Provide git config commit.cleanup

Add an enumeration for the possible values, and a method to resolve the
"default" value. Give CommitConfig a static method to process a text
according to a given clean-up mode and comment character.

(The core.commentChar is not yet handled by JGit; it's hard-coded as #.)

Bug: 553065
Change-Id: If6e384522275f73b713fbc29ffcaa1753c239dea
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

2 files changed, 187 insertions, 0 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/CommitConfig.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/CommitConfig.java
index 22e1f98181..55cc02683a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/CommitConfig.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/CommitConfig.java
@@ -18,11 +18,13 @@ import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.StandardCharsets;
 import java.nio.charset.UnsupportedCharsetException;
 import java.text.MessageFormat;
+import java.util.Locale;
 
 import org.eclipse.jgit.annotations.NonNull;
 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.lib.Config.ConfigEnum;
 import org.eclipse.jgit.lib.Config.SectionParser;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.IO;
@@ -34,22 +36,76 @@ import org.eclipse.jgit.util.RawParseUtils;
  * @since 5.13
  */
 public class CommitConfig {
+
 	/**
 	 * Key for {@link Config#get(SectionParser)}.
 	 */
 	public static final Config.SectionParser<CommitConfig> KEY = CommitConfig::new;
 
+	private static final String CUT = " ------------------------ >8 ------------------------\n"; //$NON-NLS-1$
+
+	/**
+	 * How to clean up commit messages when committing.
+	 *
+	 * @since 6.1
+	 */
+	public enum CleanupMode implements ConfigEnum {
+
+		/**
+		 * {@link #WHITESPACE}, additionally remove comment lines.
+		 */
+		STRIP,
+
+		/**
+		 * Remove trailing whitespace and leading and trailing empty lines;
+		 * collapse multiple empty lines to a single one.
+		 */
+		WHITESPACE,
+
+		/**
+		 * Make no changes.
+		 */
+		VERBATIM,
+
+		/**
+		 * Omit everything from the first "scissor" line on, then apply
+		 * {@link #WHITESPACE}.
+		 */
+		SCISSORS,
+
+		/**
+		 * Use {@link #STRIP} for user-edited messages, otherwise
+		 * {@link #WHITESPACE}, unless overridden by a git config setting other
+		 * than DEFAULT.
+		 */
+		DEFAULT;
+
+		@Override
+		public String toConfigValue() {
+			return name().toLowerCase(Locale.ROOT);
+		}
+
+		@Override
+		public boolean matchConfigValue(String in) {
+			return toConfigValue().equals(in);
+		}
+	}
+
 	private final static Charset DEFAULT_COMMIT_MESSAGE_ENCODING = StandardCharsets.UTF_8;
 
 	private String i18nCommitEncoding;
 
 	private String commitTemplatePath;
 
+	private CleanupMode cleanupMode;
+
 	private CommitConfig(Config rc) {
 		commitTemplatePath = rc.getString(ConfigConstants.CONFIG_COMMIT_SECTION,
 				null, ConfigConstants.CONFIG_KEY_COMMIT_TEMPLATE);
 		i18nCommitEncoding = rc.getString(ConfigConstants.CONFIG_SECTION_I18N,
 				null, ConfigConstants.CONFIG_KEY_COMMIT_ENCODING);
+		cleanupMode = rc.getEnum(ConfigConstants.CONFIG_COMMIT_SECTION, null,
+				ConfigConstants.CONFIG_KEY_CLEANUP, CleanupMode.DEFAULT);
 	}
 
