/*
    * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com>
    * Copyright (C) 2010, Mathias Kinzler <mathias.kinzler@sap.com>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - 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.
   *
   * - Neither the name of the Eclipse Foundation, Inc. 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 OWNER 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;
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  package org.eclipse.jgit.api;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  
  import org.eclipse.jgit.api.RebaseCommand.Operation;
  import org.eclipse.jgit.api.errors.CanceledException;
  import org.eclipse.jgit.api.errors.DetachedHeadException;
  import org.eclipse.jgit.api.errors.GitAPIException;
  import org.eclipse.jgit.api.errors.InvalidConfigurationException;
  import org.eclipse.jgit.api.errors.InvalidRemoteException;
  import org.eclipse.jgit.api.errors.JGitInternalException;
  import org.eclipse.jgit.api.errors.NoHeadException;
  import org.eclipse.jgit.api.errors.RefNotAdvertisedException;
  import org.eclipse.jgit.api.errors.RefNotFoundException;
  import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Config;
  import org.eclipse.jgit.lib.ConfigConstants;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.lib.RepositoryState;
  import org.eclipse.jgit.merge.MergeStrategy;
  import org.eclipse.jgit.transport.FetchResult;
  
  /**
   * The Pull command
   *
   * @see <a href="http://www.kernel.org/pub/software/scm/git/docs/git-pull.html"
   *      >Git documentation about Pull</a>
   */
  public class PullCommand extends TransportCommand<PullCommand, PullResult> {
  
  	private final static String DOT = "."; //$NON-NLS-1$
  
  	private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;
  
  	private PullRebaseMode pullRebaseMode = null;
  
  	private String remote;
  
  	private String remoteBranchName;
  
  	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
  
  	private enum PullRebaseMode implements Config.ConfigEnum {
  		REBASE_PRESERVE("preserve", true, true), //$NON-NLS-1$
  		REBASE("true", true, false), //$NON-NLS-1$
  		NO_REBASE("false", false, false); //$NON-NLS-1$
  
  		private final String configValue;
  
 		private final boolean rebase;
 
 		private final boolean preserveMerges;
 
 		PullRebaseMode(String configValue, boolean rebase,
 				boolean preserveMerges) {
 			this.configValue = configValue;
 			this.rebase = rebase;
 			this.preserveMerges = preserveMerges;
 		}
 
 		public String toConfigValue() {
 			return configValue;
 		}
 
 		public boolean matchConfigValue(String in) {
 			return in.equals(configValue);
 		}
 	}
 
 	/**
 	 * @param repo
 	 */
 	protected PullCommand(Repository repo) {
 		super(repo);
 	}
 
 	/**
 	 * @param monitor
 	 *            a progress monitor
 	 * @return this instance
 	 */
 	public PullCommand setProgressMonitor(ProgressMonitor monitor) {
 		if (monitor == null) {
 			monitor = NullProgressMonitor.INSTANCE;
 		}
 		this.monitor = monitor;
 		return this;
 	}
 
 	/**
 	 * Set if rebase should be used after fetching. If set to true, rebase is
 	 * used instead of merge. This is equivalent to --rebase on the command
 	 * line.
 	 * <p>
 	 * If set to false, merge is used after fetching, overriding the
 	 * configuration file. This is equivalent to --no-rebase on the command
 	 * line.
 	 * <p>
 	 * This setting overrides the settings in the configuration file. By
 	 * default, the setting in the repository configuration file is used.
 	 * <p>
 	 * A branch can be configured to use rebase by default. See
 	 * branch.[name].rebase and branch.autosetuprebase.
 	 *
 	 * @param useRebase
 	 * @return {@code this}
 	 */
 	public PullCommand setRebase(boolean useRebase) {
 		checkCallable();
 		pullRebaseMode = useRebase ? PullRebaseMode.REBASE : PullRebaseMode.NO_REBASE;
 		return this;
 	}
 
