/*
    * Copyright (C) 2008-2009, Google Inc.
    * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
    * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.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.revwalk;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.IllegalCharsetNameException;
  import java.nio.charset.UnsupportedCharsetException;
  
  import org.eclipse.jgit.errors.CorruptObjectException;
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.ObjectInserter;
  import org.eclipse.jgit.lib.ObjectReader;
  import org.eclipse.jgit.lib.PersonIdent;
  import org.eclipse.jgit.util.MutableInteger;
  import org.eclipse.jgit.util.RawParseUtils;
  import org.eclipse.jgit.util.StringUtils;
  
  /** An annotated tag. */
  public class RevTag extends RevObject {
  	/**
  	 * Parse an annotated tag from its canonical format.
  	 *
  	 * This method constructs a temporary revision pool, parses the tag as
  	 * supplied, and returns it to the caller. Since the tag was built inside of
  	 * a private revision pool its object pointer will be initialized, but will
  	 * not have its headers loaded.
  	 *
  	 * Applications are discouraged from using this API. Callers usually need
  	 * more than one object. Use {@link RevWalk#parseTag(AnyObjectId)} to obtain
  	 * a RevTag from an existing repository.
  	 *
  	 * @param raw
  	 *            the canonical formatted tag to be parsed.
  	 * @return the parsed tag, in an isolated revision pool that is not
  	 *         available to the caller.
  	 * @throws CorruptObjectException
  	 *             the tag contains a malformed header that cannot be handled.
  	 */
  	public static RevTag parse(byte[] raw) throws CorruptObjectException {
  		return parse(new RevWalk((ObjectReader) null), raw);
  	}
  
  	/**
  	 * Parse an annotated tag from its canonical format.
  	 * <p>
  	 * This method inserts the tag directly into the caller supplied revision
  	 * pool, making it appear as though the tag exists in the repository, even
  	 * if it doesn't. The repository under the pool is not affected.
  	 * <p>
  	 * The body of the tag (message, tagger, signature) is always retained in
 	 * the returned {@code RevTag}, even if the supplied {@code RevWalk} has
 	 * been configured with {@code setRetainBody(false)}.
 	 *
 	 * @param rw
 	 *            the revision pool to allocate the tag within. The tag's object
 	 *            pointer will be obtained from this pool.
 	 * @param raw
 	 *            the canonical formatted tag to be parsed. This buffer will be
 	 *            retained by the returned {@code RevTag} and must not be
 	 *            modified by the caller.
 	 * @return the parsed tag, in an isolated revision pool that is not
 	 *         available to the caller.
 	 * @throws CorruptObjectException
 	 *             the tag contains a malformed header that cannot be handled.
 	 */
 	public static RevTag parse(RevWalk rw, byte[] raw)
 			throws CorruptObjectException {
 		try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
 			RevTag r = rw.lookupTag(fmt.idFor(Constants.OBJ_TAG, raw));
 			r.parseCanonical(rw, raw);
 			r.buffer = raw;
 			return r;
 		}
 	}
 
 	private RevObject object;
 
 	private byte[] buffer;
 
 	private String tagName;
 
 	/**
 	 * Create a new tag reference.
 	 *
 	 * @param id
 	 *            object name for the tag.
 	 */
 	protected RevTag(final AnyObjectId id) {
 		super(id);
 	}
 
 	@Override
 	void parseHeaders(final RevWalk walk) throws MissingObjectException,
 			IncorrectObjectTypeException, IOException {
 		parseCanonical(walk, walk.getCachedBytes(this));
 	}
 
 	@Override
 	void parseBody(final RevWalk walk) throws MissingObjectException,
 			IncorrectObjectTypeException, IOException {
 		if (buffer == null) {
 			buffer = walk.getCachedBytes(this);
 			if ((flags & PARSED) == 0)
 				parseCanonical(walk, buffer);
 		}
 	}
 
 	void parseCanonical(final RevWalk walk, final byte[] rawTag)
 			throws CorruptObjectException {
 		final MutableInteger pos = new MutableInteger();
 		final int oType;
 
 		pos.value = 53; // "object $sha1\ntype "
 		oType = Constants.decodeTypeString(this, rawTag, (byte) '\n', pos);
 		walk.idBuffer.fromString(rawTag, 7);
 		object = walk.lookupAny(walk.idBuffer, oType);
 
 		int p = pos.value += 4; // "tag "
 		final int nameEnd = RawParseUtils.nextLF(rawTag, p) - 1;
 		tagName = RawParseUtils.decode(UTF_8, rawTag, p, nameEnd);
 
