package utils

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"errors"
	"io"

	"golang.org/x/crypto/bcrypt"
)

// HashPassword membuat hash dari password plain text
func HashPassword(password string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
	return string(bytes), err
}

// CheckPasswordHash membandingkan password plain text dengan hash
func CheckPasswordHash(password, hash string) bool {
	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
	return err == nil
}

// EncryptAES256 encrypts payload using AES-256-GCM
// key parameter must be 32 bytes
func EncryptAES256(plaintext []byte, key []byte) (string, error) {
	if len(key) != 32 {
		return "", errors.New("AES-256 requires a 32-byte key")
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		return "", err
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}
	nonce := make([]byte, gcm.NonceSize())
	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
		return "", err
	}
	ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
	return base64.StdEncoding.EncodeToString(ciphertext), nil
}

// DecryptAES256 decrypts payload using AES-256-GCM
func DecryptAES256(cryptoText string, key []byte) ([]byte, error) {
	if len(key) != 32 {
		return nil, errors.New("AES-256 requires a 32-byte key")
	}
	ciphertext, err := base64.StdEncoding.DecodeString(cryptoText)
	if err != nil {
		return nil, err
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}
	if len(ciphertext) < gcm.NonceSize() {
		return nil, errors.New("malformed ciphertext")
	}
	nonce, ciphertext := ciphertext[:gcm.NonceSize()], ciphertext[gcm.NonceSize():]
	return gcm.Open(nil, nonce, ciphertext, nil)
}