/**

  * Copyright (c) 2014-2015, jcabi.com

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met: 1) Redistributions of source code must retain the above

  * copyright notice, this list of conditions and the following

  * disclaimer. 2) Redistributions in binary form must reproduce the above

  * copyright notice, this list of conditions and the following

  * disclaimer in the documentation and/or other materials provided

  * with the distribution. 3) Neither the name of the jcabi.com nor

  * the names of its contributors may be used to endorse or promote

  * products derived from this software without specific prior written

  * permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT

  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

  * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package com.jcabi.ssh;

 import com.jcabi.aspects.RetryOnFailure;

 import com.jcabi.aspects.Tv;

 import com.jcabi.log.Logger;

 import com.jcraft.jsch.JSch;

 import com.jcraft.jsch.JSchException;

 import com.jcraft.jsch.Session;

 import java.io.File;

 import java.io.IOException;

 import java.net.InetAddress;

 import java.net.URL;

 import java.net.UnknownHostException;

 import java.util.concurrent.TimeUnit;

 import lombok.EqualsAndHashCode;

 import lombok.ToString;

 import org.apache.commons.io.FileUtils;

 import org.apache.commons.io.IOUtils;

 import org.apache.commons.lang3.CharEncoding;

 /**

  * Single SSH Channel.

  *

  * <p>This class implements {@link Shell} interface. In order to use

  * it, just make an instance and call

  * {@link #exec(String,InputStream,OutputStream,OutputStream)} exec()}:

  *

  * <pre> String hello = new Shell.Plain(

  *   new SSH(

  *     "ssh.example.com", 22,

  *     "yegor", "-----BEGIN RSA PRIVATE KEY-----..."

  *   )

  * ).exec("echo 'Hello, world!'");</pre>

  *

  * <p>It is highly recommended to use classes from {@link Shell} interface,

  * they will simplify operations.</p>

  *

  * @author Yegor Bugayenko (yegor@teamed.io)

  * @version $Id: ab39f22a4b0650e2c706221da5c0bc0ccbe76188 $

  * @since 1.0

  * @see <a href="http://www.yegor256.com/2014/09/02/java-ssh-client.html">article by Yegor Bugayenko</a>

  */

 @ToString

 @EqualsAndHashCode(of = { "key" }, callSuper = true)

 @SuppressWarnings("PMD.TooManyMethods")

 public final class SSH extends AbstractSSHShell {

     /**

      * Default SSH port.

      */

     public static final int PORT = 22;

     /**

      * Private SSH key.

      */

     private final transient String key;

     /**

      * Constructor.

      * @param adr IP address

      * @param user Login

      * @param priv Private SSH key

      * @throws IOException If fails

      * @since 1.4

      */

     public SSH(final String adr, final String user, final URL priv)

         throws IOException {

         this(adr, SSH.PORT, user, priv);

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param user Login

      * @param priv Private SSH key

      * @throws IOException If fails

      * @since 1.4

      */

     public SSH(final InetAddress adr, final String user, final URL priv)

         throws IOException {

         this(adr, SSH.PORT, user, priv);

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param user Login

      * @param priv Private SSH key

      * @throws UnknownHostException If fails

      * @since 1.4

      */

     public SSH(final String adr, final String user, final String priv)

         throws UnknownHostException {

         this(adr, SSH.PORT, user, priv);

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param user Login

      * @param priv Private SSH key

      * @throws UnknownHostException If fails

      * @since 1.4

      */

     public SSH(final InetAddress adr, final String user, final String priv)

         throws UnknownHostException {

         this(adr.getCanonicalHostName(), SSH.PORT, user, priv);

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param prt Port of server

      * @param user Login

      * @param priv Private SSH key

      * @throws IOException If fails

      * @checkstyle ParameterNumberCheck (6 lines)

      * @since 1.4

      */

     public SSH(final String adr, final int prt,

         final String user, final URL priv) throws IOException {

         this(adr, prt, user, IOUtils.toString(priv));

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param prt Port of server

      * @param user Login

      * @param priv Private SSH key

      * @throws IOException If fails

      * @checkstyle ParameterNumberCheck (6 lines)

      * @since 1.4

      */

     public SSH(final InetAddress adr, final int prt,

         final String user, final URL priv) throws IOException {

         this(adr.getCanonicalHostName(), prt, user, IOUtils.toString(priv));

     }

     /**

      * Constructor.

      * @param adr IP address

      * @param prt Port of server

      * @param user Login

      * @param priv Private SSH key

      * @throws UnknownHostException If fails

      * @checkstyle ParameterNumberCheck (6 lines)

      */

     public SSH(final String adr, final int prt,

         final String user, final String priv) throws UnknownHostException {

         super(adr, prt, user);

         this.key = priv;

     }

     /**

      * Escape SSH argument.

      * @param arg Argument to escape

      * @return Escaped

      */

     public static String escape(final String arg) {

         return String.format("'%s'", arg.replace("'", "'\\''"));

     }

     // @checkstyle ProtectedMethodInFinalClassCheck (10 lines)

     @Override

     @RetryOnFailure(

         attempts = Tv.SEVEN,

         delay = 1,

         unit = TimeUnit.MINUTES,

         verbose = false,

         randomize = true,

         types = IOException.class

     )

     protected Session session() throws IOException {

         try {

             JSch.setConfig("StrictHostKeyChecking", "no");

             JSch.setLogger(new JschLogger());

             final JSch jsch = new JSch();

             final File file = File.createTempFile("jcabi-ssh", ".key");

             FileUtils.forceDeleteOnExit(file);

             FileUtils.write(

                 file,

                 this.key.replaceAll("\r", "")

                     .replaceAll("\n\\s+|\n{2,}", "\n")

                     .trim(),

                 CharEncoding.UTF_8

             );

             jsch.setHostKeyRepository(new EasyRepo());

             jsch.addIdentity(file.getAbsolutePath());

             Logger.debug(

                 this,

                 "Opening SSH session to %s@%s:%s (%d bytes in RSA key)...",

                 this.getLogin(), this.getAddr(), this.getPort(),

                 file.length()

             );

             final Session session = jsch.getSession(

                 this.getLogin(), this.getAddr(), this.getPort()

             );

             session.setServerAliveInterval(

                 (int) TimeUnit.SECONDS.toMillis(Tv.TEN)

             );

             session.setServerAliveCountMax(Tv.MILLION);

             session.connect();

             FileUtils.deleteQuietly(file);

             return session;

         } catch (final JSchException ex) {

             throw new IOException(ex);

         }

     }

 }