/*
    * Copyright (C) 2007, Dave Watson <dwatson@mimvista.com>
    * Copyright (C) 2006-2007, Robin Rosenberg <robin.rosenberg@dewire.com>
    * Copyright (C) 2006-2007, Shawn O. Pearce <spearce@spearce.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.lib;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.Charset;
  import java.text.MessageFormat;
  import java.util.List;
  
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.util.References;
  
  /**
   * Mutable builder to construct a commit recording the state of a project.
   *
   * Applications should use this object when they need to manually construct a
   * commit and want precise control over its fields. For a higher level interface
   * see {@link org.eclipse.jgit.api.CommitCommand}.
   *
   * To read a commit object, construct a {@link org.eclipse.jgit.revwalk.RevWalk}
   * and obtain a {@link org.eclipse.jgit.revwalk.RevCommit} instance by calling
   * {@link org.eclipse.jgit.revwalk.RevWalk#parseCommit(AnyObjectId)}.
   */
  public class CommitBuilder {
  	private static final ObjectIdObjectId[] EMPTY_OBJECTID_LIST = new ObjectId[0];
  
  	private static final byte[] htree = Constants.encodeASCII("tree"); //$NON-NLS-1$
  
  	private static final byte[] hparent = Constants.encodeASCII("parent"); //$NON-NLS-1$
  
  	private static final byte[] hauthor = Constants.encodeASCII("author"); //$NON-NLS-1$
  
  	private static final byte[] hcommitter = Constants.encodeASCII("committer"); //$NON-NLS-1$
  
  	private static final byte[] hgpgsig = Constants.encodeASCII("gpgsig"); //$NON-NLS-1$
  
  	private static final byte[] hencoding = Constants.encodeASCII("encoding"); //$NON-NLS-1$
  
  	private ObjectId treeId;
  
  	private ObjectId[] parentIds;
  
  	private PersonIdent author;
  
  	private PersonIdent committer;
  
  	private GpgSignature gpgSignature;
  
  	private String message;
  
  	private Charset encoding;
  
  	/**
  	 * Initialize an empty commit.
  	 */
  	public CommitBuilder() {
  		parentIds = EMPTY_OBJECTID_LIST;
  		encoding = UTF_8;
  	}
  
  	/**
  	 * Get id of the root tree listing this commit's snapshot.
  	 *
  	 * @return id of the root tree listing this commit's snapshot.
  	 */
  	public ObjectId getTreeId() {
  		return treeId;
  	}
  
  	/**
  	 * Set the tree id for this commit object.
  	 *
  	 * @param id
  	 *            the tree identity.
  	 */
  	public void setTreeId(AnyObjectId id) {
  		treeId = id.copy();
  	}
  
  	/**
  	 * Get the author of this commit (who wrote it).
  	 *
  	 * @return the author of this commit (who wrote it).
 	 */
 	public PersonIdent getAuthor() {
 		return author;
 	}
 
 	/**
 	 * Set the author (name, email address, and date) of who wrote the commit.
 	 *
 	 * @param newAuthor
 	 *            the new author. Should not be null.
 	 */
 	public void setAuthor(PersonIdent newAuthor) {
 		author = newAuthor;
 	}
 
 	/**
 	 * Get the committer and commit time for this object.
 	 *
 	 * @return the committer and commit time for this object.
 	 */
 	public PersonIdent getCommitter() {
 		return committer;
 	}
 
 	/**
 	 * Set the committer and commit time for this object.
 	 *
 	 * @param newCommitter
 	 *            the committer information. Should not be null.
 	 */
 	public void setCommitter(PersonIdent newCommitter) {
 		committer = newCommitter;
 	}
 
 	/**
 	 * Set the GPG signature of this commit.
 	 * <p>
 	 * Note, the signature set here will change the payload of the commit, i.e.
 	 * the output of {@link #build()} will include the signature. Thus, the
 	 * typical flow will be:
 	 * <ol>
 	 * <li>call {@link #build()} without a signature set to obtain payload</li>
 	 * <li>create {@link GpgSignature} from payload</li>
 	 * <li>set {@link GpgSignature}</li>
 	 * </ol>
 	 * </p>
 	 *
 	 * @param newSignature
 	 *            the signature to set or <code>null</code> to unset
 	 * @since 5.3
 	 */
 	public void setGpgSignature(GpgSignature newSignature) {
 		gpgSignature = newSignature;
 	}
 
 	/**
 	 * Get the GPG signature of this commit.
 	 *
 	 * @return the GPG signature of this commit, maybe <code>null</code> if the
 	 *         commit is not to be signed
 	 * @since 5.3
 	 */
 	public GpgSignature getGpgSignature() {
 		return gpgSignature;
 	}
 
