/*
    * 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.io.OutputStream;
  import java.text.MessageFormat;
  import java.util.Collection;
  import java.util.Collections;
  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.internal.JGitText;
  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, OutputStream)
   */
  class PushProcess {
  	/** Task name for {@link ProgressMonitor} used during opening connection. */
  	static final String PROGRESS_OPENING_CONNECTION = JGitText.get().openingConnection;
  
  	/** 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;
  
  	/** an outputstream to write messages to */
  	private final OutputStream out;
  
  	/**
  	 * 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(transport, toPush, null);
 	}
 
 	/**
 	 * 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).
 	 * @param out
 	 *            OutputStream to write messages to
 	 * @throws TransportException
 	 */
 	PushProcess(final Transport transport,
 			final Collection<RemoteRefUpdate> toPush, OutputStream out)
 			throws TransportException {
 		this.walker = new RevWalk(transport.local);
 		this.transport = transport;
 		this.toPush = new HashMap<String, RemoteRefUpdate>();
 		this.out = out;
 		for (final RemoteRefUpdate rru : toPush) {
 			if (this.toPush.put(rru.getRemoteName(), rru) != null)
 				throw new TransportException(MessageFormat.format(
 						JGitText.get().duplicateRemoteRefUpdateIsIllegal, 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 {
 		try {
 			monitor.beginTask(PROGRESS_OPENING_CONNECTION,
 					ProgressMonitor.UNKNOWN);
 
 			final PushResult res = new PushResult();
 			connection = transport.openPush();
 			try {
 				res.setAdvertisedRefs(transport.getURI(), connection
 						.getRefsMap());
 				res.peerUserAgent = connection.getPeerUserAgent();
 				res.setRemoteUpdates(toPush);
 				monitor.endTask();
 
 				final Map<String, RemoteRefUpdate> preprocessed = prepareRemoteUpdates();
 				if (transport.isDryRun())
 					modifyUpdatesForDryRun();
 				else if (!preprocessed.isEmpty())
 					connection.push(monitor, preprocessed, out);
 			} 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;
 		} finally {
 			walker.close();
 		}
 	}
 
 	private Map<String, RemoteRefUpdate> prepareRemoteUpdates()
 			throws TransportException {
 		boolean atomic = transport.isPushAtomic();
 		final Map<String, RemoteRefUpdate> result = new HashMap<String, RemoteRefUpdate>();
 		for (final RemoteRefUpdate rru : toPush.values()) {
 			final Ref advertisedRef = connection.getRef(rru.getRemoteName());
 			ObjectId advertisedOld = null;
 			if (advertisedRef != null) {
 				advertisedOld = advertisedRef.getObjectId();
 			}
 			if (advertisedOld == null) {
 				advertisedOld = ObjectId.zeroId();
 			}
 
 			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);
 				if (atomic) {
 					return rejectAll();
 				}
 				continue;
 			}
 			if (!rru.isExpectingOldObjectId()) {
 				rru.setExpectedOldObjectId(advertisedOld);
 			}
 
 			// 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(), MessageFormat.format(
 						JGitText.get().readingObjectsFromLocalRepositoryFailed, x.getMessage()), x);
 			}
 			rru.setFastForward(fastForward);
 			if (!fastForward && !rru.isForceUpdate()) {
 				rru.setStatus(Status.REJECTED_NONFASTFORWARD);
 				if (atomic) {
 					return rejectAll();
 				}
 			} else {
 				result.put(rru.getRemoteName(), rru);
 			}
 		}
 		return result;
 	}
 
 	private Map<String, RemoteRefUpdate> rejectAll() {
 		for (RemoteRefUpdate rru : toPush.values()) {
 			if (rru.getStatus() == Status.NOT_ATTEMPTED) {
 				rru.setStatus(RemoteRefUpdate.Status.REJECTED_OTHER_REASON);
 				rru.setMessage(JGitText.get().transactionAborted);
 			}
 		}
 		return Collections.emptyMap();
 	}
 
 	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
 				}
 			}
 		}
 	}
 }