Extract 'Create Patch' into operation for reusability

In order to reuse the create patch functionality, it was extracted into
it's own operation, purely depending on JGit and decoupled from
FileDiff.

Also moved functionality for generating a filename for a specific commit
into the operation to be reusable. Tests added for the operation.

Change-Id: I6ce514ef020eacd42a94496dba80873b8e7f8743
Signed-off-by: Benjamin Muskalla <benjamin.muskalla@tasktop.com>

1 files changed, 208 insertions, 0 deletions

diff --git a/org.eclipse.egit.core/src/org/eclipse/egit/core/op/CreatePatchOperation.java b/org.eclipse.egit.core/src/org/eclipse/egit/core/op/CreatePatchOperation.java
new file mode 100644
index 0000000000..a5b91b49cd
--- /dev/null
+++ b/org.eclipse.egit.core/src/org/eclipse/egit/core/op/CreatePatchOperation.java
@@ -0,0 +1,208 @@
+/*******************************************************************************
+ * Copyright (c) 2010, SAP AG
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Stefan Lay (SAP AG) - initial implementation
+ *    Benjamin Muskalla (Tasktop Technologies) - extract into operation
+ *******************************************************************************/
+package org.eclipse.egit.core.op;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.text.SimpleDateFormat;
+import java.util.List;
+import java.util.Locale;
+
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.NullProgressMonitor;
+import org.eclipse.core.runtime.jobs.ISchedulingRule;
+import org.eclipse.egit.core.Activator;
+import org.eclipse.egit.core.CoreText;
+import org.eclipse.egit.core.EclipseGitProgressTransformer;
+import org.eclipse.egit.core.internal.CompareCoreUtils;
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
+import org.eclipse.jgit.diff.DiffEntry.ChangeType;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+
+/**
+ * Creates a patch for a specific commit
+ */
+public class CreatePatchOperation implements IEGitOperation {
+
+	private final RevCommit commit;
+
+	private final Repository repository;
+
+	private boolean useGitFormat = true;
+
+	// the encoding for the currently processed file
+	 private String currentEncoding = null;
+
+	private String patchContent;
+
+	/**
+	 * Creates the new operation.
+	 *
+	 * @param repository
+	 * @param commit
+	 */
+	public CreatePatchOperation(Repository repository, RevCommit commit) {
+		if (repository == null)
+			throw new IllegalArgumentException(
+					CoreText.CreatePatchOperation_repoRequired);
+		if (commit == null)
+			throw new IllegalArgumentException(
+					CoreText.CreatePatchOperation_commitRequired);
+		this.repository = repository;
+		this.commit = commit;
+	}
+
+	public void execute(IProgressMonitor monitor) throws CoreException {
+		EclipseGitProgressTransformer gitMonitor;
+		if (monitor == null)
+			gitMonitor = new EclipseGitProgressTransformer(
+					new NullProgressMonitor());
+		else
+			gitMonitor = new EclipseGitProgressTransformer(monitor);
+
+		final StringBuilder sb = new StringBuilder();
+		final DiffFormatter diffFmt = new DiffFormatter(
+				new ByteArrayOutputStream() {
+
+					@Override
+					public synchronized void write(byte[] b, int off, int len) {
+						super.write(b, off, len);
+						if (currentEncoding == null)
+							sb.append(toString());
+						else try {
+							sb.append(toString(currentEncoding));
+						} catch (UnsupportedEncodingException e) {
+							sb.append(toString());
+						}
+						reset();
+					}
+				});
+
+		diffFmt.setProgressMonitor(gitMonitor);
+
