package com.common.security.pgp;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.util.Date;
import java.util.Iterator;

import org.bouncycastle.bcpg.ArmoredOutputStream;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.PGPCompressedData;
import org.bouncycastle.openpgp.PGPCompressedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedData;
import org.bouncycastle.openpgp.PGPEncryptedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedDataList;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPLiteralData;
import org.bouncycastle.openpgp.PGPLiteralDataGenerator;
import org.bouncycastle.openpgp.PGPObjectFactory;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyEncryptedData;
import org.bouncycastle.openpgp.PGPPublicKeyRing;
import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
import org.bouncycastle.openpgp.PGPSecretKey;
import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
import org.bouncycastle.openpgp.PGPUtil;

/**
 * Simple routine to encrypt and decrypt using a Public and Private key with passphrase. This service
 * routine provides the basic PGP services between byte arrays.
 *
 */
public class PgpEncryption {


    private static PGPPrivateKey findSecretKey(
            PGPSecretKeyRingCollection pgpSec, long keyID, char[] pass)
            throws PGPException, NoSuchProviderException {
        PGPSecretKey pgpSecKey = pgpSec.getSecretKey(keyID);

        if (pgpSecKey == null) {
            return null;
        }

        return pgpSecKey.extractPrivateKey(pass, "BC");
    }

    /**
     * decrypt the passed in message stream
     *
     * @param encrypted
     *            The message to be decrypted.
     * @param passPhrase
     *            Pass phrase (key)
     *
     * @return Clear text as a byte array. I18N considerations are not handled
     *         by this routine
     * @exception IOException
     * @exception PGPException
     * @exception NoSuchProviderException
     */
    public static byte[] decrypt(byte[] encrypted, InputStream keyIn, char[] password)
            throws IOException, PGPException, NoSuchProviderException {
        InputStream in = new ByteArrayInputStream(encrypted);

        in = PGPUtil.getDecoderStream(in);

        PGPObjectFactory pgpF = new PGPObjectFactory(in);
        PGPEncryptedDataList enc = null;
        Object o = pgpF.nextObject();

        //
        // the first object might be a PGP marker packet.
        //
        if (o instanceof PGPEncryptedDataList) {
            enc = (PGPEncryptedDataList) o;
        } else {
            enc = (PGPEncryptedDataList) pgpF.nextObject();
        }



        //
        // find the secret key
        //
        Iterator it = enc.getEncryptedDataObjects();
        PGPPrivateKey sKey = null;
        PGPPublicKeyEncryptedData pbe = null;
        PGPSecretKeyRingCollection pgpSec = new PGPSecretKeyRingCollection(
                PGPUtil.getDecoderStream(keyIn));

        while (sKey == null && it.hasNext()) {
            pbe = (PGPPublicKeyEncryptedData) it.next();

            sKey = findSecretKey(pgpSec, pbe.getKeyID(), password);
        }

        if (sKey == null) {
            throw new IllegalArgumentException(
                    "secret key for message not found.");
        }

        InputStream clear = pbe.getDataStream(sKey, "BC");



        PGPObjectFactory pgpFact = new PGPObjectFactory(clear);

        PGPCompressedData cData = (PGPCompressedData) pgpFact.nextObject();

        pgpFact = new PGPObjectFactory(cData.getDataStream());

        PGPLiteralData ld = (PGPLiteralData) pgpFact.nextObject();

        InputStream unc = ld.getInputStream();

        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int ch;

        while ((ch = unc.read()) >= 0) {
            out.write(ch);

        }

        byte[] returnBytes = out.toByteArray();
        out.close();
        return returnBytes;
    }

