/*
 * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com>
 * 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.api;

import java.io.IOException;
import java.io.InputStream;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import org.eclipse.jgit.JGitText;
import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
import org.eclipse.jgit.api.errors.JGitInternalException;
import org.eclipse.jgit.api.errors.NoFilepatternException;
import org.eclipse.jgit.api.errors.NoHeadException;
import org.eclipse.jgit.api.errors.NoMessageException;
import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
import org.eclipse.jgit.dircache.DirCache;
import org.eclipse.jgit.dircache.DirCacheBuilder;
import org.eclipse.jgit.dircache.DirCacheEditor;
import org.eclipse.jgit.dircache.DirCacheEditor.DeletePath;
import org.eclipse.jgit.dircache.DirCacheEditor.PathEdit;
import org.eclipse.jgit.dircache.DirCacheEntry;
import org.eclipse.jgit.dircache.DirCacheIterator;
import org.eclipse.jgit.errors.UnmergedPathException;
import org.eclipse.jgit.lib.CommitBuilder;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.lib.PersonIdent;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.RefUpdate;
import org.eclipse.jgit.lib.RefUpdate.Result;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.lib.RepositoryState;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.CanonicalTreeParser;
import org.eclipse.jgit.treewalk.FileTreeIterator;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.util.ChangeIdUtil;

/**
 * A class used to execute a {@code Commit} command. It has setters for all
 * supported options and arguments of this command and a {@link #call()} method
 * to finally execute the command.
 *
 * @see <a
 *      href="http://www.kernel.org/pub/software/scm/git/docs/git-commit.html"
 *      >Git documentation about Commit</a>
 */
public class CommitCommand extends GitCommand<RevCommit> {
	private PersonIdent author;

	private PersonIdent committer;

	private String message;

	private boolean all;

	private List<String> only = new ArrayList<String>();

	private boolean[] onlyProcessed;

	private boolean amend;

	private boolean insertChangeId;

	/**
	 * parents this commit should have. The current HEAD will be in this list
	 * and also all commits mentioned in .git/MERGE_HEAD
	 */
	private List<ObjectId> parents = new LinkedList<ObjectId>();

	private String reflogComment;

	/**
	 * @param repo
	 */
	protected CommitCommand(Repository repo) {
		super(repo);
	}

	/**
	 * Executes the {@code commit} command with all the options and parameters
	 * collected by the setter methods of this class. Each instance of this
	 * class should only be used for one invocation of the command (means: one
	 * call to {@link #call()})
	 *
	 * @return a {@link RevCommit} object representing the successful commit.
	 * @throws NoHeadException
	 *             when called on a git repo without a HEAD reference
	 * @throws NoMessageException
	 *             when called without specifying a commit message
	 * @throws UnmergedPathException
	 *             when the current index contained unmerged paths (conflicts)
	 * @throws WrongRepositoryStateException
	 *             when repository is not in the right state for committing
	 * @throws JGitInternalException
	 *             a low-level exception of JGit has occurred. The original
	 *             exception can be retrieved by calling
	 *             {@link Exception#getCause()}. Expect only
	 *             {@code IOException's} to be wrapped. Subclasses of
	 *             {@link IOException} (e.g. {@link UnmergedPathException}) are
	 *             typically not wrapped here but thrown as original exception
	 */
	public RevCommit call() throws NoHeadException, NoMessageException,
			UnmergedPathException, ConcurrentRefUpdateException,
			JGitInternalException, WrongRepositoryStateException {
		checkCallable();

		RepositoryState state = repo.getRepositoryState();
		if (!state.canCommit())
			throw new WrongRepositoryStateException(MessageFormat.format(
					JGitText.get().cannotCommitOnARepoWithState, state.name()));
		processOptions(state);

		try {
			if (all && !repo.isBare() && repo.getWorkTree() != null) {
				Git git = new Git(repo);
				try {
					git.add()
							.addFilepattern(".")
							.setUpdate(true).call();
				} catch (NoFilepatternException e) {
					// should really not happen
					throw new JGitInternalException(e.getMessage(), e);
				}
			}

