/*
    * Copyright (C) 2018, Markus Duft <markus.duft@ssi-schaefer.com> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  package org.eclipse.jgit.util;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.errors.CommandFailedException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.transport.CredentialsProvider;
  import org.eclipse.jgit.transport.RemoteSession;
  import org.eclipse.jgit.transport.SshSessionFactory;
  import org.eclipse.jgit.transport.URIish;
  import org.eclipse.jgit.util.io.MessageWriter;
  import org.eclipse.jgit.util.io.StreamCopyThread;
  
  /**
   * Extra utilities to support usage of SSH.
   *
   * @since 5.0
   */
  public class SshSupport {
  
  	/**
  	 * Utility to execute a remote SSH command and read the first line of
  	 * output.
  	 *
  	 * @param sshUri
  	 *            the SSH remote URI
  	 * @param provider
  	 *            the {@link CredentialsProvider} or <code>null</code>.
  	 * @param fs
  	 *            the {@link FS} implementation passed to
  	 *            {@link SshSessionFactory}
  	 * @param command
  	 *            the remote command to execute.
  	 * @param timeout
  	 *            a timeout in seconds. The timeout may be exceeded in corner
  	 *            cases.
  	 * @return The entire output read from stdout.
  	 * @throws IOException
  	 * @throws CommandFailedException
  	 *             if the ssh command execution failed, error message contains
  	 *             the content of stderr.
  	 */
  	public static String runSshCommand(URIish sshUri,
  			@Nullable CredentialsProvider provider, FS fs, String command,
  			int timeout) throws IOException, CommandFailedException {
  		RemoteSession session = null;
  		Process process = null;
  		StreamCopyThread errorThread = null;
  		StreamCopyThread outThread = null;
  		CommandFailedException failure = null;
  		@SuppressWarnings("resource")
  		MessageWriter stderr = new MessageWriter();
  		String out;
  		try (MessageWriterter.html#MessageWriter">MessageWriter stdout = new MessageWriter()) {
  			session = SshSessionFactory.getInstance().getSession(sshUri,
  					provider, fs, 1000 * timeout);
  			process = session.exec(command, 0);
  			errorThread = new StreamCopyThread(process.getErrorStream(),
  					stderr.getRawStream());
  			errorThread.start();
  			outThread = new StreamCopyThread(process.getInputStream(),
  					stdout.getRawStream());
  			outThread.start();
  			try {
  				// waitFor with timeout has a bug - JSch' exitValue() throws the
  				// wrong exception type :(
  				if (process.waitFor() == 0) {
  					out = stdout.toString();
  				} else {
  					out = null; // still running after timeout
  				}
  			} catch (InterruptedException e) {
  				out = null; // error
  			}
  		} finally {
  			if (errorThread != null) {
  				try {
  					errorThread.halt();
  				} catch (InterruptedException e) {
  					// Stop waiting and return anyway.
  				} finally {
  					errorThread = null;
  				}
  			}
  			if (outThread != null) {
  				try {
  					outThread.halt();
  				} catch (InterruptedException e) {
 					// Stop waiting and return anyway.
 				} finally {
 					outThread = null;
 				}
 			}
 			if (process != null) {
 				if (process.exitValue() != 0) {
 					failure = new CommandFailedException(process.exitValue(),
 							MessageFormat.format(
 							JGitText.get().sshCommandFailed, command,
 							stderr.toString()));
 				}
 				process.destroy();
 			}
 			stderr.close();
 			if (session != null) {
 				SshSessionFactory.getInstance().releaseSession(session);
 			}
 		}
 		if (failure != null) {
 			throw failure;
 		}
 		return out;
 	}
 
 }