public class Otpyrc {
    private static final String ALGO = "AES";
    private static final String CIPHER = "AES/GCM/NoPadding";
    private static final int KEY_SIZE = 128;
    private static final int IV_SIZE = 12; 
    private static final int TAG_SIZE = 128; 
    private static final String BASE64_KEY = "Vn5rHf/xGvW9Vyt3w9TYbg==";

    private static SecretKey getKey() {
        byte[] decodedKey = Base64.getDecoder().decode(BASE64_KEY);
        return new SecretKeySpec(decodedKey, ALGO);
    }

    public static void encryptToFile(String content, Path outputPath) throws Exception {
        byte[] iv = new byte[IV_SIZE];
        SecureRandom random = new SecureRandom();
        random.nextBytes(iv);

        Cipher cipher = Cipher.getInstance(CIPHER);
        GCMParameterSpec gcmSpec = new GCMParameterSpec(TAG_SIZE, iv);
        cipher.init(Cipher.ENCRYPT_MODE, getKey(), gcmSpec);

        byte[] ciphertext = cipher.doFinal(content.getBytes());

        byte[] combined = new byte[iv.length + ciphertext.length];
        System.arraycopy(iv, 0, combined, 0, iv.length);
        System.arraycopy(ciphertext, 0, combined, iv.length, ciphertext.length);

        Files.writeString(outputPath, Base64.getEncoder().encodeToString(combined));
    }

    public static String decryptFromFile(Path inputPath) throws Exception {
        try {
            byte[] combined = Base64.getDecoder().decode(Files.readString(inputPath));
            byte[] iv = new byte[IV_SIZE];
            byte[] ciphertext = new byte[combined.length - IV_SIZE];

            System.arraycopy(combined, 0, iv, 0, IV_SIZE);
            System.arraycopy(combined, IV_SIZE, ciphertext, 0, ciphertext.length);

            Cipher cipher = Cipher.getInstance(CIPHER);
            GCMParameterSpec gcmSpec = new GCMParameterSpec(TAG_SIZE, iv);
            cipher.init(Cipher.DECRYPT_MODE, getKey(), gcmSpec);

            byte[] decrypted = cipher.doFinal(ciphertext);
            return new String(decrypted);
        } catch (Exception e) {
            return Files.readString(inputPath);
        }
    }
}