/*
 * Copyright (C) 2011, Google Inc.
 * 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.util.Collection;

import org.eclipse.jgit.lib.ObjectId;

/**
 * Hook invoked by {@link UploadPack} before during critical phases.
 * <p>
 * If any hook function throws {@link ServiceMayNotContinueException} then
 * processing stops immediately and the exception is thrown up the call stack.
 * Most phases of UploadPack will try to report the exception's message text to
 * the end-user over the client's protocol connection.
 */
public interface PreUploadHook {
	/** A simple no-op hook. */
	public static final PreUploadHook NULL = new PreUploadHook() {
		public void onBeginNegotiateRound(UploadPack up,
				Collection<? extends ObjectId> wants, int cntOffered)
				throws ServiceMayNotContinueException {
			// Do nothing.
		}

		public void onEndNegotiateRound(UploadPack up,
				Collection<? extends ObjectId> wants, int cntCommon,
				int cntNotFound, boolean ready)
				throws ServiceMayNotContinueException {
			// Do nothing.
		}

		public void onSendPack(UploadPack up,
				Collection<? extends ObjectId> wants,
				Collection<? extends ObjectId> haves)
				throws ServiceMayNotContinueException {
			// Do nothing.
		}
	};

	/**
	 * Invoked before negotiation round is started.
	 *
	 * @param up
	 *            the upload pack instance handling the connection.
	 * @param wants
	 *            the list of wanted objects.
	 * @param cntOffered
	 *            number of objects the client has offered.
	 * @throws ServiceMayNotContinueException
	 *             abort; the message will be sent to the user.
	 */
	public void onBeginNegotiateRound(UploadPack up,
			Collection<? extends ObjectId> wants, int cntOffered)
			throws ServiceMayNotContinueException;

	/**
	 * Invoked after a negotiation round is completed.
	 *
	 * @param up
	 *            the upload pack instance handling the connection.
	 * @param wants
	 *            the list of wanted objects.
	 * @param cntCommon
	 *            number of objects this round found to be common. In a smart
	 *            HTTP transaction this includes the objects that were
	 *            previously found to be common.
	 * @param cntNotFound
	 *            number of objects in this round the local repository does not
	 *            have, but that were offered as potential common bases.
	 * @param ready
	 *            true if a pack is ready to be sent (the commit graph was
	 *            successfully cut).
	 * @throws ServiceMayNotContinueException
	 *             abort; the message will be sent to the user.
	 */
	public void onEndNegotiateRound(UploadPack up,
			Collection<? extends ObjectId> wants, int cntCommon,
			int cntNotFound, boolean ready)
			throws ServiceMayNotContinueException;

	/**
	 * Invoked just before a pack will be sent to the client.
	 *
	 * @param up
	 *            the upload pack instance handling the connection.
	 * @param wants
	 *            the list of wanted objects. These may be RevObject or
	 *            RevCommit if the processed parsed them. Implementors should
	 *            not rely on the values being parsed.
	 * @param haves
	 *            the list of common objects. Empty on an initial clone request.
	 *            These may be RevObject or RevCommit if the processed parsed
	 *            them. Implementors should not rely on the values being parsed.
	 * @throws ServiceMayNotContinueException
	 *             abort; the message will be sent to the user.
	 */
	public void onSendPack(UploadPack up, Collection<? extends ObjectId> wants,
			Collection<? extends ObjectId> haves)
			throws ServiceMayNotContinueException;
}
