package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io/fs"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"

	"github.com/go-logr/stdr"
	"go.xsfx.dev/workgroups"
)

var (
	re             = regexp.MustCompile(`\(Teil\s(\d+)\)`)
	ErrWrongNumber = errors.New("wrong submatch number")
)

func main() {
	dir := flag.String("dir", "", "dir to run on")

	flag.Parse()

	if *dir == "" {
		log.Fatal("missing dir")
	}

	files := []string{}

	if err := filepath.WalkDir(*dir, func(path string, d fs.DirEntry, err error) error {
		if !d.IsDir() {
			files = append(files, path)
		}

		return nil
	},
	); err != nil {
		log.Fatal(err)
	}

	log := stdr.New(log.New(os.Stderr, "", log.Lshortfile))

	dis, ctx := workgroups.NewDispatcher(
		context.Background(),
		log.WithName("workgroups"),
		runtime.GOMAXPROCS(0),
		len(files),
	)

	stdr.SetVerbosity(0)

	dis.Start()

	for _, f := range files {
		f := f
		dis.Append(workgroups.NewJob(ctx, func(ctx context.Context) error {
			if tn := re.FindStringSubmatch(f); tn != nil {
				log := log.WithValues("file", f)

				if len(tn) != 2 {
					return ErrWrongNumber
				}
				ti, err := strconv.Atoi(tn[1])
				if err != nil {
					return fmt.Errorf("failed to convert ti to int: %w", err)
				}

				log.Info("extracted tracknumber", "track", ti)

				fixedName := fmt.Sprintf("%s.FIXED.opus", f)

				cmd := exec.CommandContext(
					ctx,
					"ffmpeg",
					"-i",
					f,
					"-metadata",
					fmt.Sprintf("track=%d", ti),
					"-c:a",
					"copy",
					fixedName,
				)

				// cmd.Stdout = os.Stdout
				// cmd.Stderr = os.Stderr

				if err := cmd.Run(); err != nil {
					return fmt.Errorf("error on command: %w", err)
				}

				log.Info("moving fixed to real file", "fixed", fixedName)
				if err := os.Rename(fixedName, f); err != nil {
					return fmt.Errorf("failed to rename: %w", err)
				}
			}

			return nil
		}))
	}

	dis.Close()

	if err := dis.Wait(); err != nil {
		log.Error(err, "error on waiting")
		os.Exit(1)
	}
}