/*******************************************************************************
    * Copyright (c) 2007, 2014 Massimiliano Ziccardi
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *******************************************************************************/
  package it.jnrpe.plugin.utils;
  
  import it.jnrpe.ICommandLine;
  import it.jnrpe.Status;
  import it.jnrpe.plugins.MetricGatheringException;
  
  import com.jcraft.jsch.JSch;
  import com.jcraft.jsch.Session;
  
  /**
   * SSH utility class
   * 
   * @author Frederico Campos
   * 
   */
  public class SshUtils {
  
  	/**
  	 * Default timeout.
  	 */
  	protected static final int DEFAULT_TIMEOUT = 10;
  
  	/**
  	 * Default HTTP port.
  	 */
  	protected static final int DEFAULT_PORT = 22;
  
  	/**
  	 * Starts an ssh session
  	 * 
  	 * @param cl
  	 * @return
  	 * @throws MetricGatheringException
  	 * @throws Exception
  	 *             Session
  	 */
  	public static Session getSession(final ICommandLine cl)
  			throws MetricGatheringException, Exception {
  		JSch jsch = new JSch();
  		Session session = null;
  		int timeout = DEFAULT_TIMEOUT;
  		int port = cl.hasOption("port") ? Integer.parseInt(cl.getOptionValue("port")) : + DEFAULT_PORT;
  		String hostname = cl.getOptionValue("hostname");
  		String username = cl.getOptionValue("username");
  		String password = cl.getOptionValue("password");
  		String key = cl.getOptionValue("key");
  		if (cl.getOptionValue("timeout") != null) {
  			try {
  				timeout = Integer.parseInt(cl.getOptionValue("timeout"));
  			} catch (NumberFormatException e) {
  				throw new MetricGatheringException(
  						"Invalid numeric value for timeout.", Status.CRITICAL,
  						e);
  			}
  		}
  		session = jsch.getSession(username, hostname, port);
  		if (key == null) {
  			session.setConfig("StrictHostKeyChecking", "no");
  			session.setPassword(password);
  		} else {
  			jsch.addIdentity(key);
  		}
  		session.connect(timeout * 1000);
  		return session;
  	}
  
  }