/*
    * Copyright (C) 2010-2012, Robin Stocker <robin@nibor.org> 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.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<>();
  		List<String> remoteBranches = new ArrayList<>();
  		List<String> tags = new ArrayList<>();
  		List<String> commits = new ArrayList<>();
  		List<String> others = new ArrayList<>();
  		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<>();
  
  		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); //$NON-NLS-1$
 		}
 		return plural + " " + StringUtils.join(names, ", ", " and "); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 	}
 }