 	/**
 	 * Get the ancestors of this commit.
 	 *
 	 * @return the ancestors of this commit. Never null.
 	 */
 	public ObjectId[] getParentIds() {
 		return parentIds;
 	}
 
 	/**
 	 * Set the parent of this commit.
 	 *
 	 * @param newParent
 	 *            the single parent for the commit.
 	 */
 	public void setParentId(AnyObjectId newParent) {
 		parentIds = new ObjectId[] { newParent.copy() };
 	}
 
 	/**
 	 * Set the parents of this commit.
 	 *
 	 * @param parent1
 	 *            the first parent of this commit. Typically this is the current
 	 *            value of the {@code HEAD} reference and is thus the current
 	 *            branch's position in history.
 	 * @param parent2
 	 *            the second parent of this merge commit. Usually this is the
 	 *            branch being merged into the current branch.
 	 */
 	public void setParentIds(AnyObjectId./../../org/eclipse/jgit/lib/AnyObjectId.html#AnyObjectId">AnyObjectId parent1, AnyObjectId parent2) {
 		parentIds = new ObjectId[] { parent1.copy(), parent2.copy() };
 	}
 
 	/**
 	 * Set the parents of this commit.
 	 *
 	 * @param newParents
 	 *            the entire list of parents for this commit.
 	 */
 	public void setParentIds(ObjectId... newParents) {
 		parentIds = new ObjectId[newParents.length];
 		for (int i = 0; i < newParents.length; i++)
 			parentIds[i] = newParents[i].copy();
 	}
 
 	/**
 	 * Set the parents of this commit.
 	 *
 	 * @param newParents
 	 *            the entire list of parents for this commit.
 	 */
 	public void setParentIds(List<? extends AnyObjectId> newParents) {
 		parentIds = new ObjectId[newParents.size()];
 		for (int i = 0; i < newParents.size(); i++)
 			parentIds[i] = newParents.get(i).copy();
 	}
 
 	/**
 	 * Add a parent onto the end of the parent list.
 	 *
 	 * @param additionalParent
 	 *            new parent to add onto the end of the current parent list.
 	 */
 	public void addParentId(AnyObjectId additionalParent) {
 		if (parentIds.length == 0) {
 			setParentId(additionalParent);
 		} else {
 			ObjectId[] newParents = new ObjectId[parentIds.length + 1];
 			System.arraycopy(parentIds, 0, newParents, 0, parentIds.length);
 			newParents[parentIds.length] = additionalParent.copy();
 			parentIds = newParents;
 		}
 	}
 
 	/**
 	 * Get the complete commit message.
 	 *
 	 * @return the complete commit message.
 	 */
 	public String getMessage() {
 		return message;
 	}
 
 	/**
 	 * Set the commit message.
 	 *
 	 * @param newMessage
 	 *            the commit message. Should not be null.
 	 */
 	public void setMessage(String newMessage) {
 		message = newMessage;
 	}
 
 	/**
 	 * Set the encoding for the commit information.
 	 *
 	 * @param encodingName
 	 *            the encoding name. See
 	 *            {@link java.nio.charset.Charset#forName(String)}.
 	 * @deprecated use {@link #setEncoding(Charset)} instead.
 	 */
 	@Deprecated
 	public void setEncoding(String encodingName) {
 		encoding = Charset.forName(encodingName);
 	}
 
 	/**
 	 * Set the encoding for the commit information.
 	 *
 	 * @param enc
 	 *            the encoding to use.
 	 */
 	public void setEncoding(Charset enc) {
 		encoding = enc;
 	}
 
 	/**
 	 * Get the encoding that should be used for the commit message text.
 	 *
 	 * @return the encoding that should be used for the commit message text.
 	 */
 	public Charset getEncoding() {
 		return encoding;
 	}
 
 	/**
 	 * Format this builder's state as a commit object.
 	 *
 	 * @return this object in the canonical commit format, suitable for storage
 	 *         in a repository.
 	 * @throws java.io.UnsupportedEncodingException
 	 *             the encoding specified by {@link #getEncoding()} is not
 	 *             supported by this Java runtime.
 	 */
 	public byte[] build() throws UnsupportedEncodingException {
 		ByteArrayOutputStream os = new ByteArrayOutputStream();
 		OutputStreamWriter w = new OutputStreamWriter(os, getEncoding());
 		try {
 			os.write(htree);
 			os.write(' ');
 			getTreeId().copyTo(os);
 			os.write('\n');
 