			Ref head = repo.getRef(Constants.HEAD);
			if (head == null)
				throw new NoHeadException(
						JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);

			// determine the current HEAD and the commit it is referring to
			ObjectId headId = repo.resolve(Constants.HEAD + "^{commit}");
			if (headId != null)
				if (amend) {
					RevCommit previousCommit = new RevWalk(repo)
							.parseCommit(headId);
					RevCommit[] p = previousCommit.getParents();
					for (int i = 0; i < p.length; i++)
						parents.add(0, p[i].getId());
				} else {
					parents.add(0, headId);
				}

			// lock the index
			DirCache index = repo.lockDirCache();
			try {
				if (!only.isEmpty())
					index = createTemporaryIndex(headId, index);

				ObjectInserter odi = repo.newObjectInserter();
				try {
					// Write the index as tree to the object database. This may
					// fail for example when the index contains unmerged paths
					// (unresolved conflicts)
					ObjectId indexTreeId = index.writeTree(odi);

					if (insertChangeId)
						insertChangeId(indexTreeId);

					// Create a Commit object, populate it and write it
					CommitBuilder commit = new CommitBuilder();
					commit.setCommitter(committer);
					commit.setAuthor(author);
					commit.setMessage(message);

					commit.setParentIds(parents);
					commit.setTreeId(indexTreeId);
					ObjectId commitId = odi.insert(commit);
					odi.flush();

					RevWalk revWalk = new RevWalk(repo);
					try {
						RevCommit revCommit = revWalk.parseCommit(commitId);
						RefUpdate ru = repo.updateRef(Constants.HEAD);
						ru.setNewObjectId(commitId);
						if (reflogComment != null) {
							ru.setRefLogMessage(reflogComment, false);
						} else {
							String prefix = amend ? "commit (amend): "
									: "commit: ";
							ru.setRefLogMessage(
									prefix + revCommit.getShortMessage(), false);
						}
						if (headId != null)
							ru.setExpectedOldObjectId(headId);
						else
							ru.setExpectedOldObjectId(ObjectId.zeroId());
						Result rc = ru.forceUpdate();
						switch (rc) {
						case NEW:
						case FORCED:
						case FAST_FORWARD: {
							setCallable(false);
							if (state == RepositoryState.MERGING_RESOLVED) {
								// Commit was successful. Now delete the files
								// used for merge commits
								repo.writeMergeCommitMsg(null);
								repo.writeMergeHeads(null);
							} else if (state == RepositoryState.CHERRY_PICKING_RESOLVED) {
								repo.writeMergeCommitMsg(null);
								repo.writeCherryPickHead(null);
							}
							return revCommit;
						}
						case REJECTED:
						case LOCK_FAILURE:
							throw new ConcurrentRefUpdateException(JGitText
									.get().couldNotLockHEAD, ru.getRef(), rc);
						default:
							throw new JGitInternalException(MessageFormat
									.format(JGitText.get().updatingRefFailed,
											Constants.HEAD,
											commitId.toString(), rc));
						}
					} finally {
						revWalk.release();
					}
				} finally {
					odi.release();
				}
			} finally {
				index.unlock();
			}
		} catch (UnmergedPathException e) {
			// since UnmergedPathException is a subclass of IOException
			// which should not be wrapped by a JGitInternalException we
			// have to catch and re-throw it here
			throw e;
		} catch (IOException e) {
			throw new JGitInternalException(
					JGitText.get().exceptionCaughtDuringExecutionOfCommitCommand, e);
		}
	}

	private void insertChangeId(ObjectId treeId) throws IOException {
		ObjectId firstParentId = null;
		if (!parents.isEmpty())
			firstParentId = parents.get(0);
		ObjectId changeId = ChangeIdUtil.computeChangeId(treeId, firstParentId,
				author, committer, message);
		message = ChangeIdUtil.insertId(message, changeId);
		if (changeId != null)
			message = message.replaceAll("\nChange-Id: I"
					+ ObjectId.zeroId().getName() + "\n", "\nChange-Id: I"
					+ changeId.getName() + "\n");
	}

	private DirCache createTemporaryIndex(ObjectId headId, DirCache index)
			throws IOException {
		ObjectInserter inserter = null;

