/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the License).  You may not use this file except in
 * compliance with the License.
 *
 * You can obtain a copy of the license at
 * https://glassfish.dev.java.net/public/CDDLv1.0.html or
 * glassfish/bootstrap/legal/CDDLv1.0.txt.
 * See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL
 * Header Notice in each file and include the License file
 * at glassfish/bootstrap/legal/CDDLv1.0.txt.
 * If applicable, add the following below the CDDL Header,
 * with the fields enclosed by brackets [] replaced by
 * you own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 *
 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
 */

package com.sun.grizzly;

import java.nio.ByteBuffer;

/**
 * An interface that knows how to parse bytes into a protocol data unit.
 *
 * @author Charlie Hunt
 */
public interface ProtocolParser<T> {
    
    /**
     * Is this ProtocolParser expecting more data ?
     * 
     * This method is typically called after a call to <code>parseBytes()</code>
     * to determine if the <code>ByteBuffer</code> which has been parsed
     * contains a partial message
     * 
     * @return - <code>true</code> if more bytes are needed to construct a
     *           message;  <code>false</code>, if no 
     *           additional bytes remain to be parsed into a <code>T</code>.
     *	 	 Note that if no partial message exists, this method should
     *		 return false.
     */
    public boolean isExpectingMoreData();
    
    /**
     * Are there more bytes to be parsed in the <code>ByteBuffer</code> given
     * to this ProtocolParser's <code>setBuffer</code> ?
     * 
     * This method is typically called after a call to <code>parseBytes()</code>
     * to determine if the <code>ByteBuffer</code> has more bytes which need to
     * parsed into a message.
     * 
     * @return <code>true</code> if there are more bytes to be parsed.
     *         Otherwise <code>false</code>.
     */
    public boolean hasMoreBytesToParse();

    
    /**
     * Get the next complete message from the buffer, which can then be
     * processed by the next filter in the protocol chain. Because not all
     * filters will understand protocol messages, this method should also
     * set the position and limit of the buffer at the start and end
     * boundaries of the message. Filters in the protocol chain can
     * retrieve this message via context.getAttribute(MESSAGE)
     *
     * @return The next message in the buffer. If there isn't such a message,
     *	return <code>null.</code>
     *
     */
    public T getNextMessage();

    /**
     * Indicates whether the buffer has a complete message that can be
     * returned from <code>getNextMessage</code>. Smart implementations of
     * this will set up all the information so that an actual call to
     * <code>getNextMessage</code> doesn't need to re-parse the data.
     */
    public boolean hasNextMessage();

    /**
     * Set the buffer to be parsed. This method should store the buffer and
     * its state so that subsequent calls to <code>getNextMessage</code>
     * will return distinct messages, and the buffer can be restored after
     * parsing when the <code>releaseBuffer</code> method is called.
     */
    public void startBuffer(ByteBuffer bb);
    
    /**
     * No more parsing will be done on the buffer passed to
     * <code>startBuffer.</code>
     * Set up the buffer so that its position is the first byte that was
     * not part of a full message, and its limit is the original limit of
     * the buffer.
     *
     * @return -- true if the parser has saved some state (e.g. information
     * data in the buffer that hasn't been returned in a full message);
     * otherwise false. If this method returns true, the framework will
     * make sure that the same parser is used to process the buffer after
     * more data has been read.
     */
    public boolean releaseBuffer();

    /**
     * Used to associate a particular parser with a connection
     */
    public static String PARSER = "ProtocolParser";

    /**
     * Holds the message returned from <code>getNextMessage</code> for
     * use by downstream filters
     */
    public static String MESSAGE = "ProtocolMessage";
}