/*
    * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com>
    * Copyright (C) 2010, Mathias Kinzler <mathias.kinzler@sap.com>
    * Copyright (C) 2016, Laurent Delaigue <laurent.delaigue@obeo.fr> 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.api;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.api.MergeCommand.FastForwardMode;
  import org.eclipse.jgit.api.MergeCommand.FastForwardMode.Merge;
  import org.eclipse.jgit.api.RebaseCommand.Operation;
  import org.eclipse.jgit.api.errors.CanceledException;
  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.dircache.DirCacheCheckout;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode;
  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.ObjectId;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.RefUpdate;
  import org.eclipse.jgit.lib.RefUpdate.Result;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.lib.RepositoryState;
  import org.eclipse.jgit.lib.SubmoduleConfig.FetchRecurseSubmodulesMode;
  import org.eclipse.jgit.merge.MergeStrategy;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.transport.FetchResult;
  import org.eclipse.jgit.transport.TagOpt;
  
  /**
   * 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 static final String DOT = "."; //$NON-NLS-1$
  
  	private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;
  
  	private BranchRebaseMode pullRebaseMode = null;
  
  	private String remote;
  
  	private String remoteBranchName;
  
  	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
  
  	private TagOpt tagOption;
  
  	private FastForwardMode fastForwardMode;
  
  	private FetchRecurseSubmodulesMode submoduleRecurseMode = null;
  
  	/**
  	 * Constructor for PullCommand.
  	 *
  	 * @param repo
  	 *            the {@link org.eclipse.jgit.lib.Repository}
  	 */
  	protected PullCommand(Repository repo) {
  		super(repo);
  	}
  
  	/**
  	 * Set progress monitor
  	 *
  	 * @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
 	 *            whether to use rebase after fetching
 	 * @return {@code this}
 	 */
 	public PullCommand setRebase(boolean useRebase) {
 		checkCallable();
 		pullRebaseMode = useRebase ? BranchRebaseMode.REBASE
 				: BranchRebaseMode.NONE;
 		return this;
 	}
 
 	/**
 	 * Sets the {@link org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode} to
 	 * use after fetching.
 	 *
 	 * <dl>
 	 * <dt>BranchRebaseMode.REBASE</dt>
 	 * <dd>Equivalent to {@code --rebase} on the command line: use rebase
 	 * instead of merge after fetching.</dd>
 	 * <dt>BranchRebaseMode.PRESERVE</dt>
 	 * <dd>Equivalent to {@code --preserve-merges} on the command line: rebase
 	 * preserving local merge commits.</dd>
 	 * <dt>BranchRebaseMode.INTERACTIVE</dt>
 	 * <dd>Equivalent to {@code --interactive} on the command line: use
 	 * interactive rebase.</dd>
 	 * <dt>BranchRebaseMode.NONE</dt>
 	 * <dd>Equivalent to {@code --no-rebase}: merge instead of rebasing.
 	 * <dt>{@code null}</dt>
 	 * <dd>Use the setting defined in the git configuration, either {@code
 	 * branch.[name].rebase} or, if not set, {@code pull.rebase}</dd>
 	 * </dl>
 	 *
 	 * 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
 	 * {@code branch.[name].rebase}, {@code branch.autosetuprebase}, and
 	 * {@code pull.rebase}.
 	 *
 	 * @param rebaseMode
 	 *            the {@link org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode}
 	 *            to use
 	 * @return {@code this}
 	 * @since 4.5
 	 */
 	public PullCommand setRebase(BranchRebaseMode rebaseMode) {
 		checkCallable();
 		pullRebaseMode = rebaseMode;
 		return this;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * Execute 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.
 	 */
 	@Override
 	public PullResult call() throws GitAPIException,
 			WrongRepositoryStateException, InvalidConfigurationException,
 			InvalidRemoteException, CanceledException,
 			RefNotFoundException, RefNotAdvertisedException, NoHeadException,
 			org.eclipse.jgit.api.errors.TransportException {
 		checkCallable();
 
 		monitor.beginTask(JGitText.get().pullTaskName, 2);
 		Config repoConfig = repo.getConfig();
 