		// get DirCacheEditor to modify the index if required
		DirCacheEditor dcEditor = index.editor();

		// get DirCacheBuilder for newly created in-core index to build a
		// temporary index for this commit
		DirCache inCoreIndex = DirCache.newInCore();
		DirCacheBuilder dcBuilder = inCoreIndex.builder();

		onlyProcessed = new boolean[only.size()];
		boolean emptyCommit = true;

		TreeWalk treeWalk = new TreeWalk(repo);
		int dcIdx = treeWalk.addTree(new DirCacheIterator(index));
		int fIdx = treeWalk.addTree(new FileTreeIterator(repo));
		int hIdx = -1;
		if (headId != null)
			hIdx = treeWalk.addTree(new RevWalk(repo).parseTree(headId));
		treeWalk.setRecursive(true);

		while (treeWalk.next()) {
			String path = treeWalk.getPathString();
			// check if current entry's path matches a specified path
			int pos = lookupOnly(path);

			CanonicalTreeParser hTree = null;
			if (hIdx != -1)
				hTree = treeWalk.getTree(hIdx, CanonicalTreeParser.class);

			if (pos >= 0) {
				// include entry in commit

				DirCacheIterator dcTree = treeWalk.getTree(dcIdx,
						DirCacheIterator.class);
				FileTreeIterator fTree = treeWalk.getTree(fIdx,
						FileTreeIterator.class);

				// check if entry refers to a tracked file
				boolean tracked = dcTree != null || hTree != null;
				if (!tracked)
					break;

				if (fTree != null) {
					// create a new DirCacheEntry with data retrieved from disk
					final DirCacheEntry dcEntry = new DirCacheEntry(path);
					long entryLength = fTree.getEntryLength();
					dcEntry.setLength(entryLength);
					dcEntry.setLastModified(fTree.getEntryLastModified());
					dcEntry.setFileMode(fTree.getIndexFileMode(dcTree));

					boolean objectExists = (dcTree != null && fTree
							.idEqual(dcTree))
							|| (hTree != null && fTree.idEqual(hTree));
					if (objectExists) {
						dcEntry.setObjectId(fTree.getEntryObjectId());
					} else {
						if (FileMode.GITLINK.equals(dcEntry.getFileMode())) {
							// Do not check the content of submodule entries
							// Use the old entry information instead.
							dcEntry.copyMetaData(index.getEntry(dcEntry
									.getPathString()));
						} else {
							// insert object
							if (inserter == null)
								inserter = repo.newObjectInserter();

							InputStream inputStream = fTree.openEntryStream();
							try {
								dcEntry.setObjectId(inserter.insert(
										Constants.OBJ_BLOB, entryLength,
										inputStream));
							} finally {
								inputStream.close();
							}
						}
					}

					// update index
					dcEditor.add(new PathEdit(path) {
						@Override
						public void apply(DirCacheEntry ent) {
							ent.copyMetaData(dcEntry);
						}
					});
					// add to temporary in-core index
					dcBuilder.add(dcEntry);

					if (emptyCommit
							&& (hTree == null || !hTree.idEqual(fTree) || hTree
									.getEntryRawMode() != fTree
									.getEntryRawMode()))
						// this is a change
						emptyCommit = false;
				} else {
					// if no file exists on disk, remove entry from index and
					// don't add it to temporary in-core index
					dcEditor.add(new DeletePath(path));

					if (emptyCommit && hTree != null)
						// this is a change
						emptyCommit = false;
				}

				// keep track of processed path
				onlyProcessed[pos] = true;
			} else {
				// add entries from HEAD for all other paths
				if (hTree != null) {
					// create a new DirCacheEntry with data retrieved from HEAD
					final DirCacheEntry dcEntry = new DirCacheEntry(path);
					dcEntry.setObjectId(hTree.getEntryObjectId());
					dcEntry.setFileMode(hTree.getEntryFileMode());