 	/**
@@ -75,6 +131,48 @@ public class CommitConfig {
 	}
 
 	/**
+	 * Retrieves the {@link CleanupMode} as given by git config
+	 * {@code commit.cleanup}.
+	 *
+	 * @return the {@link CleanupMode}; {@link CleanupMode#DEFAULT} if the git
+	 *         config is not set
+	 * @since 6.1
+	 */
+	@NonNull
+	public CleanupMode getCleanupMode() {
+		return cleanupMode;
+	}
+
+	/**
+	 * Computes a non-default {@link CleanupMode} from the given mode and the
+	 * git config.
+	 *
+	 * @param mode
+	 *            {@link CleanupMode} to resolve
+	 * @param defaultStrip
+	 *            if {@code true} return {@link CleanupMode#STRIP} if the git
+	 *            config is also "default", otherwise return
+	 *            {@link CleanupMode#WHITESPACE}
+	 * @return the {@code mode}, if it is not {@link CleanupMode#DEFAULT},
+	 *         otherwise the resolved mode, which is never
+	 *         {@link CleanupMode#DEFAULT}
+	 * @since 6.1
+	 */
+	@NonNull
+	public CleanupMode resolve(@NonNull CleanupMode mode,
+			boolean defaultStrip) {
+		if (CleanupMode.DEFAULT == mode) {
+			CleanupMode defaultMode = getCleanupMode();
+			if (CleanupMode.DEFAULT == defaultMode) {
+				return defaultStrip ? CleanupMode.STRIP
+						: CleanupMode.WHITESPACE;
+			}
+			return defaultMode;
+		}
+		return mode;
+	}
+
+	/**
 	 * Get the content to the commit template as defined in
 	 * {@code commit.template}. If no {@code i18n.commitEncoding} is specified,
 	 * UTF-8 fallback is used.
@@ -135,4 +233,86 @@ public class CommitConfig {
 
 		return commitMessageEncoding;
 	}
+
+	/**
+	 * Processes a text according to the given {@link CleanupMode}.
+	 *
+	 * @param text
+	 *            text to process
+	 * @param mode
+	 *            {@link CleanupMode} to use
+	 * @param commentChar
+	 *            comment character (normally {@code #}) to use if {@code mode}
+	 *            is {@link CleanupMode#STRIP} or {@link CleanupMode#SCISSORS}
+	 * @return the processed text
+	 * @throws IllegalArgumentException
+	 *             if {@code mode} is {@link CleanupMode#DEFAULT} (use
+	 *             {@link #resolve(CleanupMode, boolean)} first)
+	 * @since 6.1
+	 */
+	public static String cleanText(@NonNull String text,
+			@NonNull CleanupMode mode, char commentChar) {
+		String toProcess = text;
+		boolean strip = false;
+		switch (mode) {
+		case VERBATIM:
+			return text;
+		case SCISSORS:
+			String cut = commentChar + CUT;
+			if (text.startsWith(cut)) {
+				return ""; //$NON-NLS-1$
+			}
+			int cutPos = text.indexOf('\n' + cut);
+			if (cutPos >= 0) {
+				toProcess = text.substring(0, cutPos + 1);
+			}
+			break;
+		case STRIP:
+			strip = true;
+			break;
+		case WHITESPACE:
+			break;
+		case DEFAULT:
+		default:
+			// Internal error; no translation
+			throw new IllegalArgumentException("Invalid clean-up mode " + mode); //$NON-NLS-1$
+		}
+		// WHITESPACE
+		StringBuilder result = new StringBuilder();
+		boolean lastWasEmpty = true;
+		for (String line : toProcess.split("\n")) { //$NON-NLS-1$
+			line = line.stripTrailing();
+			if (line.isEmpty()) {
+				if (!lastWasEmpty) {
+					result.append('\n');
+					lastWasEmpty = true;
+				}
+			} else if (!strip || !isComment(line, commentChar)) {
+				lastWasEmpty = false;
+				result.append(line).append('\n');
+			}
+		}
+		int bufferSize = result.length();
+		if (lastWasEmpty && bufferSize > 0) {
+			bufferSize--;
+			result.setLength(bufferSize);
+		}
+		if (bufferSize > 0 && !toProcess.endsWith("\n")) { //$NON-NLS-1$
+			if (result.charAt(bufferSize - 1) == '\n') {
+				result.setLength(bufferSize - 1);
+			}
+		}
+		return result.toString();
+	}
+
+	private static boolean isComment(String text, char commentChar) {
+		int len = text.length();
+		for (int i = 0; i < len; i++) {
+			char ch = text.charAt(i);
+			if (!Character.isWhitespace(ch)) {
+				return ch == commentChar;
+			}
+		}
+		return false;
+	}
 }
\ No newline at end of file
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
index 4b21e4be4e..af2b4ccdd1 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
@@ -182,6 +182,13 @@ public final class ConfigConstants {
 	public static final String CONFIG_TAG_SECTION = "tag";
 
 	/**
+	 * The "cleanup" key
+	 *
+	 * @since 6.1
+	 */
+	public static final String CONFIG_KEY_CLEANUP = "cleanup";
+
+	/**
 	 * The "gpgSign" key
 	 *
 	 * @since 5.2