package main

import (
	"fmt"
	"hash/crc32"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

func main() {
	regex, _ := regexp.Compile(` \[[A-Z0-9]{8}\]$`)
	files := os.Args[1:]

	for _, name := range files {
		file, err := os.Open(name)
		if err != nil {
			fmt.Printf(`Couldn't open file "%s", exiting ...`, name)
			os.Exit(1)
		}

		ext := filepath.Ext(name)
		basename := name[0 : len(name)-len(ext)]
		if regex.MatchString(basename) {
			basename = basename[0 : len(basename)-11]
		}

		hash := crc32.NewIEEE()

		io.Copy(hash, file)

		err = file.Close()
		if err != nil {
			fmt.Printf(`Couldn't close file "%s", exiting ...`, name)
			os.Exit(1)
		}

		sum := fmt.Sprintf(`%X`, hash.Sum32())
		sum = strings.Repeat(`0`, 8-len(sum)) + sum

		err = os.Rename(name, fmt.Sprintf("%s [%s]%s", basename, sum, ext))
		if err != nil {
			fmt.Printf(`Couldn't rename file "%s", exiting ...`, name)
			os.Exit(1)
		}
	}
}