					// add to temporary in-core index
					dcBuilder.add(dcEntry);
				}
			}
		}

		// there must be no unprocessed paths left at this point; otherwise an
		// untracked or unknown path has been specified
		for (int i = 0; i < onlyProcessed.length; i++)
			if (!onlyProcessed[i])
				throw new JGitInternalException(MessageFormat.format(
						JGitText.get().entryNotFoundByPath, only.get(i)));

		// there must be at least one change
		if (emptyCommit)
			throw new JGitInternalException(JGitText.get().emptyCommit);

		// update index
		dcEditor.commit();
		// finish temporary in-core index used for this commit
		dcBuilder.finish();
		return inCoreIndex;
	}

	/**
	 * Look an entry's path up in the list of paths specified by the --only/ -o
	 * option
	 *
	 * In case the complete (file) path (e.g. "d1/d2/f1") cannot be found in
	 * <code>only</code>, lookup is also tried with (parent) directory paths
	 * (e.g. "d1/d2" and "d1").
	 *
	 * @param pathString
	 *            entry's path
	 * @return the item's index in <code>only</code>; -1 if no item matches
	 */
	private int lookupOnly(String pathString) {
		int i = 0;
		for (String o : only) {
			String p = pathString;
			while (true) {
				if (p.equals(o))
					return i;
				int l = p.lastIndexOf("/");
				if (l < 1)
					break;
				p = p.substring(0, l);
			}
			i++;
		}
		return -1;
	}

	/**
	 * Sets default values for not explicitly specified options. Then validates
	 * that all required data has been provided.
	 *
	 * @param state
	 *            the state of the repository we are working on
	 *
	 * @throws NoMessageException
	 *             if the commit message has not been specified
	 */
	private void processOptions(RepositoryState state) throws NoMessageException {
		if (committer == null)
			committer = new PersonIdent(repo);
		if (author == null)
			author = committer;

		// when doing a merge commit parse MERGE_HEAD and MERGE_MSG files
		if (state == RepositoryState.MERGING_RESOLVED) {
			try {
				parents = repo.readMergeHeads();
			} catch (IOException e) {
				throw new JGitInternalException(MessageFormat.format(
						JGitText.get().exceptionOccurredDuringReadingOfGIT_DIR,
						Constants.MERGE_HEAD, e), e);
			}
			if (message == null) {
				try {
					message = repo.readMergeCommitMsg();
				} catch (IOException e) {
					throw new JGitInternalException(MessageFormat.format(
							JGitText.get().exceptionOccurredDuringReadingOfGIT_DIR,
							Constants.MERGE_MSG, e), e);
				}
			}
		}
		if (message == null)
			// as long as we don't suppport -C option we have to have
			// an explicit message
			throw new NoMessageException(JGitText.get().commitMessageNotSpecified);
	}

	/**
	 * @param message
	 *            the commit message used for the {@code commit}
	 * @return {@code this}
	 */
	public CommitCommand setMessage(String message) {
		checkCallable();
		this.message = message;
		return this;
	}

	/**
	 * @return the commit message used for the <code>commit</code>
	 */
	public String getMessage() {
		return message;
	}

	/**
	 * Sets the committer for this {@code commit}. If no committer is explicitly
	 * specified because this method is never called or called with {@code null}
	 * value then the committer will be deduced from config info in repository,
	 * with current time.
	 *
	 * @param committer
	 *            the committer used for the {@code commit}
	 * @return {@code this}
	 */
	public CommitCommand setCommitter(PersonIdent committer) {
		checkCallable();
		this.committer = committer;
		return this;
	}

