Enhance MergeResult to report conflicts, etc

The MergeResult class is enhanced to report more data about a
three-way merge. Information about conflicts and the base, ours,
theirs commits can be retrived.

Change-Id: Iaaf41a1f4002b8fe3ddfa62dc73c787f363460c2
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

3 files changed, 136 insertions, 25 deletions

diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
index a9878f8d29..faeb1d53f9 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
@@ -222,7 +222,7 @@ lockOnNotHeld=Lock on {0} not held.
 malformedpersonIdentString=Malformed PersonIdent string (no < was found): {0}
 mergeStrategyAlreadyExistsAsDefault=Merge strategy "{0}" already exists as a default strategy
 mergeStrategyDoesNotSupportHeads=merge strategy {0} does not support {1} heads to be merged into HEAD
-mergeUsingStrategyResultedInDescription=Merge using strategy {0} resulted in: {1}. {2}
+mergeUsingStrategyResultedInDescription=Merge of revisions {0} with base {1} using strategy {2} resulted in: {3}. {4}
 missingAccesskey=Missing accesskey.
 missingDeltaBase=delta base
 missingForwardImageInGITBinaryPatch=Missing forward-image in GIT binary patch
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
index 972aa618ad..4d37c28e0a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
@@ -114,7 +114,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 		try {
 			Ref head = repo.getRef(Constants.HEAD);
 			if (head == null)
-				throw new NoHeadException(JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
+				throw new NoHeadException(
+						JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
 			StringBuilder refLogMessage = new StringBuilder("merge ");
 
 			// Check for FAST_FORWARD, ALREADY_UP_TO_DATE
@@ -134,7 +135,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 				RevCommit srcCommit = revWalk.lookupCommit(objectId);
 				if (revWalk.isMergedInto(srcCommit, headCommit)) {
 					setCallable(false);
-					return new MergeResult(headCommit,
+					return new MergeResult(headCommit, srcCommit,
+							new ObjectId[] { srcCommit, headCommit },
 							MergeStatus.ALREADY_UP_TO_DATE, mergeStrategy);
 				} else if (revWalk.isMergedInto(headCommit, srcCommit)) {
 					// FAST_FORWARD detected: skip doing a real merge but only
@@ -143,11 +145,14 @@ public class MergeCommand extends GitCommand<MergeResult> {
 					checkoutNewHead(revWalk, headCommit, srcCommit);
 					updateHead(refLogMessage, srcCommit, head.getObjectId());
 					setCallable(false);
-					return new MergeResult(srcCommit, MergeStatus.FAST_FORWARD,
-							mergeStrategy);
+					return new MergeResult(srcCommit, headCommit,
+							new ObjectId[] { srcCommit, headCommit },
+							MergeStatus.FAST_FORWARD, mergeStrategy);
 				} else {
 					return new MergeResult(
 							headCommit,
+							null,
+							new ObjectId[] { srcCommit, headCommit },
 							MergeResult.MergeStatus.NOT_SUPPORTED,
 							mergeStrategy,
 							JGitText.get().onlyAlreadyUpToDateAndFastForwardMergesAreAvailable);
@@ -164,7 +169,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 	}
 
 	private void checkoutNewHead(RevWalk revWalk, RevCommit headCommit,
-			RevCommit newHeadCommit) throws IOException, CheckoutConflictException {
+			RevCommit newHeadCommit) throws IOException,
+			CheckoutConflictException {
 		GitIndex index = repo.getIndex();
 
 		File workDir = repo.getWorkTree();
@@ -184,8 +190,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 		}
 	}
 
-	private void updateHead(StringBuilder refLogMessage,
-			ObjectId newHeadId, ObjectId oldHeadID) throws IOException,
+	private void updateHead(StringBuilder refLogMessage, ObjectId newHeadId,
+			ObjectId oldHeadID) throws IOException,
 			ConcurrentRefUpdateException {
 		RefUpdate refUpdate = repo.updateRef(Constants.HEAD);
 		refUpdate.setNewObjectId(newHeadId);
@@ -221,8 +227,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 
 	/**
 	 * @param commit
-	 *            a reference to a commit which is merged with the current
-	 *            head
+	 *            a reference to a commit which is merged with the current head
 	 * @return {@code this}
 	 */
 	public MergeCommand include(Ref commit) {
@@ -241,7 +246,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 	}
 
 	/**
-	 * @param name a name given to the commit
+	 * @param name
+	 *            a name given to the commit
 	 * @param commit
 	 *            the Id of a commit which is merged with the current head
 	 * @return {@code this}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
index a293ad0c95..6fcf2ee6d0 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
@@ -44,6 +44,7 @@
 package org.eclipse.jgit.api;
 
 import java.text.MessageFormat;
+import java.util.Map;
 
 import org.eclipse.jgit.JGitText;
 import org.eclipse.jgit.lib.ObjectId;
@@ -84,6 +85,12 @@ public class MergeResult {
 			}
 		},
 		/** */
+		CONFLICTING {
+			public String toString() {
+				return "Conflicting";
+			}
+		},
+		/** */
 		NOT_SUPPORTED {
 			public String toString() {
 				return "Not-yet-supported";
@@ -91,8 +98,14 @@ public class MergeResult {
 		}
 	}
 
+	private ObjectId[] mergedCommits;
+
+	private ObjectId base;
+
 	private ObjectId newHead;
 
+	private Map<String, int[][]> conflicts;
+
 	private MergeStatus mergeStatus;
 
 	private String description;
@@ -100,26 +113,47 @@ public class MergeResult {
 	private MergeStrategy mergeStrategy;
 
