.ReadAll(res.Body)
	if err != nil {
		log.Fatal(err)
	}

	response := apiResponse{}

	err = json.Unmarshal(body, &response)
	if err != nil {
		log.Fatal(err)
	}

	// Checking if Server is on the newest Server version, if false execute Command given by the user
	if response.Response.UpToDate {
		log.Printf("Server is already on newest version.")
	} else {
		log.Printf("Server needs to be updated, executing command %s", command)
		cmd := exec.Command("bash", "-c", command)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr

		err := cmd.Run()

		if err != nil {
			log.Fatal(err)
		}
	}
}