 		String branchName = null;
 		try {
 			String fullBranch = repo.getFullBranch();
 			if (fullBranch != null
 					&& fullBranch.startsWith(Constants.R_HEADS)) {
 				branchName = fullBranch.substring(Constants.R_HEADS.length());
 			}
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					JGitText.get().exceptionCaughtDuringExecutionOfPullCommand,
 					e);
 		}
 		if (remoteBranchName == null && branchName != 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);
 		}
 		if (remoteBranchName == null) {
 			remoteBranchName = branchName;
 		}
 		if (remoteBranchName == null) {
 			throw new NoHeadException(
 					JGitText.get().cannotCheckoutFromUnbornBranch);
 		}
 
 		if (!repo.getRepositoryState().equals(RepositoryState.SAFE))
 			throw new WrongRepositoryStateException(MessageFormat.format(
 					JGitText.get().cannotPullOnARepoWithState, repo
 							.getRepositoryState().name()));
 
 		if (remote == null && branchName != 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;
 		}
 
 		// determines whether rebase should be used after fetching
 		if (pullRebaseMode == null && branchName != null) {
 			pullRebaseMode = getRebaseMode(branchName, repoConfig);
 		}
 
 
 		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).setRemote(remote)
 					.setProgressMonitor(monitor).setTagOpt(tagOption)
 					.setRecurseSubmodules(submoduleRecurseMode);
 			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));
 			}
 			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 != BranchRebaseMode.NONE) {
 			try {
 				Ref head = repo.exactRef(Constants.HEAD);
 				if (head == null) {
 					throw new NoHeadException(JGitText
 							.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
 				}
 				ObjectId headId = head.getObjectId();
 				if (headId == null) {
 					// Pull on an unborn branch: checkout
 					try (RevWalklk.html#RevWalk">RevWalk revWalk = new RevWalk(repo)) {
 						RevCommit srcCommit = revWalk
 								.parseCommit(commitToMerge);
 						DirCacheCheckout dco = new DirCacheCheckout(repo,
 								repo.lockDirCache(), srcCommit.getTree());
 						dco.setFailOnConflict(true);
 						dco.setProgressMonitor(monitor);
 						dco.checkout();
 						RefUpdate refUpdate = repo
 								.updateRef(head.getTarget().getName());
 						refUpdate.setNewObjectId(commitToMerge);
 						refUpdate.setExpectedOldObjectId(null);
 						refUpdate.setRefLogMessage("initial pull", false); //$NON-NLS-1$
 						if (refUpdate.update() != Result.NEW) {
 							throw new NoHeadException(JGitText
 									.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
 						}
 						monitor.endTask();
 						return new PullResult(fetchRes, remote,
 								RebaseResult.result(
 										RebaseResult.Status.FAST_FORWARD,
 										srcCommit));
 					}
 				}
 			} catch (NoHeadException e) {
 				throw e;
 			} catch (IOException e) {
 				throw new JGitInternalException(JGitText
 						.get().exceptionCaughtDuringExecutionOfPullCommand, e);
 			}
 			RebaseCommand rebase = new RebaseCommand(repo);
 			RebaseResult rebaseRes = rebase.setUpstream(commitToMerge)
 					.setUpstreamName(upstreamName).setProgressMonitor(monitor)
 					.setOperation(Operation.BEGIN).setStrategy(strategy)
 					.setPreserveMerges(
 							pullRebaseMode == BranchRebaseMode.PRESERVE)
 					.call();
 			result = new PullResult(fetchRes, remote, rebaseRes);
 		} else {
 			MergeCommand merge = new MergeCommand(repo);
 			MergeResult mergeRes = merge.include(upstreamName, commitToMerge)
 					.setStrategy(strategy).setProgressMonitor(monitor)
 					.setFastForward(getFastForwardMode()).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
 	 *            name of the remote to pull from
 	 * @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
 	 *            remote branch name to be used for pull operation
 	 * @return {@code this}
 	 * @since 3.3
 	 */
 	public PullCommand setRemoteBranchName(String remoteBranchName) {
 		checkCallable();
 		this.remoteBranchName = remoteBranchName;
 		return this;
 	}
 
