package utils

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"fmt"
	"io"
)

var SKey []byte

func EncryptData(data []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}

	nonce := make([]byte, gcm.NonceSize())
	_, err = io.ReadFull(rand.Reader, nonce)
	if err != nil {
		return nil, err
	}
	ciphertext := gcm.Seal(nonce, nonce, data, nil)

	return ciphertext, nil
}

func DecryptData(data []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}

	nonceSize := gcm.NonceSize()
	if len(data) < nonceSize {
		return nil, fmt.Errorf("ciphertext too short")
	}

	nonce, ciphertext := data[:nonceSize], data[nonceSize:]

	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return nil, err
	}
	return plaintext, nil
}