package org.openslx.satellitedaemon;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPrivateKeySpec;

import org.apache.log4j.Logger;

public class AsymKeyHolder
{
	private static final Logger LOG = Logger.getLogger( AsymKeyHolder.class );
	
	private static PrivateKey privKey = null;
	private static PublicKey pubKey = null;

	/**
	 * Get private key for this server. If none exists yet, create a new one.
	 * 
	 * @return
	 */
	public static PrivateKey getPrivateKey()
	{
		if (privKey == null) {
			if (!loadKey() && !generateKey()) {
				LOG.warn( "Could not load or generate keypair for communication with masterserver" );
			}
		}

		return privKey;
	}

	private static boolean loadKey()
	{
		BufferedReader br = null;
		String modulus, exponent;
		KeyFactory keyFact;

		try {
			keyFact = KeyFactory.getInstance( "RSA" );
		} catch ( NoSuchAlgorithmException nSAE ) {
			LOG.warn( "Could not get a KeyFactory to load the key from disk", nSAE );
			return false;
		}

		try {
			br = new BufferedReader( new FileReader( "config/private.key" ) );
			modulus = br.readLine();
			exponent = br.readLine();
		} catch ( FileNotFoundException e ) {
			LOG.error( "File 'private.key' not found!", e );
			return false;
		} catch ( IOException e ) {
			LOG.error( "File 'private.key' not correct readable.", e );
			return false;
		} finally {
			try {
				br.close();
			} catch ( IOException e ) {
			}
		}
		if ( modulus == null || exponent == null ) {
			return false;
		}

		try {
			BigInteger mod = new BigInteger( modulus );
			BigInteger exp = new BigInteger( exponent );

			RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec( mod, exp );
			synchronized ( keyFact ) {
				privKey = keyFact.generatePrivate( keySpec );
			}
			return privKey != null;
		} catch ( InvalidKeySpecException e ) {
			LOG.error( "Not able to build key with given numbers.", e );
		} catch ( NumberFormatException e ) {
			LOG.error( "Invalid number format.", e );
		}
		return false;
	}
	
	private static boolean generateKey()
	{
		//		KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
		//		kpg.initialize(4096);
		//		KeyPair kp = kpg.generateKeyPair();
		//		RSAPrivateKey privateKey = (RSAPrivateKey) kp.getPrivate();
		//		RSAPublicKey publicKey = (RSAPublicKey) kp.getPublic();
		//		
		//		log.debug("modulus: " + privateKey.getModulus().toString());
		//		log.debug("exponent: " + privateKey.getPrivateExponent().toString());
		//		
		//		
		//		log.debug("modulus: " + publicKey.getModulus().toString());
		//		log.debug("exponent: " + publicKey.getPublicExponent().toString());
		//		
		//		System.exit(1);
		return true;
	}

}