/*
 * Copyright 2012, 2013 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.common.ssl;

import java.io.File;
import java.security.GeneralSecurityException;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;

import com.redhat.thermostat.common.config.InvalidConfigurationException;
import com.redhat.thermostat.common.internal.KeyStoreProvider;
import com.redhat.thermostat.common.internal.TrustManagerFactory;
import com.redhat.thermostat.common.utils.LoggingUtils;

public class SSLContextFactory {

    private static final Logger logger = LoggingUtils.getLogger(SSLContextFactory.class);
    private static final String PROTOCOL = "TLS";
    private static final String ALGORITHM = "SunX509";
    private static SSLContext serverContext;
    private static SSLContext clientContext;
    
    /**
     * 
     * @return An initialized SSLContext 
     * @throws SslInitException
     * @throws InvalidConfigurationException
     */
    public static SSLContext getServerContext() throws SslInitException,
            InvalidConfigurationException {
        if (serverContext != null) {
            return serverContext;
        }
        initServerContext();
        return serverContext;
    }

    /**
     * 
     * @return An initialized SSLContext with Thermostat's only X509TrustManager
     *         registered.
     * @throws SslInitException if SSL initialization failed.
     */
    public static SSLContext getClientContext() throws SslInitException {
        if (clientContext != null) {
            return clientContext;
        }
        initClientContext();
        return clientContext;
    }

    private static void initClientContext() throws SslInitException {
        SSLContext clientCtxt = null;
        try {
            clientCtxt = SSLContext.getInstance(PROTOCOL);
            TrustManager[] tms = new TrustManager[] { TrustManagerFactory
                    .getTrustManager() };
            clientCtxt.init(null, tms, new SecureRandom());
        } catch (NoSuchAlgorithmException | KeyManagementException e) {
            e.printStackTrace();
        }
        clientContext = clientCtxt;
    }

    private static void initServerContext() throws SslInitException,
            InvalidConfigurationException {
        SSLContext serverCtxt = null;
        File trustStoreFile = SSLKeystoreConfiguration.getKeystoreFile();
        String keyStorePassword = SSLKeystoreConfiguration
                .getKeyStorePassword();
        KeyStore ks = KeyStoreProvider.getKeyStore(trustStoreFile,
                keyStorePassword);
        if (ks == null) {
            // This is bad news. We need a proper key store for retrieving the
            // server certificate.
            logReason(trustStoreFile);
            throw new SslInitException(
                    "Failed to initialize server side SSL context");
        }
        try {
            // Set up key manager factory to use our key store
            KeyManagerFactory kmf = KeyManagerFactory.getInstance(ALGORITHM);
            String keystorePassword = SSLKeystoreConfiguration.getKeyStorePassword();
            kmf.init(ks, keystorePassword.toCharArray());

            // Initialize the SSLContext to work with our key managers.
            serverCtxt = SSLContext.getInstance(PROTOCOL);
            serverCtxt.init(kmf.getKeyManagers(), null, new SecureRandom());
        } catch (GeneralSecurityException e) {
            throw new SslInitException(e);
        }
        serverContext = serverCtxt;
    }

    private static void logReason(File trustStoreFile) {
        String detail = "Reason: no keystore file specified!";
        if (trustStoreFile != null) {
            if (!trustStoreFile.exists()) {
                detail = "Reason: keystore file '" + trustStoreFile.toString() + "' does not exist!";
            } else {
                detail = "Reason: illegal keystore password!";
            }
        }
        logger.log(Level.SEVERE, "Failed to load keystore. " + detail);
    }
}