package Encryption

import (
	"bytes"
  "crypto/aes"
	"errors"
	"os"
	"os/exec"
	"io/ioutil"
  "io"
)

func EditEncryptedFile(password string, FilePath string) (error) {
  var (
    editor string
    tmpFilePath string
    ciphertext []byte
    plaintext []byte
    tmpFile *os.File
    encryptedFile *os.File
    cmd *exec.Cmd
    e error
  )
  editor = os.Getenv("EDITOR")
  if editor == "" {
    return errors.New("EDITOR variable cannot be blank")
  }

	tmpFilePath = os.Getenv("TMPDIR")
  if tmpFilePath == "" {
    tmpFilePath = "/tmp"
  }

	ciphertext, e = ioutil.ReadFile(FilePath)
	if e != nil {
		return e
	}
	if len(ciphertext) < aes.BlockSize {
		return errors.New("ciphertext too short")
	}

	plaintext, e = DecryptData(password, ciphertext)
	if e != nil {
		return e
	}

	tmpFile, e = ioutil.TempFile(tmpFilePath, "")
	if e != nil {
		return e
	}
	_, e = io.Copy(tmpFile, bytes.NewReader(plaintext))
	if e != nil {
		return e
	}

  e = tmpFile.Close()
  if e != nil {
    return e
  }

  cmd = exec.Command(editor, tmpFile.Name())
  cmd.Stdout = os.Stdout
  cmd.Stdin = os.Stdin
  cmd.Stderr = os.Stderr
  e = cmd.Run()
  if (e != nil) {
    return e
  }

	plaintext, e = ioutil.ReadFile(tmpFile.Name())
	if e != nil {
		return e
	}

	ciphertext, e = EncryptData(password, plaintext)
	if e != nil {
		return e
	}
	// open output file
	encryptedFile, e = os.OpenFile(FilePath, os.O_RDWR, 0666)
	if e != nil {
		return e
	}

	defer func() {
		encryptedFile.Close()
		SecureDelete(tmpFile.Name())
	}()

	_, e = io.Copy(encryptedFile, bytes.NewReader(ciphertext))
	if e != nil {
		return e
	}

  return nil
}