import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class Coder {
    public static String encrypt(String clearText, Key key) {
        String result = "";
        try {
            result = tryEncrypt(clearText, key);
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Hiba! Nincs ilyen algoritmus!");
        }catch(NoSuchPaddingException e) {
            System.err.println("Hiba! Nincs ilyen kitöltő!");
        }catch(InvalidKeyException e) {
            System.err.println("Hiba! Érvénytelen kulcs!");
        }catch(UnsupportedEncodingException e) {
            System.err.println("Hiba! Nem támogatott kódolás!");
        }catch(IllegalBlockSizeException e) {
            System.out.println("Hiba! Illegális blokkméret!");
        }catch(BadPaddingException e) {
            System.err.println("Hiba! Rossz kitöltő!");
        }
        return result;
    }

    public static String tryEncrypt(String clearText, Key key) 
            throws 
                NoSuchAlgorithmException, 
                NoSuchPaddingException, 
                InvalidKeyException, 
                UnsupportedEncodingException, 
                IllegalBlockSizeException, 
                BadPaddingException {
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] plainTextByteArray = clearText.getBytes("UTF-8");
        byte[] secretTextByteArray = cipher.doFinal(plainTextByteArray);
        String secretText = new String(Base64.getEncoder().encode(secretTextByteArray));
        return secretText;
    }    

    public static String decrypt(String secretText, Key key) {
        String result = "";
        try {
            result = tryDecrypt(secretText, key);
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Hiba! Nincs ilyen algoritmus!");
        }catch(NoSuchPaddingException e) {
            System.err.println("Hiba! Nincs ilyen kitöltő!");
        }catch(InvalidKeyException e) {
            System.err.println("Hiba! Érvénytelen kulcs!");
        }catch(UnsupportedEncodingException e) {
            System.err.println("Hiba! Nem támogatott kódolás!");
        }catch(IllegalBlockSizeException e) {
            System.out.println("Hiba! Illegális blokkméret!");
        }catch(BadPaddingException e) {
            System.err.println("Hiba! Rossz kitöltő!");
        }
        return result;
    }    
    public static String tryDecrypt(String secretText, Key key) 
            throws 
                NoSuchAlgorithmException, 
                NoSuchPaddingException, 
                InvalidKeyException, 
                UnsupportedEncodingException, 
                IllegalBlockSizeException, 
                BadPaddingException {
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] encryptedByteArray = Base64.getDecoder().decode(secretText);
        byte[] decryptedByteArray = cipher.doFinal(encryptedByteArray);
        String clearText = new String(decryptedByteArray, "UTF-8");
        return clearText;
    }

    public static SecretKeySpec generateKey() throws NoSuchAlgorithmException {
        SecretKeySpec key;
        String algoritmus = "AES";
        int kulcsmeret = 128;
        KeyGenerator keyGenerator = KeyGenerator.getInstance(algoritmus);
        keyGenerator.init(kulcsmeret);
        SecretKey secretKey = keyGenerator.generateKey();
        byte[] raw = secretKey.getEncoded();
        key = new SecretKeySpec(raw, algoritmus);
        return key;
    }
    
}