 			for (ObjectId p : getParentIds()) {
 				os.write(hparent);
 				os.write(' ');
 				p.copyTo(os);
 				os.write('\n');
 			}
 
 			os.write(hauthor);
 			os.write(' ');
 			w.write(getAuthor().toExternalString());
 			w.flush();
 			os.write('\n');
 
 			os.write(hcommitter);
 			os.write(' ');
 			w.write(getCommitter().toExternalString());
 			w.flush();
 			os.write('\n');
 
 			if (getGpgSignature() != null) {
 				os.write(hgpgsig);
 				os.write(' ');
 				writeGpgSignatureString(getGpgSignature().toExternalString(), os);
 				os.write('\n');
 			}
 
 			if (!References.isSameObject(getEncoding(), UTF_8)) {
 				os.write(hencoding);
 				os.write(' ');
 				os.write(Constants.encodeASCII(getEncoding().name()));
 				os.write('\n');
 			}
 
 			os.write('\n');
 
 			if (getMessage() != null) {
 				w.write(getMessage());
 				w.flush();
 			}
 		} catch (IOException err) {
 			// This should never occur, the only way to get it above is
 			// for the ByteArrayOutputStream to throw, but it doesn't.
 			//
 			throw new RuntimeException(err);
 		}
 		return os.toByteArray();
 	}
 
 	/**
 	 * Writes signature to output as per <a href=
 	 * "https://github.com/git/git/blob/master/Documentation/technical/signature-format.txt#L66,L89">gpgsig
 	 * header</a>.
 	 * <p>
 	 * CRLF and CR will be sanitized to LF and signature will have a hanging
 	 * indent of one space starting with line two. A trailing line break is
 	 * <em>not</em> written; the caller is supposed to terminate the GPG
 	 * signature header by writing a single newline.
 	 * </p>
 	 *
 	 * @param in
 	 *            signature string with line breaks
 	 * @param out
 	 *            output stream
 	 * @throws IOException
 	 *             thrown by the output stream
 	 * @throws IllegalArgumentException
 	 *             if the signature string contains non 7-bit ASCII chars
 	 */
 	static void writeGpgSignatureString(String in, OutputStream out)
 			throws IOException, IllegalArgumentException {
 		int length = in.length();
 		for (int i = 0; i < length; ++i) {
 			char ch = in.charAt(i);
 			switch (ch) {
 			case '\r':
 				if (i + 1 < length && in.charAt(i + 1) == '\n') {
 					++i;
 				}
 				if (i + 1 < length) {
 					out.write('\n');
 					out.write(' ');
 				}
 				break;
 			case '\n':
 				if (i + 1 < length) {
 					out.write('\n');
 					out.write(' ');
 				}
 				break;
 			default:
 				// sanity check
 				if (ch > 127)
 					throw new IllegalArgumentException(MessageFormat
 							.format(JGitText.get().notASCIIString, in));
 				out.write(ch);
 				break;
 			}
 		}
 	}
 
 	/**
 	 * Format this builder's state as a commit object.
 	 *
 	 * @return this object in the canonical commit format, suitable for storage
 	 *         in a repository.
 	 * @throws java.io.UnsupportedEncodingException
 	 *             the encoding specified by {@link #getEncoding()} is not
 	 *             supported by this Java runtime.
 	 */
 	public byte[] toByteArray() throws UnsupportedEncodingException {
 		return build();
 	}
 
 	/** {@inheritDoc} */
 	@SuppressWarnings("nls")
 	@Override
 	public String toString() {
 		StringBuilder r = new StringBuilder();
 		r.append("Commit");
 		r.append("={\n");
 
 		r.append("tree ");
 		r.append(treeId != null ? treeId.name() : "NOT_SET");
 		r.append("\n");
 
 		for (ObjectId p : parentIds) {
 			r.append("parent ");
 			r.append(p.name());
 			r.append("\n");
 		}
 
 		r.append("author ");
 		r.append(author != null ? author.toString() : "NOT_SET");
 		r.append("\n");
 
 		r.append("committer ");
 		r.append(committer != null ? committer.toString() : "NOT_SET");
 		r.append("\n");
 
 		r.append("gpgSignature ");
 		r.append(gpgSignature != null ? gpgSignature.toString() : "NOT_SET");
 		r.append("\n");
 
 		if (encoding != null && !References.isSameObject(encoding, UTF_8)) {
 			r.append("encoding ");
 			r.append(encoding.name());
 			r.append("\n");
 		}
 
 		r.append("\n");
 		r.append(message != null ? message : "");
 		r.append("}");
 		return r.toString();
 	}
 }