package main

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"runtime"

	flag "github.com/spf13/pflag"
)

var driveLetter string
var report string

func init() {
	flag.StringVarP(&report, "report", "r", "", "json formatted report file.")
}

func main() {
	log.Println("starting GoHash")
	flag.Parse()

	index := make(map[string][]string)
	data, err := ioutil.ReadFile(report)
	if err != nil {
		fmt.Print(err)
	}

	err = json.Unmarshal(data, &index)
	if err != nil {
		fmt.Print(err)
	}

	log.Printf("found %d entries to check.", len(index))

	myFolder := flag.Arg(0)
	file, err := os.Stat(myFolder)
	if os.IsNotExist(err) {
		log.Fatalln("File does not exists:", myFolder)
	}
	if file.IsDir() {
		log.Println("start with folder:", myFolder)
		driveLetter = ""
		if runtime.GOOS == "windows" {
			driveLetter = filepath.VolumeName(myFolder) + "/"
		}
		log.Printf("driveletter: %s", driveLetter)
		doSomething()
	} else {
		log.Printf("file %s has hash %s\n", myFolder, getSha256Hash(myFolder))
	}

	log.Println("done")
}

func doSomething() {

}

func getSha256Hash(fileStr string) string {
	f, err := os.Open(fileStr)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		log.Fatal(err)
	}
	return hex.EncodeToString(h.Sum(nil))
}