 		if (walk.isRetainBody())
 			buffer = rawTag;
 		flags |= PARSED;
 	}
 
 	@Override
 	public final int getType() {
 		return Constants.OBJ_TAG;
 	}
 
 	/**
 	 * Parse the tagger identity from the raw buffer.
 	 * <p>
 	 * This method parses and returns the content of the tagger line, after
 	 * taking the tag's character set into account and decoding the tagger
 	 * name and email address. This method is fairly expensive and produces a
 	 * new PersonIdent instance on each invocation. Callers should invoke this
 	 * method only if they are certain they will be outputting the result, and
 	 * should cache the return value for as long as necessary to use all
 	 * information from it.
 	 *
 	 * @return identity of the tagger (name, email) and the time the tag
 	 *         was made by the tagger; null if no tagger line was found.
 	 */
 	public final PersonIdent getTaggerIdent() {
 		final byte[] raw = buffer;
 		final int nameB = RawParseUtils.tagger(raw, 0);
 		if (nameB < 0)
 			return null;
 		return RawParseUtils.parsePersonIdent(raw, nameB);
 	}
 
 	/**
 	 * Parse the complete tag message and decode it to a string.
 	 * <p>
 	 * This method parses and returns the message portion of the tag buffer,
 	 * after taking the tag's character set into account and decoding the buffer
 	 * using that character set. This method is a fairly expensive operation and
 	 * produces a new string on each invocation.
 	 *
 	 * @return decoded tag message as a string. Never null.
 	 */
 	public final String getFullMessage() {
 		byte[] raw = buffer;
 		int msgB = RawParseUtils.tagMessage(raw, 0);
 		if (msgB < 0) {
 			return ""; //$NON-NLS-1$
 		}
 		return RawParseUtils.decode(guessEncoding(), raw, msgB, raw.length);
 	}
 
 	/**
 	 * Parse the tag message and return the first "line" of it.
 	 * <p>
 	 * The first line is everything up to the first pair of LFs. This is the
 	 * "oneline" format, suitable for output in a single line display.
 	 * <p>
 	 * This method parses and returns the message portion of the tag buffer,
 	 * after taking the tag's character set into account and decoding the buffer
 	 * using that character set. This method is a fairly expensive operation and
 	 * produces a new string on each invocation.
 	 *
 	 * @return decoded tag message as a string. Never null. The returned string
 	 *         does not contain any LFs, even if the first paragraph spanned
 	 *         multiple lines. Embedded LFs are converted to spaces.
 	 */
 	public final String getShortMessage() {
 		byte[] raw = buffer;
 		int msgB = RawParseUtils.tagMessage(raw, 0);
 		if (msgB < 0) {
 			return ""; //$NON-NLS-1$
 		}
 
 		int msgE = RawParseUtils.endOfParagraph(raw, msgB);
 		String str = RawParseUtils.decode(guessEncoding(), raw, msgB, msgE);
 		if (RevCommit.hasLF(raw, msgB, msgE)) {
 			str = StringUtils.replaceLineBreaksWithSpace(str);
 		}
 		return str;
 	}
 
 	private Charset guessEncoding() {
 		try {
 			return RawParseUtils.parseEncoding(buffer);
 		} catch (IllegalCharsetNameException | UnsupportedCharsetException e) {
 			return UTF_8;
 		}
 	}
 
 	/**
 	 * Get a reference to the object this tag was placed on.
 	 * <p>
 	 * Note that the returned object has only been looked up (see
 	 * {@link RevWalk#lookupAny(AnyObjectId, int)}. To access the contents it
 	 * needs to be parsed, see {@link RevWalk#parseHeaders(RevObject)} and
 	 * {@link RevWalk#parseBody(RevObject)}.
 	 * <p>
 	 * As an alternative, use {@link RevWalk#peel(RevObject)} and pass this
 	 * {@link RevTag} to peel it until the first non-tag object.
 	 *
 	 * @return object this tag refers to (only looked up, not parsed)
 	 */
 	public final RevObject getObject() {
 		return object;
 	}
 
 	/**
 	 * Get the name of this tag, from the tag header.
 	 *
 	 * @return name of the tag, according to the tag header.
 	 */
 	public final String getTagName() {
 		return tagName;
 	}
 
 	/**
 	 * Discard the message buffer to reduce memory usage.
 	 * <p>
 	 * After discarding the memory usage of the {@code RevTag} is reduced to
 	 * only the {@link #getObject()} pointer and {@link #getTagName()}.
 	 * Accessing other properties such as {@link #getTaggerIdent()} or either
 	 * message function requires reloading the buffer by invoking
 	 * {@link RevWalk#parseBody(RevObject)}.
 	 *
 	 * @since 4.0
 	 */
 	public final void disposeBody() {
 		buffer = null;
 	}
 }