package main

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"github.com/BurntSushi/toml"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

const (
	manifestUrl   = "https://updater.project-epoch.net/api/manifest"
	configDirName = "epoch-linux"
	configName    = "config.toml"
)

type Config struct {
	WowDir string
}

var (
	config Config
)

func setupConfig() {
	home := os.Getenv("HOME")
	if home == "" {
		log.Fatal("$HOME environment variable not set")
	}

	cfgPath := filepath.Join(home, ".config", configDirName, configName)

	if _, statErr := os.Stat(cfgPath); os.IsNotExist(statErr) {
		os.MkdirAll(filepath.Join(home, ".config", configDirName), 0755)

		newConfig := &Config{
			WowDir: "/path/to/wow",
		}

		file, err := os.Create(cfgPath)
		if err != nil {
			log.Fatal(err)
		}
		defer file.Close()

		encoder := toml.NewEncoder(file)
		if err = encoder.Encode(newConfig); err != nil {
			log.Fatal(err)
		}

		fmt.Printf("Created new config at %s, edit it before running the launcher again\n", cfgPath)
		os.Exit(0)
	}

	_, err := toml.DecodeFile(cfgPath, &config)
	if err != nil {
		log.Fatal(err)
	}
}

func main() {
	setupConfig()

	count, err := downloadUpdate()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("Updated %d files\n", count)
}

func downloadUpdate() (int, error) {
	var c int

	manifest, err := getManifest()
	if err != nil {
		log.Fatalf("Failed to get manifest: %v\n", err)
	}

	for _, file := range manifest.Files {
		path := strings.ReplaceAll(file.Path, `\`, `/`)
		path = strings.TrimLeft(path, `\`)

		localPath := filepath.Join(config.WowDir, path)
		localDir := filepath.Dir(localPath)
		if _, err = os.Stat(localDir); os.IsNotExist(err) {
			os.MkdirAll(localDir, 0755)
		}

		if _, err = os.Stat(localPath); err == nil {
			data, err := os.ReadFile(localPath)
			if err != nil {
				return c, err
			}
			hashBytes := md5.Sum(data)
			hash := hex.EncodeToString(hashBytes[:])
			if hash == file.Hash {
				continue
			}
		}

		fmt.Printf("Updating %s...\n", file.Path)

		outFile, err := os.Create(localPath)
		if err != nil {
			return c, err
		}
		defer outFile.Close()

		resp, err := http.Get(file.URL)
		if err != nil {
			return c, err
		}
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return c, fmt.Errorf("failed to download update from %s, status code: %d", file.URL, resp.StatusCode)
		}

		_, err = io.Copy(outFile, resp.Body)
		if err != nil {
			return c, err
		}

		c += 1
	}

	return c, nil
}