/* -*- 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 "nsIStreamObserver.idl"

interface nsIChannel;
interface nsIInputStream;
interface nsIOutputStream;
interface nsIEventQueue;

/**
 * The nsIChannel::AsyncWrite notification handler.  It provides
 * data to the channel, when the channel is ready to accept it.
 */
[scriptable, uuid(d10ef7a9-b728-43d4-9c49-74172186d691)]
interface nsIStreamProvider : nsIStreamObserver
{
    /**
     * Called when data may be written to the channel.
     *
     * @param request - the request returned by AsyncWrite
     * @param ctxt - opaque parameter passed to AsyncWrite
     * @param output - output stream for writing data chunk
     * @param offset - current stream position (informational)
     * @param count - number of bytes that can be written without blocking
     *
     * @return NS_OK - if successfully wrote something.
     * @return NS_BASE_STREAM_CLOSED - if done writing data. NOTE: this is
     *   NOT equivalent to writing zero bytes and returning NS_OK.
     * @return NS_BASE_STREAM_WOULD_BLOCK - if no data can be written at
     *   this time.  This implicitly calls Suspend on the channel.  Call
     *   Resume on the channel to continue the AsyncWrite when more data
     *   becomes available.
     * @return <other-error> - if failure.
     */
    void onDataWritable(in nsIRequest request,
                        in nsISupports ctxt,
                        in nsIOutputStream output,
                        in unsigned long offset,
                        in unsigned long count);
};

/**
 * A stream provider proxy is used to ship data over to another thread specified
 * by the thread's event queue.  The "true" stream provider'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 nsIStreamProvider.
 */
[scriptable, uuid(5c3b0bac-605a-49ac-880e-5c8b993f7d2b)]
interface nsIStreamProviderProxy : nsIStreamProvider
{
    /**
     * Initializes an nsIStreamProviderProxy.
     *
     * @param provider - receives provider notifications on the other thread.
     * @param eventQ - may be NULL indicating the calling thread's event queue.
     */
    void init(in nsIStreamProvider provider,
              in nsIEventQueue eventQ,
              in unsigned long bufferSegmentSize,
              in unsigned long bufferMaxSize);
};

/**
 * A simple stream provider can be used with AsyncWrite to supply data from 
 * an existing input stream.
 */
[scriptable, uuid(c20bb3b9-0755-4eff-9222-3537f9e89082)]
interface nsISimpleStreamProvider : nsIStreamProvider
{
    /**
     * Initialize the simple stream provider.
     *
     * @param - data will be read from this input stream to the channel
     * @param - optional stream observer (can be NULL)
     */
    void init(in nsIInputStream source,
              in nsIStreamObserver observer);
};