/*
 * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.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.transport;

import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.errors.NotSupportedException;
import org.eclipse.jgit.errors.TransportException;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevObject;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.transport.RemoteRefUpdate.Status;

/**
 * Class performing push operation on remote repository.
 *
 * @see Transport#push(ProgressMonitor, Collection)
 */
class PushProcess {
	/** Task name for {@link ProgressMonitor} used during opening connection. */
	static final String PROGRESS_OPENING_CONNECTION = "Opening connection";

	/** Transport used to perform this operation. */
	private final Transport transport;

	/** Push operation connection created to perform this operation */
	private PushConnection connection;

	/** Refs to update on remote side. */
	private final Map<String, RemoteRefUpdate> toPush;

	/** Revision walker for checking some updates properties. */
	private final RevWalk walker;

	/**
	 * Create process for specified transport and refs updates specification.
	 *
	 * @param transport
	 *            transport between remote and local repository, used to create
	 *            connection.
	 * @param toPush
	 *            specification of refs updates (and local tracking branches).
	 * @throws TransportException
	 */
	PushProcess(final Transport transport,
			final Collection<RemoteRefUpdate> toPush) throws TransportException {
		this.walker = new RevWalk(transport.local);
		this.transport = transport;
		this.toPush = new HashMap<String, RemoteRefUpdate>();
		for (final RemoteRefUpdate rru : toPush) {
			if (this.toPush.put(rru.getRemoteName(), rru) != null)
				throw new TransportException(
						"Duplicate remote ref update is illegal. Affected remote name: "
								+ rru.getRemoteName());
		}
	}

	/**
	 * Perform push operation between local and remote repository - set remote
	 * refs appropriately, send needed objects and update local tracking refs.
	 * <p>
	 * When {@link Transport#isDryRun()} is true, result of this operation is
	 * just estimation of real operation result, no real action is performed.
	 *
	 * @param monitor
	 *            progress monitor used for feedback about operation.
	 * @return result of push operation with complete status description.
	 * @throws NotSupportedException
	 *             when push operation is not supported by provided transport.
	 * @throws TransportException
	 *             when some error occurred during operation, like I/O, protocol
	 *             error, or local database consistency error.
	 */
	PushResult execute(final ProgressMonitor monitor)
			throws NotSupportedException, TransportException {
		monitor.beginTask(PROGRESS_OPENING_CONNECTION, ProgressMonitor.UNKNOWN);

		final PushResult res = new PushResult();
		connection = transport.openPush();
		try {
			res.setAdvertisedRefs(transport.getURI(), connection.getRefsMap());
			res.setRemoteUpdates(toPush);
			monitor.endTask();

			final Map<String, RemoteRefUpdate> preprocessed = prepareRemoteUpdates();
			if (transport.isDryRun())
				modifyUpdatesForDryRun();
			else if (!preprocessed.isEmpty())
				connection.push(monitor, preprocessed);
		} finally {
			connection.close();
			res.addMessages(connection.getMessages());
		}
		if (!transport.isDryRun())
			updateTrackingRefs();
		for (final RemoteRefUpdate rru : toPush.values()) {
			final TrackingRefUpdate tru = rru.getTrackingRefUpdate();
			if (tru != null)
				res.add(tru);
		}
		return res;
	}

	private Map<String, RemoteRefUpdate> prepareRemoteUpdates()
			throws TransportException {
		final Map<String, RemoteRefUpdate> result = new HashMap<String, RemoteRefUpdate>();
		for (final RemoteRefUpdate rru : toPush.values()) {
			final Ref advertisedRef = connection.getRef(rru.getRemoteName());
			final ObjectId advertisedOld = (advertisedRef == null ? ObjectId
					.zeroId() : advertisedRef.getObjectId());

			if (rru.getNewObjectId().equals(advertisedOld)) {
				if (rru.isDelete()) {
					// ref does exist neither locally nor remotely
					rru.setStatus(Status.NON_EXISTING);
				} else {
					// same object - nothing to do
					rru.setStatus(Status.UP_TO_DATE);
				}
				continue;
			}

			// caller has explicitly specified expected old object id, while it
			// has been changed in the mean time - reject
			if (rru.isExpectingOldObjectId()
					&& !rru.getExpectedOldObjectId().equals(advertisedOld)) {
				rru.setStatus(Status.REJECTED_REMOTE_CHANGED);
				continue;
			}

			// create ref (hasn't existed on remote side) and delete ref
			// are always fast-forward commands, feasible at this level
			if (advertisedOld.equals(ObjectId.zeroId()) || rru.isDelete()) {
				rru.setFastForward(true);
				result.put(rru.getRemoteName(), rru);
				continue;
			}

			// check for fast-forward:
			// - both old and new ref must point to commits, AND
			// - both of them must be known for us, exist in repository, AND
			// - old commit must be ancestor of new commit
			boolean fastForward = true;
			try {
				RevObject oldRev = walker.parseAny(advertisedOld);
				final RevObject newRev = walker.parseAny(rru.getNewObjectId());
				if (!(oldRev instanceof RevCommit)
						|| !(newRev instanceof RevCommit)
						|| !walker.isMergedInto((RevCommit) oldRev,
								(RevCommit) newRev))
					fastForward = false;
			} catch (MissingObjectException x) {
				fastForward = false;
			} catch (Exception x) {
				throw new TransportException(transport.getURI(),
						"reading objects from local repository failed: "
								+ x.getMessage(), x);
			}
			rru.setFastForward(fastForward);
			if (!fastForward && !rru.isForceUpdate())
				rru.setStatus(Status.REJECTED_NONFASTFORWARD);
			else
				result.put(rru.getRemoteName(), rru);
		}
		return result;
	}

	private void modifyUpdatesForDryRun() {
		for (final RemoteRefUpdate rru : toPush.values())
			if (rru.getStatus() == Status.NOT_ATTEMPTED)
				rru.setStatus(Status.OK);
	}

	private void updateTrackingRefs() {
		for (final RemoteRefUpdate rru : toPush.values()) {
			final Status status = rru.getStatus();
			if (rru.hasTrackingRefUpdate()
					&& (status == Status.UP_TO_DATE || status == Status.OK)) {
				// update local tracking branch only when there is a chance that
				// it has changed; this is possible for:
				// -updated (OK) status,
				// -up to date (UP_TO_DATE) status
				try {
					rru.updateTrackingRef(walker);
				} catch (IOException e) {
					// ignore as RefUpdate has stored I/O error status
				}
			}
		}
	}
}