/*
 * Copyright (C) 2011, 2014 Christian Halstrick <christian.halstrick@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;
 * 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 org.eclipse.jgit.pgm;

import java.io.IOException;
import java.text.MessageFormat;
import java.util.Map;

import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.api.MergeCommand;
import org.eclipse.jgit.api.MergeCommand.FastForwardMode;
import org.eclipse.jgit.api.MergeResult;
import org.eclipse.jgit.api.errors.CheckoutConflictException;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.merge.MergeStrategy;
import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
import org.eclipse.jgit.pgm.internal.CLIText;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.kohsuke.args4j.Argument;
import org.kohsuke.args4j.Option;

@Command(common = true, usage = "usage_MergesTwoDevelopmentHistories")
class Merge extends TextBuiltin {

	@Option(name = "--strategy", aliases = { "-s" }, usage = "usage_mergeStrategy")
	private String strategyName;

	@Option(name = "--squash", usage = "usage_squash")
	private boolean squash;

	@Option(name = "--no-commit", usage = "usage_noCommit")
	private boolean noCommit = false;

	private MergeStrategy mergeStrategy = MergeStrategy.RECURSIVE;

	@Argument(required = true, metaVar = "metaVar_ref", usage = "usage_mergeRef")
	private String ref;

	private FastForwardMode ff = FastForwardMode.FF;

	@Option(name = "--ff", usage = "usage_mergeFf")
	void ff(@SuppressWarnings("unused") final boolean ignored) {
		ff = FastForwardMode.FF;
	}

	@Option(name = "--no-ff", usage = "usage_mergeNoFf")
	void noff(@SuppressWarnings("unused") final boolean ignored) {
		ff = FastForwardMode.NO_FF;
	}

	@Option(name = "--ff-only", usage = "usage_mergeFfOnly")
	void ffonly(@SuppressWarnings("unused") final boolean ignored) {
		ff = FastForwardMode.FF_ONLY;
	}

	@Option(name = "-m", usage = "usage_message")
	private String message;

	/** {@inheritDoc} */
	@Override
	protected void run() throws Exception {
		if (squash && ff == FastForwardMode.NO_FF)
			throw die(CLIText.get().cannotCombineSquashWithNoff);
		// determine the merge strategy
		if (strategyName != null) {
			mergeStrategy = MergeStrategy.get(strategyName);
			if (mergeStrategy == null)
				throw die(MessageFormat.format(
						CLIText.get().unknownMergeStrategy, strategyName));
		}

		// determine the other revision we want to merge with HEAD
		final Ref srcRef = db.findRef(ref);
		final ObjectId src = db.resolve(ref + "^{commit}"); //$NON-NLS-1$
		if (src == null)
			throw die(MessageFormat.format(
					CLIText.get().refDoesNotExistOrNoCommit, ref));

		Ref oldHead = getOldHead();
		MergeResult result;
		try (Git git = new Git(db)) {
			MergeCommand mergeCmd = git.merge().setStrategy(mergeStrategy)
					.setSquash(squash).setFastForward(ff).setCommit(!noCommit);
			if (srcRef != null)
				mergeCmd.include(srcRef);
			else
				mergeCmd.include(src);

			if (message != null)
				mergeCmd.setMessage(message);

			try {
				result = mergeCmd.call();
			} catch (CheckoutConflictException e) {
				result = new MergeResult(e.getConflictingPaths()); // CHECKOUT_CONFLICT
			}
		}

		switch (result.getMergeStatus()) {
		case ALREADY_UP_TO_DATE:
			if (squash)
				outw.print(CLIText.get().nothingToSquash);
			outw.println(CLIText.get().alreadyUpToDate);
			break;
		case FAST_FORWARD:
			ObjectId oldHeadId = oldHead.getObjectId();
			if (oldHeadId != null) {
				String oldId = oldHeadId.abbreviate(7).name();
				String newId = result.getNewHead().abbreviate(7).name();
				outw.println(MessageFormat.format(CLIText.get().updating, oldId,
						newId));
			}
			outw.println(result.getMergeStatus().toString());
			break;
		case CHECKOUT_CONFLICT:
			outw.println(CLIText.get().mergeCheckoutConflict);
			for (String collidingPath : result.getCheckoutConflicts())
				outw.println("\t" + collidingPath); //$NON-NLS-1$
			outw.println(CLIText.get().mergeCheckoutFailed);
			break;
		case CONFLICTING:
			for (String collidingPath : result.getConflicts().keySet())
				outw.println(MessageFormat.format(CLIText.get().mergeConflict,
						collidingPath));
			outw.println(CLIText.get().mergeFailed);
			break;
		case FAILED:
			for (Map.Entry<String, MergeFailureReason> entry : result
					.getFailingPaths().entrySet())
				switch (entry.getValue()) {
				case DIRTY_WORKTREE:
				case DIRTY_INDEX:
					outw.println(CLIText.get().dontOverwriteLocalChanges);
					outw.println("        " + entry.getKey()); //$NON-NLS-1$
					break;
				case COULD_NOT_DELETE:
					outw.println(CLIText.get().cannotDeleteFile);
					outw.println("        " + entry.getKey()); //$NON-NLS-1$
					break;
				}
			break;
		case MERGED:
			String name;
			if (!isMergedInto(oldHead, src))
				name = mergeStrategy.getName();
			else
				name = "recursive"; //$NON-NLS-1$
			outw.println(MessageFormat.format(CLIText.get().mergeMadeBy, name));
			break;
		case MERGED_NOT_COMMITTED:
			outw.println(CLIText.get().mergeWentWellStoppedBeforeCommitting);
			break;
		case MERGED_SQUASHED:
		case FAST_FORWARD_SQUASHED:
		case MERGED_SQUASHED_NOT_COMMITTED:
			outw.println(CLIText.get().mergedSquashed);
			outw.println(CLIText.get().mergeWentWellStoppedBeforeCommitting);
			break;
		case ABORTED:
			throw die(CLIText.get().ffNotPossibleAborting);
		case NOT_SUPPORTED:
			outw.println(MessageFormat.format(
					CLIText.get().unsupportedOperation, result.toString()));
		}
	}

	private Ref getOldHead() throws IOException {
		Ref oldHead = db.exactRef(Constants.HEAD);
		if (oldHead == null) {
			throw die(CLIText.get().onBranchToBeBorn);
		}
		return oldHead;
	}

	private boolean isMergedInto(Ref oldHead, AnyObjectId src)
			throws IOException {
		try (RevWalk revWalk = new RevWalk(db)) {
			ObjectId oldHeadObjectId = oldHead.getPeeledObjectId();
			if (oldHeadObjectId == null)
				oldHeadObjectId = oldHead.getObjectId();
			RevCommit oldHeadCommit = revWalk.lookupCommit(oldHeadObjectId);
			RevCommit srcCommit = revWalk.lookupCommit(src);
			return revWalk.isMergedInto(oldHeadCommit, srcCommit);
		}
	}
}