+		RevCommit[] parents = commit.getParents();
+		if (parents.length > 1)
+			throw new IllegalStateException(
+					"Cannot create patch for merge commit"); //$NON-NLS-1$
+
+		if (parents.length == 0)
+			throw new IllegalStateException(
+					"Cannot create patch for first commit"); //$NON-NLS-1$
+
+		if (useGitFormat)
+			writeGitPatchHeader(sb);
+
+		try {
+			diffFmt.setRepository(repository);
+			List<DiffEntry> diffs = diffFmt.scan(parents[0].getId(), commit.getId());
+			for (DiffEntry ent : diffs) {
+				String path;
+				if (ChangeType.DELETE.equals(ent.getChangeType()))
+					path = ent.getOldPath();
+				else
+					path = ent.getNewPath();
+				currentEncoding = CompareCoreUtils.getResourceEncoding(repository, path);
+				diffFmt.format(ent);
+			}
+		} catch (IOException e) {
+			Activator.logError("Patch file could not be written", e); //$NON-NLS-1$
+		}
+
+		patchContent = sb.toString();
+		// trim newline
+		if (patchContent.endsWith("\n")) //$NON-NLS-1$
+			patchContent = patchContent.substring(0, patchContent.length() - 1);
+	}
+
+	/**
+	 * Retrieves the content of the requested patch
+	 *
+	 * @return the content of the patch
+	 */
+	public String getPatchContent() {
+		if (patchContent == null)
+			throw new IllegalStateException(
+					"#execute needs to be called before this method."); //$NON-NLS-1$
+		return patchContent;
+	}
+
+	private void writeGitPatchHeader(StringBuilder sb) {
+		final SimpleDateFormat dtfmt;
+		dtfmt = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.US); //$NON-NLS-1$
+		dtfmt.setTimeZone(commit.getAuthorIdent().getTimeZone());
+		sb.append("From").append(" ") //$NON-NLS-1$ //$NON-NLS-2$
+				.append(commit.getId().getName()).append(" ") //$NON-NLS-1$
+				.append(dtfmt.format(Long.valueOf(System.currentTimeMillis())))
+				.append("\n"); //$NON-NLS-1$
+		sb.append("From") //$NON-NLS-1$
+				.append(": ") //$NON-NLS-1$
+				.append(commit.getAuthorIdent().getName())
+				.append(" <").append(commit.getAuthorIdent().getEmailAddress()) //$NON-NLS-1$
+				.append(">\n"); //$NON-NLS-1$
+		sb.append("Date").append(": ") //$NON-NLS-1$ //$NON-NLS-2$
+				.append(dtfmt.format(commit.getAuthorIdent().getWhen()))
+				.append("\n"); //$NON-NLS-1$
+		sb.append("Subject").append(": [PATCH] ") //$NON-NLS-1$ //$NON-NLS-2$
+				.append(commit.getShortMessage());
+
+		String message = commit.getFullMessage().substring(
+				commit.getShortMessage().length());
+		sb.append(message).append("\n\n"); //$NON-NLS-1$
+	}
+
+	/**
+	 * Decides whether to use the git format for patches.
+	 *
+	 * @param useFormat
+	 */
+	public void useGitFormat(boolean useFormat) {
+		this.useGitFormat = useFormat;
+	}
+
+	/**
+	 * Suggests a file name for the patch given the commit.
+	 *
+	 * @param commit
+	 * @return a file name for a patch
+	 */
+	public static String suggestFileName(RevCommit commit) {
+		String name = commit.getShortMessage();
+
+		name = name.trim();
+		StringBuilder filteredBuilder = new StringBuilder();
+		char[] charArray = name.toCharArray();
+		for (char c : charArray) {
+			if(Character.isLetter(c) || Character.isDigit(c))
+				filteredBuilder.append(c);
+			if(Character.isWhitespace(c) || c == '/')
+				filteredBuilder.append("-"); //$NON-NLS-1$
+		}
+		name = filteredBuilder.toString();
+		if (name.length() > 52)
+			name = name.substring(0, 52);
+		while (name.endsWith(".")) //$NON-NLS-1$
+			name = name.substring(0, name.length() - 1);
+		name = name.concat(".patch"); //$NON-NLS-1$
+
+		return name;
+	}
+
+	public ISchedulingRule getSchedulingRule() {
+		return null;
+	}
+
+}