package main

import (
	"flag"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
)

var dryrun bool
var execCmd string

func main() {
	flag.BoolVar(&dryrun, "n", false, "Show what would have been done.")
	force := flag.Bool("force", false, "Actually rename files.")
	flag.StringVar(&execCmd, "exec", "", "Run command on matching file.")
	path := flag.String("path", ".", "Handle files in path.")
	flag.Parse()

	if flag.NArg() == 0 {
		fmt.Println("No action specified")
		return
	}

	if !dryrun && !*force {
		panic("please dry run first or use the force flag to actually rename files")
	}

	switch flag.Arg(0) {
	case "normalize":
		err := filepath.WalkDir(*path, normalize)
		if err != nil {
			panic(err)
		}
	case "removesuffix":
		suffix := flag.Arg(1)
		err := filepath.Walk(*path, removeSuffix(suffix))
		if err != nil {
			panic(err)
		}
		removeSuffix(suffix)
	case "unpack":
		err := filepath.Walk(*path, unpack)
		if err != nil {
			panic(err)
		}
	default:
		fmt.Println("Invalid action specified")
		return
	}
}

func skipDir(filename string) (bool, error) {
	if filename == "." || filename == ".." {
		return true, nil
	}

	if filename == "Bin" {
		return true, filepath.SkipDir
	}

	return false, nil
}

func removeSuffix(suffix string) filepath.WalkFunc {
	return func(p string, f os.FileInfo, err error) error {
		filename := f.Name()
		if skip, err := skipDir(filename); skip {
			return err
		}

		element := newMediaElement(p)
		fmt.Println(element.Path())

		dir := filepath.Dir(p)
		ext := filepath.Ext(filename)
		filenameNoExt := strings.TrimSuffix(filename, ext)
		filenameNoSuff := strings.TrimSuffix(filenameNoExt, suffix)
		if filenameNoSuff != filenameNoExt {
			newFilename := filenameNoSuff + ext

			err := rename(filepath.Join(dir, filename), filepath.Join(dir, newFilename), dryrun)
			if err != nil {
				fmt.Printf("Could not rename %s: %v\n", filename, err)
			}
		}

		return nil
	}
}

func normalize(p string, f os.DirEntry, err error) error {
	if f == nil || f.IsDir() {
		return nil
	}

	filename := f.Name()
	if skip, err := skipDir(filename); skip {
		return err
	}

	element := newMediaElement(p)
	newPath := element.Path()
	if newPath == p {
		return nil
	}

	return rename(p, newPath, dryrun)
}

func rename(oldPath, newPath string, dryrun bool) error {
	fmt.Printf("\nfrom: %s\nto:   %s\n", oldPath, newPath)
	if dryrun {
		return nil
	}

	return os.Rename(oldPath, newPath)
}

func unpack(p string, f os.FileInfo, err error) error {
	filename := f.Name()
	if skip, err := skipDir(filename); skip {
		return err
	}

	ext := filepath.Ext(filename)
	ext = strings.ToLower(ext)
	if ext != ".rar" {
		return nil
	}

	cmd := exec.Command(execCmd, p)
	filename = strings.TrimSuffix(filename, ext)
	ext = filepath.Ext(filename)
	if ext == "" {
		err := cmd.Run()
		if err != nil {
			fmt.Printf("Error executing: %v\n", err)
		}
		return nil
	}

	if strings.HasPrefix(ext, ".part") {
		ext = ext[5:]
		part, err := strconv.Atoi(ext)
		if err == nil && part == 1 {
			err := cmd.Run()
			if err != nil {
				fmt.Printf("Error executing: %v\n", err)
			}
			return nil
		}
	}
	return nil
}