convert_mp3.go

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"strings"
)

func main() {
	givenArg := flag.String("a", "", "File|Directory to be converted")
	toDel := flag.Bool("d", false, "To delete the file?")
	flag.Parse()

	if *givenArg == "" {
		flag.PrintDefaults()
		os.Exit(1)
	}

	if _, err := os.Stat(*givenArg); os.IsNotExist(err) {
		fmt.Printf("ERROR: given file (%s) does not exist\n", *givenArg)
		os.Exit(1)
	}

	err := convert(*givenArg, *toDel)
	if err != nil {
		fmt.Printf("ERROR: Convert failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("Conversion done")
	return
}

func convert(givenArg string, toDel bool) error {
	isDir, err := isDirectory(givenArg)
	if err != nil {
		return fmt.Errorf("is directory error: %v", err)
	}
	if isDir {
		files, err := ioutil.ReadDir(givenArg)
		if err != nil {
			return fmt.Errorf("couldn't read dir: %v", err)
		}
		for _, file := range files {
			if givenArg[len(givenArg)-1:] != "/" {
				givenArg = givenArg + "/"
			}
			err := workon(givenArg+file.Name(), toDel)
			if err != nil {
				return fmt.Errorf("workon: %v", err)
			}
		}
	} else {
		err := workon(givenArg, toDel)
		if err != nil {
			return fmt.Errorf("workon: %v", err)
		}
	}
	return nil
}

func isDirectory(path string) (bool, error) {
	fileInfo, err := os.Stat(path)
	return fileInfo.IsDir(), err
}

func workon(given string, del bool) error {
	var allowedExts = []string{"mp4", "mkv", "flv", "avi"}
	var sl = strings.Split(given, ".")
	var ext = sl[len(sl)-1]
	var finalName = strings.Join(sl[:len(sl)-1], ".") + ".mp3"
	if _, err := os.Stat(finalName); !os.IsNotExist(err) {
		fmt.Printf("EXISTS: %s\n", finalName)
		if del {
			err := remove(given)
			if err != nil {
				return fmt.Errorf("remove error: %s", given)
			}
		}
	} else if inSlice(strings.ToLower(ext), allowedExts) {
		fmt.Printf("CONVERT: %s\n", given)
		cmd := fmt.Sprintf("ffmpeg -i '%s' -vn -ar 44100 -ac 2 -ab 192k -f mp3 '%s'", given, finalName)
		output, err := exec.Command(cmd).CombinedOutput()
		if err != nil {
			// os.Stderr.WriteString(err.Error())
			return fmt.Errorf("exec error: %v", err)
		}
		fmt.Println(string(output))
	} else {
		return fmt.Errorf("extension unknown: %v", err)
	}
	return nil
}

func remove(path string) error {
	err := os.Remove(path)
	if err != nil {
		return fmt.Errorf("os remove: %v", err)
	}
	return nil
}

func inSlice(a string, list []string) bool {
	for _, b := range list {
		if b == a {
			return true
		}
	}
	return false
}

func shellQuote(file string) string {
	var replacer = strings.NewReplacer(
		` `, `\ `, `(`, `\(`, `)`, `\)`, `&`, `\&`,
	)
	return replacer.Replace(file)
	// return "'" + replacer.Replace(file) + "'"
}