//
//  ========================================================================
//  Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.spdy.api;

import java.util.EventListener;

import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

/**
 * <p>A {@link SessionFrameListener} is the passive counterpart of a {@link Session} and receives events happening
 * on a SPDY session.</p>
 *
 * @see Session
 */
public interface SessionFrameListener extends EventListener
{
    /**
     * <p>Callback invoked when a request to create a stream has been received.</p>
     * <p>Application code should implement this method and reply to the stream creation, eventually
     * sending data:</p>
     * <pre>
     * public StreamFrameListener onSyn(Stream stream, SynInfo synInfo)
     * {
     *     // Do something with the metadata contained in synInfo
     *
     *     if (stream.isHalfClosed()) // The other peer will not send data
     *     {
     *         stream.reply(new ReplyInfo(false));
     *         stream.data(new StringDataInfo("foo", true));
     *         return null; // Not interested in further stream events
     *     }
     *
     *     ...
     * }
     * </pre>
     * <p>Alternatively, if the stream creation requires reading data sent from the other peer:</p>
     * <pre>
     * public StreamFrameListener onSyn(Stream stream, SynInfo synInfo)
     * {
     *     // Do something with the metadata contained in synInfo
     *
     *     if (!stream.isHalfClosed()) // The other peer will send data
     *     {
     *         stream.reply(new ReplyInfo(true));
     *         return new Stream.FrameListener.Adapter() // Interested in stream events
     *         {
     *             public void onData(Stream stream, DataInfo dataInfo)
     *             {
     *                 // Do something with the incoming data in dataInfo
     *             }
     *         };
     *     }
     *
     *     ...
     * }
     * </pre>
     *
     * @param stream  the stream just created
     * @param synInfo the metadata sent on stream creation
     * @return a listener for stream events, or null if there is no interest in being notified of stream events
     */
    public StreamFrameListener onSyn(Stream stream, SynInfo synInfo);

    /**
     * <p>Callback invoked when a stream error happens.</p>
     *
     * @param session the session
     * @param rstInfo the metadata of the stream error
     */
    public void onRst(Session session, RstInfo rstInfo);

    /**
     * <p>Callback invoked when a request to configure the SPDY connection has been received.</p>
     *
     * @param session the session
     * @param settingsInfo the metadata sent to configure
     */
    public void onSettings(Session session, SettingsInfo settingsInfo);

    /**
     * <p>Callback invoked when a ping request has completed its round-trip.</p>
     *
     * @param session the session
     * @param pingResultInfo the metadata received
     */
    public void onPing(Session session, PingResultInfo pingResultInfo);

    /**
     * <p>Callback invoked when the other peer signals that it is closing the connection.</p>
     *
     * @param session the session
     * @param goAwayResultInfo the metadata sent
     */
    public void onGoAway(Session session, GoAwayResultInfo goAwayResultInfo);

    /**
     * <p>Callback invoked when an exception is thrown during the processing of an event on a
     * SPDY session.</p>
     * <p>Examples of such conditions are invalid frames received, corrupted headers compression state, etc.</p>
     *
     * @param session the session
     * @param x the exception that caused the event processing failure
     */
    public void onFailure(Session session, Throwable x);


    /**
     * <p>Empty implementation of {@link SessionFrameListener}</p>
     */
    public static class Adapter implements SessionFrameListener
    {
        private static final Logger logger = Log.getLogger(Adapter.class);

        @Override
        public StreamFrameListener onSyn(Stream stream, SynInfo synInfo)
        {
            return null;
        }

        @Override
        public void onRst(Session session, RstInfo rstInfo)
        {
        }

        @Override
        public void onSettings(Session session, SettingsInfo settingsInfo)
        {
        }

        @Override
        public void onPing(Session session, PingResultInfo pingResultInfo)
        {
        }

        @Override
        public void onGoAway(Session session, GoAwayResultInfo goAwayResultInfo)
        {
        }

        @Override
        public void onFailure(Session session, Throwable x)
        {
            logger.info("", x);
        }
    }
}
