package main

import (
	"crypto/md5"
	"encoding/hex"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
)

const (
	manifestUrl      = "https://updater.project-epoch.net/api/manifest"
	defaultWowPath   = "/path/to/wow"
	defaultLaunchCmd = "not configured"
)

func main() {
	var (
		helpFlag       bool
		updateOnlyFlag bool
		forceFlag      bool
		rerunConfig    bool
	)
	flag.BoolVar(&helpFlag, "h", false, "Print help")
	flag.BoolVar(&forceFlag, "f", false, "Forces epochcli to update files even if they match the current version")
	flag.BoolVar(&updateOnlyFlag, "u", false, "Ignore EnableLauncher setting in config and only runs an update. Does nothing if EnableLauncher is false")
	flag.BoolVar(&rerunConfig, "c", false, "Runs config configuration step. Overrides the config file")
	flag.Parse()

	if helpFlag {
		flag.CommandLine.SetOutput(os.Stdout)
		fmt.Println("Epochcli Help:")
		flag.PrintDefaults()
		os.Exit(0)
	}

	config, err := setupConfig(rerunConfig)
	if err != nil {
		log.Fatal(err)
	}

	if config.WowDir == defaultWowPath {
		log.Fatalf("WowDir in %s is still the default setting, exiting", cfgPath)
	}

	stats, err := downloadUpdate(config, forceFlag)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%d files updated\n", stats.updated)
	if stats.current > 0 {
		fmt.Printf("%d files are already up to date\n", stats.current)
	}

	if updateOnlyFlag {
		os.Exit(0)
	}

	if config.EnableLauncher {
		if config.LaunchCmd == defaultLaunchCmd {
			log.Fatalf("LaunchCmd in %s is still the default setting, exiting\n", cfgPath)
		}

		fmt.Println("Starting Epoch...")
		if runtime.GOOS == "darwin" {
			exec.Command("open", config.LaunchCmd).Run()
		} else {
			exec.Command(config.LaunchCmd).Run()
		}
	}
}

type DownloadStats struct {
	updated int
	current int
}

func downloadUpdate(config *Config, force bool) (DownloadStats, error) {
	var stats DownloadStats

	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 !force {
			if _, err = os.Stat(localPath); err == nil {
				data, err := os.ReadFile(localPath)
				if err != nil {
					return stats, err
				}
				hashBytes := md5.Sum(data)
				hash := hex.EncodeToString(hashBytes[:])
				if hash == file.Hash {
					fmt.Printf("File %s is up to date\n", localPath)
					stats.current += 1
					continue
				}
			}
		}

		fmt.Printf(" %s...\n", localPath)

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

		resp, err := http.Get(file.URL)
		if err != nil {
			return stats, err
		}
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return stats, 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 stats, err
		}

		stats.updated += 1
	}

	return stats, nil
}