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package in.s8.rsa.utility;


import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.xml.bind.DatatypeConverter;

import in.s8.rsa.constant.S8Constant;
import in.s8.rsa.util.Exponent;
import in.s8.rsa.util.Modulus;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.util.encoders.Hex;

/**
 * RsaClient , decrypt the encrypted String Provide to utility.
 * Created on 4/26/2016.
 *
 * @Author Sourabh_Sethi
 */
public class RsaClient {

    /**
     * Encrypt the plain text using public key.
     *
     * @param text : original plain text
     * @param :The public key
     * @return Encrypted text
     * @throws java.lang.Exception
     */
    public static byte[] encrypt(String text, RSAPublicKey rsaPK) {
        byte[] cipherText = null;
        try {
            // get an RSA cipher object and print the provider
            final Cipher cipher = Cipher.getInstance(S8Constant.ALGORITHM);

            // rsa the plain text using the public key
            cipher.init(Cipher.ENCRYPT_MODE, rsaPK);

            cipherText = cipher.doFinal(text.getBytes());

        } catch (Exception e) {
            e.printStackTrace();
        }
        return cipherText;
    }


    /**
     * Decrypt text using private key.
     *
     * @param text :encrypted text
     * @param key  :The private key
     * @return plain text
     * @throws java.lang.Exception
     */
    public static String decrypt(byte[] text, PrivateKey key) throws NoSuchPaddingException, NoSuchAlgorithmException,
            InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        byte[] dectyptedText = null;

        // get an RSA cipher object and print the provider
        final Cipher cipher = Cipher.getInstance(S8Constant.ALGORITHM);

        // decrypt the text using the private key
        cipher.init(Cipher.DECRYPT_MODE, key);
        dectyptedText = cipher.doFinal(text);

        System.out.print("dectyptedText" + dectyptedText);

        return new String(dectyptedText);
    }


    public static byte[] base64ToHex(String base64Value) {
        byte[] decodedBase64 = Base64.decode(base64Value);
        Hex hex = new Hex();
        return hex.encode(decodedBase64);
    }


    /**
     * Test the EncryptionUtil
     */
    public static void main(String[] args) {

        try {

            ObjectInputStream inputStream = null;

            Exponent exponent = new Exponent();
            Modulus modulus = new Modulus();

            //String encrypedTxt = "0139b8418b8592025c5c973cae3b211824b089ebfa2cf7f022f7ec5354b3431a3b479a3bb30badae37737d93c3dd3a0d64ee37eaac17643edbb556c42eeb2806f33ed7e34cc0da059de6994858ddf3e00c6f50efafe37b8ca18614e07423256c32e1ceee9b668aa3835b3ca6c35710842e8e131fb838fc2f646bf3cdecc89097";
            String encrypedTxt = args[1];

            final String cipherText = encrypedTxt;

            // Decrypt the cipher text using the private key.
            inputStream = new ObjectInputStream(new FileInputStream(S8Constant.PRIVATE_KEY_FILE));
            final PrivateKey privateKey = (PrivateKey) inputStream.readObject();
            System.out.println(privateKey.toString());
            System.out.println(new BigInteger(cipherText, 16));


            inputStream = new ObjectInputStream(new FileInputStream(S8Constant.PUBLIC_KEY_FILE));
            final RSAPublicKey publicKey = (RSAPublicKey) inputStream.readObject();
            final String exp = exponent.getExponent(publicKey);
            final String mod = modulus.getModulus(publicKey);

            System.out.println("====Start====Encrypt=====RSA=====Module======");

            System.out.println("Exponent:- " + exp);
            System.out.println("Modulus:-  " + mod);
            System.out.println("Public Key:-  " + publicKey.toString());

            System.out.println("====End======Encrypt=====RSA=====Module======");


            final String plainText = decrypt(DatatypeConverter.parseHexBinary(cipherText), privateKey);
            System.out.println("Encrypted Text: " + cipherText.toString());
            System.out.println("Decrypted Text: " + plainText);

        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Please pass argument 1 as encrypted text to decrypt");
            System.out.println("Example:-");
            System.out.println("java -cp RSA-Encryption-Decryption-1.0.jar RsaClient Encrypted-String");
            System.out.println("OR");
            System.out.println("java -jar RSA-Encryption-Decryption-1.0.jar RsaClient  Encrypted-String");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


}