/*
 * Copyright (C) 2010-2012, Robin Stocker <robin@nibor.org>
 * 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.merge;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.util.ChangeIdUtil;
import org.eclipse.jgit.util.StringUtils;

/**
 * Formatter for constructing the commit message for a merge commit.
 * <p>
 * The format should be the same as C Git does it, for compatibility.
 */
public class MergeMessageFormatter {
	/**
	 * Construct the merge commit message.
	 *
	 * @param refsToMerge
	 *            the refs which will be merged
	 * @param target
	 *            the branch ref which will be merged into
	 * @return merge commit message
	 */
	public String format(List<Ref> refsToMerge, Ref target) {
		StringBuilder sb = new StringBuilder();
		sb.append("Merge "); //$NON-NLS-1$

		List<String> branches = new ArrayList<String>();
		List<String> remoteBranches = new ArrayList<String>();
		List<String> tags = new ArrayList<String>();
		List<String> commits = new ArrayList<String>();
		List<String> others = new ArrayList<String>();
		for (Ref ref : refsToMerge) {
			if (ref.getName().startsWith(Constants.R_HEADS)) {
				branches.add("'" + Repository.shortenRefName(ref.getName()) //$NON-NLS-1$
						+ "'"); //$NON-NLS-1$
			} else if (ref.getName().startsWith(Constants.R_REMOTES)) {
				remoteBranches.add("'" //$NON-NLS-1$
						+ Repository.shortenRefName(ref.getName()) + "'"); //$NON-NLS-1$
			} else if (ref.getName().startsWith(Constants.R_TAGS)) {
				tags.add("'" + Repository.shortenRefName(ref.getName()) + "'"); //$NON-NLS-1$ //$NON-NLS-2$
			} else {
				ObjectId objectId = ref.getObjectId();
				if (objectId != null && ref.getName().equals(objectId.getName())) {
					commits.add("'" + ref.getName() + "'"); //$NON-NLS-1$ //$NON-NLS-2$
				} else {
					others.add(ref.getName());
				}
			}
		}

		List<String> listings = new ArrayList<String>();

		if (!branches.isEmpty())
			listings.add(joinNames(branches, "branch", "branches")); //$NON-NLS-1$//$NON-NLS-2$

		if (!remoteBranches.isEmpty())
			listings.add(joinNames(remoteBranches, "remote-tracking branch", //$NON-NLS-1$
					"remote-tracking branches")); //$NON-NLS-1$

		if (!tags.isEmpty())
			listings.add(joinNames(tags, "tag", "tags")); //$NON-NLS-1$ //$NON-NLS-2$

		if (!commits.isEmpty())
			listings.add(joinNames(commits, "commit", "commits")); //$NON-NLS-1$ //$NON-NLS-2$

		if (!others.isEmpty())
			listings.add(StringUtils.join(others, ", ", " and ")); //$NON-NLS-1$ //$NON-NLS-2$

		sb.append(StringUtils.join(listings, ", ")); //$NON-NLS-1$

		String targetName = target.getLeaf().getName();
		if (!targetName.equals(Constants.R_HEADS + Constants.MASTER)) {
			String targetShortName = Repository.shortenRefName(targetName);
			sb.append(" into " + targetShortName); //$NON-NLS-1$
		}

		return sb.toString();
	}

	/**
	 * Add section with conflicting paths to merge message.
	 *
	 * @param message
	 *            the original merge message
	 * @param conflictingPaths
	 *            the paths with conflicts
	 * @return merge message with conflicting paths added
	 */
	public String formatWithConflicts(String message,
			List<String> conflictingPaths) {
		StringBuilder sb = new StringBuilder();
		String[] lines = message.split("\n"); //$NON-NLS-1$
		int firstFooterLine = ChangeIdUtil.indexOfFirstFooterLine(lines);
		for (int i = 0; i < firstFooterLine; i++)
			sb.append(lines[i]).append('\n');
		if (firstFooterLine == lines.length && message.length() != 0)
			sb.append('\n');
		addConflictsMessage(conflictingPaths, sb);
		if (firstFooterLine < lines.length)
			sb.append('\n');
		for (int i = firstFooterLine; i < lines.length; i++)
			sb.append(lines[i]).append('\n');
		return sb.toString();
	}

	private static void addConflictsMessage(List<String> conflictingPaths,
			StringBuilder sb) {
		sb.append("Conflicts:\n"); //$NON-NLS-1$
		for (String conflictingPath : conflictingPaths)
			sb.append('\t').append(conflictingPath).append('\n');
	}

	private static String joinNames(List<String> names, String singular,
			String plural) {
		if (names.size() == 1)
			return singular + " " + names.get(0); //$NON-NLS-1$
		else
			return plural + " " + StringUtils.join(names, ", ", " and "); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	}
}