    /**
     * Simple PGP encryptor between byte[].
     *
     * @param clearData
     *            The test to be encrypted
     * @param passPhrase
     *            The pass phrase (key). This method assumes that the key is a
     *            simple pass phrase, and does not yet support RSA or more
     *            sophisiticated keying.
     * @param fileName
     *            File name. This is used in the Literal Data Packet (tag 11)
     *            which is really inly important if the data is to be related to
     *            a file to be recovered later. Because this routine does not
     *            know the source of the information, the caller can set
     *            something here for file name use that will be carried. If this
     *            routine is being used to encrypt SOAP MIME bodies, for
     *            example, use the file name from the MIME type, if applicable.
     *            Or anything else appropriate.
     *
     * @param armor
     *
     * @return encrypted data.
     * @exception IOException
     * @exception PGPException
     * @exception NoSuchProviderException
     */
    public static byte[] encrypt(byte[] clearData, PGPPublicKey encKey,
            String fileName,boolean withIntegrityCheck, boolean armor)
            throws IOException, PGPException, NoSuchProviderException {
        if (fileName == null) {
            fileName = PGPLiteralData.CONSOLE;
        }

        ByteArrayOutputStream encOut = new ByteArrayOutputStream();

        OutputStream out = encOut;
        if (armor) {
            out = new ArmoredOutputStream(out);
        }

        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        PGPCompressedDataGenerator comData = new PGPCompressedDataGenerator(
                PGPCompressedDataGenerator.ZIP);
        OutputStream cos = comData.open(bOut); // open it with the final
        // destination
        PGPLiteralDataGenerator lData = new PGPLiteralDataGenerator();

        // we want to generate compressed data. This might be a user option
        // later,
        // in which case we would pass in bOut.
        OutputStream pOut = lData.open(cos, // the compressed output stream
                PGPLiteralData.BINARY, fileName, // "filename" to store
                clearData.length, // length of clear data
                new Date() // current time
                );
        pOut.write(clearData);

        lData.close();
        comData.close();

        PGPEncryptedDataGenerator cPk = new PGPEncryptedDataGenerator(
                PGPEncryptedData.CAST5, withIntegrityCheck, new SecureRandom(),
                "BC");

        cPk.addMethod(encKey);

        byte[] bytes = bOut.toByteArray();

        OutputStream cOut = cPk.open(out, bytes.length);

        cOut.write(bytes); // obtain the actual bytes from the compressed stream

        cOut.close();

        out.close();

        return encOut.toByteArray();
    }

    private static PGPPublicKey readPublicKey(InputStream in)
            throws IOException, PGPException {
        in = PGPUtil.getDecoderStream(in);

        PGPPublicKeyRingCollection pgpPub = new PGPPublicKeyRingCollection(in);

        //
        // we just loop through the collection till we find a key suitable for
        // encryption, in the real
        // world you would probably want to be a bit smarter about this.
        //

        //
        // iterate through the key rings.
        //
        Iterator rIt = pgpPub.getKeyRings();

        while (rIt.hasNext()) {
            PGPPublicKeyRing kRing = (PGPPublicKeyRing) rIt.next();
            Iterator kIt = kRing.getPublicKeys();

            while (kIt.hasNext()) {
                PGPPublicKey k = (PGPPublicKey) kIt.next();

                if (k.isEncryptionKey()) {
                    return k;
                }
            }
        }

        throw new IllegalArgumentException(
                "Can't find encryption key in key ring.");
    }

    public static byte[] getBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);

        // Get the size of the file
        long length = file.length();

        if (length > Integer.MAX_VALUE) {
            // File is too large
        }

        // Create the byte array to hold the data
        byte[] bytes = new byte[(int)length];

        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
               && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }

        // Ensure all the bytes have been read in
        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+file.getName());
        }

        // Close the input stream and return bytes
        is.close();
        return bytes;
    }

    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());


        byte[] original = "Hello world".getBytes();
        System.out.println("Starting PGP test");

        FileInputStream pubKey = new FileInputStream("/Users/me/pub.key");
        byte[] encrypted = encrypt(original, readPublicKey(pubKey), null,
                true, true);

        FileOutputStream dfis = new FileOutputStream("/Users/me/enc.asc");
        dfis.write(encrypted);
        dfis.close();

        byte[] encFromFile = getBytesFromFile(new File("/Users/me/enc.asc"));
        FileInputStream secKey = new FileInputStream("/Users/me/sec.key");

        System.out.println("\nencrypted data = '" + new String(encrypted) + "'");

        byte[] decrypted = decrypt(encFromFile, secKey, "passphrase".toCharArray());

        System.out.println("\ndecrypted data = '" + new String(decrypted) + "'");


    }
}