/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 */

#include "nsIRequestObserver.idl"

interface nsIRequest;
interface nsIInputStream;
interface nsIOutputStream;
interface nsIEventQueue;

/**
 * The nsIChannel::AsyncRead notification handler.  It accepts
 * data from the channel, when the channel is ready to provide it.
 */
[scriptable, uuid(1a637020-1482-11d3-9333-00104ba0fd40)]
interface nsIStreamListener : nsIRequestObserver
{
    /**
     * Called when there is data to be read from the channel.
     *
     * @param request - the request returned by AsyncRead
     * @param ctxt - opaque parameter passed to AsyncRead
     * @param input - temporary input stream for reading data chunk
     * @param offset - current stream position (informational)
     * @param count - number of bytes that can be read without blocking
     *
     * @return NS_OK - if successfully read something.
     * @return NS_BASE_STREAM_CLOSED - if done reading data. NOTE: this is
     *   NOT equivalent to reading zero bytes and returning NS_OK.
     * @return NS_BASE_STREAM_WOULD_BLOCK - if no data can be read at
     *   this time.  This implicitly calls Suspend on the channel.  Call
     *   Resume on the channel to continue the AsyncRead when more data
     *   becomes available.
     * @return <other-error> - if failure.
     */
    void onDataAvailable(in nsIRequest request,
                         in nsISupports ctxt, 
                         in nsIInputStream input,
                         in unsigned long offset,
                         in unsigned long count);
};

/**
 * A stream listener proxy is used to ship data over to another thread specified
 * by the thread's event queue.  The "true" stream listener's methods are
 * invoked on the other thread.
 *
 * This interface only provides the initialization needed after construction. 
 * Otherwise, these objects may be used as a nsIStreamListener.
 */
[scriptable, uuid(e400e688-6b54-4a84-8c4e-56b40281981a)]
interface nsIStreamListenerProxy : nsIStreamListener
{
    /**
     * Initializes an nsIStreamListenerProxy.
     *
     * @param listener - receives listener notifications on the other thread
     * @param eventQ - may be NULL indicating the calling thread's event queue
     * @param bufferSegmentSize - passing zero indicates the default
     * @param bufferMaxSize - passing zero indicates the default
     */
    void init(in nsIStreamListener listener,
              in nsIEventQueue eventQ,
              in unsigned long bufferSegmentSize,
              in unsigned long bufferMaxSize);
};

/**
 * A simple stream listener can be used with AsyncRead to supply data to
 * a output stream.
 */
[scriptable, uuid(a9b84f6a-0824-4278-bae6-bfca0570a26e)]
interface nsISimpleStreamListener : nsIStreamListener
{
    /**
     * Initialize the simple stream listener.
     *
     * @param sink - data will be read from the channel to this output stream
     * @param observer - optional stream observer (can be NULL)
     */
    void init(in nsIOutputStream sink,
              in nsIRequestObserver observer);
};

/**
 * An asynchronous stream listener is used to ship data over to another thread specified
 * by the thread's event queue. The receiver stream listener is then used to receive
 * the notifications on the other thread. 
 *
 * This interface only provides the initialization needed after construction. Otherwise,
 * these objects are used simply as nsIStreamListener.
 */
[scriptable, uuid(1b012ade-91bf-11d3-8cd9-0060b0fc14a3)]
interface nsIAsyncStreamListener : nsIStreamListener
{
    /**
     * Initializes an nsIAsyncStreamListener. 
     * @param eventQueue - may be null indicating the calling thread's event queue
     */
    void init(in nsIStreamListener receiver,
              in nsIEventQueue eventQueue);
};

/**
 * As data "flows" into a stream listener tee, it is copied to the output stream
 * and then forwarded onto the real listener.
 */
[scriptable, uuid(fb683e76-d42b-41a4-8ae6-65a6c2b146e5)]
interface nsIStreamListenerTee : nsIStreamListener
{
    void init(in nsIStreamListener listener,
              in nsIOutputStream sink);
};
