/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Atsuhiko Yamanaka, JCraft,Inc. - initial API and implementation.
 *     IBM Corporation - ongoing maintenance
 *     Aptana Inc.
 *******************************************************************************/

package org.eclipse.php.internal.server.core.tunneling;

import java.util.Enumeration;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.jsch.core.IJSchLocation;
import org.eclipse.jsch.core.IJSchService;
import org.eclipse.php.internal.server.core.Activator;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

/**
 * A SSH Tunnel session is the actual class that interacts with jcraft JSch
 * sessions. A new session is be created as needed when the
 * {@link #getSession()} method is called.
 */
public class SSHTunnelSession {
	private static final int DEFAULT_TIMEOUT = 45000;

	private static java.util.Hashtable<String, SSHTunnelSession> pool = new java.util.Hashtable<String, SSHTunnelSession>();

	private Session session;

	/**
	 * Returns a SSHTunnelSession for the given arguments. A new session will be
	 * created in case there is no active session with the given target and user
	 * name.
	 * 
	 * @param username
	 * @param password
	 * @param hostname
	 * @param port
	 * @param monitor
	 * @return A connected SSH tunnel session.
	 * @throws JSchException
	 *             In case a connection could not be established.
	 */
	public static SSHTunnelSession getSession(String username, String password, String hostname, int port,
			IProgressMonitor monitor) throws JSchException {
		String key = getPoolKey(username, hostname, port);

		try {
			SSHTunnelSession jschSession = (SSHTunnelSession) pool.get(key);
			if (jschSession != null && !jschSession.getSession().isConnected()) {
				pool.remove(key);
				jschSession = null;
			}

			if (jschSession == null) {
				IJSchService service = getJSchService();
				IJSchLocation jlocation = service.getLocation(username, hostname, port);
				Session session = null;
				try {
					session = createSession(service, jlocation, password, monitor);
				} catch (JSchException e) {
					throw e;
				}
				if (session == null) {
					throw new JSchException(Messages.SSHTunnelSession_0 + hostname);
				}
				if (session.getTimeout() != DEFAULT_TIMEOUT) {
					session.setTimeout(DEFAULT_TIMEOUT);
				}
				SSHTunnelSession schSession = new SSHTunnelSession(session);
				pool.put(key, schSession);
				return schSession;
			}
			return jschSession;
		} catch (JSchException e) {
			pool.remove(key);
			if (e.toString().indexOf("Auth cancel") != -1) { //$NON-NLS-1$
				throw new OperationCanceledException();
			}
			throw e;
		}
	}

	/*
	 * Creates a JSch session.
	 */
	private static Session createSession(IJSchService service, IJSchLocation location, String password,
			IProgressMonitor monitor) throws JSchException {
		Session session = service.createSession(location, null);
		session.setTimeout(DEFAULT_TIMEOUT);
		if (password != null) {
			session.setPassword(password);
		}
		service.connect(session, DEFAULT_TIMEOUT, monitor);
		return session;
	}

	private static IJSchService getJSchService() {
		return Activator.getDefault().getJSchService();
	}

	private static String getPoolKey(String username, String hostname, int port) {
		return username + "@" + hostname + ":" + port; //$NON-NLS-1$ //$NON-NLS-2$
	}

	/**
	 * Disconnect <b>all</b> of the SSH tunnel sessions that were statically
	 * created by this SSHTunnelSession class.
	 */
	public static void shutdown() {
		if (getJSch() != null && pool.size() > 0) {
			for (Enumeration<SSHTunnelSession> e = pool.elements(); e.hasMoreElements();) {
				SSHTunnelSession session = e.nextElement();
				try {
					session.getSession().disconnect();
				} catch (Exception ee) {
					// Ignore
				}
			}
			pool.clear();
		}
	}

	/**
	 * Returns a {@link JSch} from the JSch service.
	 * 
	 * @return {@link JSch}
	 */
	public static JSch getJSch() {
		return getJSchService().getJSch();
	}

	private SSHTunnelSession(Session session) {
		this.session = session;
	}

	/**
	 * Returns the {@link Session} instance.
	 * 
	 * @return {@link Session}
	 */
	public Session getSession() {
		return session;
	}

	/**
	 * Dispose the connection (disconnect).
	 */
	public void dispose() {
		pool.remove(getPoolKey(session.getUserName(), session.getHost(), session.getPort()));
		if (session.isConnected()) {
			session.disconnect();
		}
	}

}