 	/**
 	 * Executes the {@code Pull} command with all the options and parameters
 	 * collected by the setter methods (e.g.
 	 * {@link #setProgressMonitor(ProgressMonitor)}) of this class. Each
 	 * instance of this class should only be used for one invocation of the
 	 * command. Don't call this method twice on an instance.
 	 *
 	 * @return the result of the pull
 	 * @throws WrongRepositoryStateException
 	 * @throws InvalidConfigurationException
 	 * @throws DetachedHeadException
 	 * @throws InvalidRemoteException
 	 * @throws CanceledException
 	 * @throws RefNotFoundException
 	 * @throws RefNotAdvertisedException
 	 * @throws NoHeadException
 	 * @throws org.eclipse.jgit.api.errors.TransportException
 	 * @throws GitAPIException
 	 */
 	public PullResult call() throws GitAPIException,
 			WrongRepositoryStateException, InvalidConfigurationException,
 			DetachedHeadException, InvalidRemoteException, CanceledException,
 			RefNotFoundException, RefNotAdvertisedException, NoHeadException,
 			org.eclipse.jgit.api.errors.TransportException {
 		checkCallable();
 
 		monitor.beginTask(JGitText.get().pullTaskName, 2);
 
 		String branchName;
 		try {
 			String fullBranch = repo.getFullBranch();
 			if (fullBranch == null)
 				throw new NoHeadException(
 						JGitText.get().pullOnRepoWithoutHEADCurrentlyNotSupported);
 			if (!fullBranch.startsWith(Constants.R_HEADS)) {
 				// we can not pull if HEAD is detached and branch is not
 				// specified explicitly
 				throw new DetachedHeadException();
 			}
 			branchName = fullBranch.substring(Constants.R_HEADS.length());
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					JGitText.get().exceptionCaughtDuringExecutionOfPullCommand,
 					e);
 		}
 
 		if (!repo.getRepositoryState().equals(RepositoryState.SAFE))
 			throw new WrongRepositoryStateException(MessageFormat.format(
 					JGitText.get().cannotPullOnARepoWithState, repo
 							.getRepositoryState().name()));
 
 		Config repoConfig = repo.getConfig();
 		if (remote == null) {
 			// get the configured remote for the currently checked out branch
 			// stored in configuration key branch.<branch name>.remote
 			remote = repoConfig.getString(
 					ConfigConstants.CONFIG_BRANCH_SECTION, branchName,
 					ConfigConstants.CONFIG_KEY_REMOTE);
 		}
 		if (remote == null)
 			// fall back to default remote
 			remote = Constants.DEFAULT_REMOTE_NAME;
 
 		if (remoteBranchName == null)
 			// get the name of the branch in the remote repository
 			// stored in configuration key branch.<branch name>.merge
 			remoteBranchName = repoConfig.getString(
 					ConfigConstants.CONFIG_BRANCH_SECTION, branchName,
 					ConfigConstants.CONFIG_KEY_MERGE);
 
 		// determines whether rebase should be used after fetching
 		if (pullRebaseMode == null) {
 			pullRebaseMode = getRebaseMode(branchName, repoConfig);
 		}
 
 		if (remoteBranchName == null)
 			remoteBranchName = branchName;
 
 		final boolean isRemote = !remote.equals("."); //$NON-NLS-1$
 		String remoteUri;
 		FetchResult fetchRes;
 		if (isRemote) {
 			remoteUri = repoConfig.getString(
 					ConfigConstants.CONFIG_REMOTE_SECTION, remote,
 					ConfigConstants.CONFIG_KEY_URL);
 			if (remoteUri == null) {
 				String missingKey = ConfigConstants.CONFIG_REMOTE_SECTION + DOT
 						+ remote + DOT + ConfigConstants.CONFIG_KEY_URL;
 				throw new InvalidConfigurationException(MessageFormat.format(
 						JGitText.get().missingConfigurationForKey, missingKey));
 			}
 
 			if (monitor.isCancelled())
 				throw new CanceledException(MessageFormat.format(
 						JGitText.get().operationCanceled,
 						JGitText.get().pullTaskName));
 
 			FetchCommand fetch = new FetchCommand(repo);
 			fetch.setRemote(remote);
 			fetch.setProgressMonitor(monitor);
 			configure(fetch);
 
 			fetchRes = fetch.call();
 		} else {
 			// we can skip the fetch altogether
 			remoteUri = JGitText.get().localRepository;
 			fetchRes = null;
 		}
 
 		monitor.update(1);
 
 		if (monitor.isCancelled())
 			throw new CanceledException(MessageFormat.format(
 					JGitText.get().operationCanceled,
 					JGitText.get().pullTaskName));
 