 	/**
-	 * @param newHead the object the head points at after the merge
-	 * @param mergeStatus the status the merge resulted in
-	 * @param mergeStrategy the used {@link MergeStrategy}
+	 * @param newHead
+	 *            the object the head points at after the merge
+	 * @param base
+	 *            the common base which was used to produce a content-merge. May
+	 *            be <code>null</code> if the merge-result was produced without
+	 *            computing a common base
+	 * @param mergedCommits
+	 *            all the commits which have been merged together
+	 * @param mergeStatus
+	 *            the status the merge resulted in
+	 * @param mergeStrategy
+	 *            the used {@link MergeStrategy}
 	 */
-	public MergeResult(ObjectId newHead, MergeStatus mergeStatus,
+	public MergeResult(ObjectId newHead, ObjectId base,
+			ObjectId[] mergedCommits, MergeStatus mergeStatus,
 			MergeStrategy mergeStrategy) {
-		this.newHead = newHead;
-		this.mergeStatus = mergeStatus;
-		this.mergeStrategy = mergeStrategy;
+		this(newHead, base, mergedCommits, mergeStatus, mergeStrategy, null);
 	}
 
 	/**
-	 * @param newHead the object the head points at after the merge
-	 * @param mergeStatus the status the merge resulted in
-	 * @param mergeStrategy the used {@link MergeStrategy}
-	 * @param description a user friendly description of the merge result
+	 * @param newHead
+	 *            the object the head points at after the merge
+	 * @param base
+	 *            the common base which was used to produce a content-merge. May
+	 *            be <code>null</code> if the merge-result was produced without
+	 *            computing a common base
+	 * @param mergedCommits
+	 *            all the commits which have been merged together
+	 * @param mergeStatus
+	 *            the status the merge resulted in
+	 * @param mergeStrategy
+	 *            the used {@link MergeStrategy}
+	 * @param description
+	 *            a user friendly description of the merge result
 	 */
-	public MergeResult(ObjectId newHead, MergeStatus mergeStatus,
+	public MergeResult(ObjectId newHead, ObjectId base,
+			ObjectId[] mergedCommits, MergeStatus mergeStatus,
 			MergeStrategy mergeStrategy, String description) {
 		this.newHead = newHead;
+		this.mergedCommits = mergedCommits;
+		this.base = base;
 		this.mergeStatus = mergeStatus;
 		this.mergeStrategy = mergeStrategy;
 		this.description = description;
@@ -139,12 +173,83 @@ public class MergeResult {
 		return mergeStatus;
 	}
 
+	/**
+	 * @return all the commits which have been merged together
+	 */
+	public ObjectId[] getMergedCommits() {
+		return mergedCommits;
+	}
+
+	/**
+	 * @return base the common base which was used to produce a content-merge.
+	 *         May be <code>null</code> if the merge-result was produced without
+	 *         computing a common base
+	 */
+	public ObjectId getBase() {
+		return base;
+	}
+
 	@Override
 	public String toString() {
+		boolean first = true;
+		StringBuilder commits = new StringBuilder();
+		for (ObjectId commit : mergedCommits) {
+			if (!first)
+				commits.append(", ");
+			else
+				first = false;
+			commits.append(ObjectId.toString(commit));
+		}
 		return MessageFormat.format(
 				JGitText.get().mergeUsingStrategyResultedInDescription,
-				mergeStrategy.getName(), mergeStatus, (description == null ? ""
-						: ", " + description));
+				commits, ObjectId.toString(base), mergeStrategy.getName(),
+				mergeStatus, (description == null ? "" : ", " + description));
 	}
 
+	/**
+	 * @param conflicts
+	 *            the conflicts to set
+	 */
+	public void setConflicts(Map<String, int[][]> conflicts) {
+		this.conflicts = conflicts;
+	}
+
+	/**
+	 * Returns information about the conflicts which occurred during a
+	 * {@link MergeCommand}. The returned value maps the path of a conflicting
+	 * file to a two-dimensional int-array of line-numbers telling where in the
+	 * file conflict markers for which merged commit can be found.
+	 * <p>
+	 * If the returned value contains a mapping "path"->[x][y]=z then this means
+	 * <ul>
+	 * <li>the file with path "path" contains conflicts</li>
+	 * <li>if y < "number of merged commits": for conflict number x in this file
+	 * the chunk which was copied from commit number y starts on line number z.
+	 * All numberings and line numbers start with 0.</li>
+	 * <li>if y == "number of merged commits": the first non-conflicting line
+	 * after conflict number x starts at line number z</li>
+	 * </ul>
+	 * <p>
+	 * Example code how to parse this data:
+	 * <pre> MergeResult m=...;
+	 * Map<String, int[][]> allConflicts = m.getConflicts();
+	 * for (String path : allConflicts.keySet()) {
+	 * 	int[][] c = allConflicts.get(path);
+	 * 	System.out.println("Conflicts in file " + path);
+	 * 	for (int i = 0; i < c.length; ++i) {
+	 * 		System.out.println("  Conflict #" + i);
+	 * 		for (int j = 0; j < (c[i].length) - 1; ++j) {
+	 * 			if (c[i][j] >= 0)
+	 * 				System.out.println("    Chunk for "
+	 * 						+ m.getMergedCommits()[j] + " starts on line #"
+	 * 						+ c[i][j]);
+	 * 		}
+	 * 	}
+	 * }</pre>
+	 *
+	 * @return the conflicts or <code>null</code> if no conflict occured
+	 */
+	public Map<String, int[][]> getConflicts() {
+		return conflicts;
+	}
 }