	/**
	 * Sets the committer for this {@code commit}. If no committer is explicitly
	 * specified because this method is never called or called with {@code null}
	 * value then the committer will be deduced from config info in repository,
	 * with current time.
	 *
	 * @param name
	 *            the name of the committer used for the {@code commit}
	 * @param email
	 *            the email of the committer used for the {@code commit}
	 * @return {@code this}
	 */
	public CommitCommand setCommitter(String name, String email) {
		checkCallable();
		return setCommitter(new PersonIdent(name, email));
	}

	/**
	 * @return the committer used for the {@code commit}. If no committer was
	 *         specified {@code null} is returned and the default
	 *         {@link PersonIdent} of this repo is used during execution of the
	 *         command
	 */
	public PersonIdent getCommitter() {
		return committer;
	}

	/**
	 * Sets the author for this {@code commit}. If no author is explicitly
	 * specified because this method is never called or called with {@code null}
	 * value then the author will be set to the committer.
	 *
	 * @param author
	 *            the author used for the {@code commit}
	 * @return {@code this}
	 */
	public CommitCommand setAuthor(PersonIdent author) {
		checkCallable();
		this.author = author;
		return this;
	}

	/**
	 * Sets the author for this {@code commit}. If no author is explicitly
	 * specified because this method is never called or called with {@code null}
	 * value then the author will be set to the committer.
	 *
	 * @param name
	 *            the name of the author used for the {@code commit}
	 * @param email
	 *            the email of the author used for the {@code commit}
	 * @return {@code this}
	 */
	public CommitCommand setAuthor(String name, String email) {
		checkCallable();
		return setAuthor(new PersonIdent(name, email));
	}

	/**
	 * @return the author used for the {@code commit}. If no author was
	 *         specified {@code null} is returned and the default
	 *         {@link PersonIdent} of this repo is used during execution of the
	 *         command
	 */
	public PersonIdent getAuthor() {
		return author;
	}

	/**
	 * If set to true the Commit command automatically stages files that have
	 * been modified and deleted, but new files not known by the repository are
	 * not affected. This corresponds to the parameter -a on the command line.
	 *
	 * @param all
	 * @return {@code this}
	 * @throws JGitInternalException
	 *             in case of an illegal combination of arguments/ options
	 */
	public CommitCommand setAll(boolean all) {
		checkCallable();
		if (!only.isEmpty())
			throw new JGitInternalException(MessageFormat.format(
					JGitText.get().illegalCombinationOfArguments, "--all",
					"--only"));
		this.all = all;
		return this;
	}

	/**
	 * Used to amend the tip of the current branch. If set to true, the previous
	 * commit will be amended. This is equivalent to --amend on the command
	 * line.
	 *
	 * @param amend
	 * @return {@code this}
	 */
	public CommitCommand setAmend(boolean amend) {
		checkCallable();
		this.amend = amend;
		return this;
	}

	/**
	 * Commit dedicated path only
	 *
	 * This method can be called several times to add multiple paths. Full file
	 * paths are supported as well as directory paths; in the latter case this
	 * commits all files/ directories below the specified path.
	 *
	 * @param only
	 *            path to commit
	 * @return {@code this}
	 */
	public CommitCommand setOnly(String only) {
		checkCallable();
		if (all)
			throw new JGitInternalException(MessageFormat.format(
					JGitText.get().illegalCombinationOfArguments, "--only",
					"--all"));
		String o = only.endsWith("/") ? only.substring(0, only.length() - 1)
				: only;
		// ignore duplicates
		if (!this.only.contains(o))
			this.only.add(o);
		return this;
	}

	/**
	 * If set to true a change id will be inserted into the commit message
	 *
	 * An existing change id is not replaced. An initial change id (I000...)
	 * will be replaced by the change id.
	 *
	 * @param insertChangeId
	 *
	 * @return {@code this}
	 */
	public CommitCommand setInsertChangeId(boolean insertChangeId) {
		checkCallable();
		this.insertChangeId = insertChangeId;
		return this;
	}

	/**
	 * Override the message written to the reflog
	 *
	 * @param reflogComment
	 * @return {@code this}
	 */
	public CommitCommand setReflogComment(String reflogComment) {
		this.reflogComment = reflogComment;
		return this;
	}

}