 		// we check the updates to see which of the updated branches
 		// corresponds
 		// to the remote branch name
 		AnyObjectId commitToMerge;
 		if (isRemote) {
 			Ref r = null;
 			if (fetchRes != null) {
 				r = fetchRes.getAdvertisedRef(remoteBranchName);
 				if (r == null)
 					r = fetchRes.getAdvertisedRef(Constants.R_HEADS
 							+ remoteBranchName);
 			}
 			if (r == null) {
 				throw new RefNotAdvertisedException(MessageFormat.format(
 						JGitText.get().couldNotGetAdvertisedRef, remote,
 						remoteBranchName));
 			} else {
 				commitToMerge = r.getObjectId();
 			}
 		} else {
 			try {
 				commitToMerge = repo.resolve(remoteBranchName);
 				if (commitToMerge == null)
 					throw new RefNotFoundException(MessageFormat.format(
 							JGitText.get().refNotResolved, remoteBranchName));
 			} catch (IOException e) {
 				throw new JGitInternalException(
 						JGitText.get().exceptionCaughtDuringExecutionOfPullCommand,
 						e);
 			}
 		}
 
 		String upstreamName = MessageFormat.format(
 				JGitText.get().upstreamBranchName,
 				Repository.shortenRefName(remoteBranchName), remoteUri);
 
 		PullResult result;
 		if (pullRebaseMode.rebase) {
 			RebaseCommand rebase = new RebaseCommand(repo);
 			RebaseResult rebaseRes = rebase.setUpstream(commitToMerge)
 					.setUpstreamName(upstreamName).setProgressMonitor(monitor)
 					.setOperation(Operation.BEGIN).setStrategy(strategy)
 					.setPreserveMerges(pullRebaseMode.preserveMerges)
 					.call();
 			result = new PullResult(fetchRes, remote, rebaseRes);
 		} else {
 			MergeCommand merge = new MergeCommand(repo);
 			merge.include(upstreamName, commitToMerge);
 			merge.setStrategy(strategy);
 			MergeResult mergeRes = merge.call();
 			monitor.update(1);
 			result = new PullResult(fetchRes, remote, mergeRes);
 		}
 		monitor.endTask();
 		return result;
 	}
 
 	/**
 	 * The remote (uri or name) to be used for the pull operation. If no remote
 	 * is set, the branch's configuration will be used. If the branch
 	 * configuration is missing the default value of
 	 * <code>Constants.DEFAULT_REMOTE_NAME</code> will be used.
 	 *
 	 * @see Constants#DEFAULT_REMOTE_NAME
 	 * @param remote
 	 * @return {@code this}
 	 * @since 3.3
 	 */
 	public PullCommand setRemote(String remote) {
 		checkCallable();
 		this.remote = remote;
 		return this;
 	}
 
 	/**
 	 * The remote branch name to be used for the pull operation. If no
 	 * remoteBranchName is set, the branch's configuration will be used. If the
 	 * branch configuration is missing the remote branch with the same name as
 	 * the current branch is used.
 	 *
 	 * @param remoteBranchName
 	 * @return {@code this}
 	 * @since 3.3
 	 */
 	public PullCommand setRemoteBranchName(String remoteBranchName) {
 		checkCallable();
 		this.remoteBranchName = remoteBranchName;
 		return this;
 	}
 
 	/**
 	 * @return the remote used for the pull operation if it was set explicitly
 	 * @since 3.3
 	 */
 	public String getRemote() {
 		return remote;
 	}
 
 	/**
 	 * @return the remote branch name used for the pull operation if it was set
 	 *         explicitly
 	 * @since 3.3
 	 */
 	public String getRemoteBranchName() {
 		return remoteBranchName;
 	}
 
 	/**
 	 * @param strategy
 	 *            The merge strategy to use during this pull operation.
 	 * @return {@code this}
 	 * @since 3.4
 	 */
 	public PullCommand setStrategy(MergeStrategy strategy) {
 		this.strategy = strategy;
 		return this;
 	}
 
 	private static PullRebaseMode getRebaseMode(String branchName, Config config) {
 		PullRebaseMode mode = config.getEnum(PullRebaseMode.values(),
 				ConfigConstants.CONFIG_PULL_SECTION, null,
 				ConfigConstants.CONFIG_KEY_REBASE, PullRebaseMode.NO_REBASE);
 		mode = config.getEnum(PullRebaseMode.values(),
 				ConfigConstants.CONFIG_BRANCH_SECTION,
 				branchName, ConfigConstants.CONFIG_KEY_REBASE, mode);
 		return mode;
 	}
 }