 	/**
 	 * Get the remote name used for pull operation
 	 *
 	 * @return the remote used for the pull operation if it was set explicitly
 	 * @since 3.3
 	 */
 	public String getRemote() {
 		return remote;
 	}
 
 	/**
 	 * Get the remote branch name for the pull operation
 	 *
 	 * @return the remote branch name used for the pull operation if it was set
 	 *         explicitly
 	 * @since 3.3
 	 */
 	public String getRemoteBranchName() {
 		return remoteBranchName;
 	}
 
 	/**
 	 * Set the @{code MergeStrategy}
 	 *
 	 * @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;
 	}
 
 	/**
 	 * Set the specification of annotated tag behavior during fetch
 	 *
 	 * @param tagOpt
 	 *            the {@link org.eclipse.jgit.transport.TagOpt}
 	 * @return {@code this}
 	 * @since 4.7
 	 */
 	public PullCommand setTagOpt(TagOpt tagOpt) {
 		checkCallable();
 		this.tagOption = tagOpt;
 		return this;
 	}
 
 	/**
 	 * Set the fast forward mode. It is used if pull is configured to do a merge
 	 * as opposed to rebase. If non-{@code null} takes precedence over the
 	 * fast-forward mode configured in git config.
 	 *
 	 * @param fastForwardMode
 	 *            corresponds to the --ff/--no-ff/--ff-only options. If
 	 *            {@code null} use the value of {@code pull.ff} configured in
 	 *            git config. If {@code pull.ff} is not configured fall back to
 	 *            the value of {@code merge.ff}. If {@code merge.ff} is not
 	 *            configured --ff is the built-in default.
 	 * @return {@code this}
 	 * @since 4.9
 	 */
 	public PullCommand setFastForward(
 			@Nullable FastForwardMode fastForwardMode) {
 		checkCallable();
 		this.fastForwardMode = fastForwardMode;
 		return this;
 	}
 
 	/**
 	 * Set the mode to be used for recursing into submodules.
 	 *
 	 * @param recurse
 	 *            the
 	 *            {@link org.eclipse.jgit.lib.SubmoduleConfig.FetchRecurseSubmodulesMode}
 	 *            to be used for recursing into submodules
 	 * @return {@code this}
 	 * @since 4.7
 	 * @see FetchCommand#setRecurseSubmodules(FetchRecurseSubmodulesMode)
 	 */
 	public PullCommand setRecurseSubmodules(
 			@Nullable FetchRecurseSubmodulesMode recurse) {
 		this.submoduleRecurseMode = recurse;
 		return this;
 	}
 
 	/**
 	 * Reads the rebase mode to use for a pull command from the repository
 	 * configuration. This is the value defined for the configurations
 	 * {@code branch.[branchName].rebase}, or,if not set, {@code pull.rebase}.
 	 * If neither is set, yields
 	 * {@link org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode#NONE}.
 	 *
 	 * @param branchName
 	 *            name of the local branch
 	 * @param config
 	 *            the {@link org.eclipse.jgit.lib.Config} to read the value from
 	 * @return the {@link org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode}
 	 * @since 4.5
 	 */
 	public static BranchRebaseMode getRebaseMode(String branchName,
 			Config config) {
 		BranchRebaseMode mode = config.getEnum(BranchRebaseMode.values(),
 				ConfigConstants.CONFIG_BRANCH_SECTION,
 				branchName, ConfigConstants.CONFIG_KEY_REBASE, null);
 		if (mode == null) {
 			mode = config.getEnum(BranchRebaseMode.values(),
 					ConfigConstants.CONFIG_PULL_SECTION, null,
 					ConfigConstants.CONFIG_KEY_REBASE, BranchRebaseMode.NONE);
 		}
 		return mode;
 	}
 
 	private FastForwardMode getFastForwardMode() {
 		if (fastForwardMode != null) {
 			return fastForwardMode;
 		}
 		Config config = repo.getConfig();
 		Merge ffMode = config.getEnum(Merge.values(),
 				ConfigConstants.CONFIG_PULL_SECTION, null,
 				ConfigConstants.CONFIG_KEY_FF, null);
 		return ffMode != null ? FastForwardMode.valueOf(ffMode) : null;
 	}
 }