/*

 * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.net.http.websocket;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.util.concurrent.CompletableFuture;

import java.util.function.BiConsumer;

import java.util.function.Supplier;

/*

 * A WebSocket view of the underlying communication channel. This view provides

 * an asynchronous exchange of WebSocket messages rather than asynchronous

 * exchange of bytes.

 *

 * Methods sendText, sendBinary, sendPing, sendPong and sendClose initiate a

 * corresponding operation and return a CompletableFuture (CF) which will

 * complete once the operation has completed (succeeded or failed).

 *

 * These methods are designed such that their clients may take an advantage on

 * possible implementation optimizations. Namely, these methods:

 *

 * 1. May return null which is considered the same as a CF completed normally

 * 2. Accept an arbitrary attachment to complete a CF with

 * 3. Accept an action to take once the operation has completed

 *

 * All of the above allows not to create unnecessary instances of CF.

 * For example, if a message has been sent straight away, there's no need to

 * create a CF (given the parties agree on the meaning of null and are prepared

 * to handle it).

 * If the result of a returned CF is useless to the client, they may specify the

 * exact instance (attachment) they want the CF to complete with. Thus, no need

 * to create transforming stages (e.g. thenApply(useless -> myResult)).

 * If there is the same action that needs to be done each time the CF completes,

 * the client may pass it directly to the method instead of creating a dependant

 * stage (e.g. whenComplete(action)).

 */

public interface Transport {

    <T> CompletableFuture<T> sendText(CharSequence message,

                                      boolean isLast,

                                      T attachment,

                                      BiConsumer<? super T, ? super Throwable> action);

    <T> CompletableFuture<T> sendBinary(ByteBuffer message,

                                        boolean isLast,

                                        T attachment,

                                        BiConsumer<? super T, ? super Throwable> action);

    <T> CompletableFuture<T> sendPing(ByteBuffer message,

                                      T attachment,

                                      BiConsumer<? super T, ? super Throwable> action);

    <T> CompletableFuture<T> sendPong(ByteBuffer message,

                                      T attachment,

                                      BiConsumer<? super T, ? super Throwable> action);

    /*

     * Sends a Pong message with initially unknown data. Used for sending the

     * most recent automatic Pong reply.

     */

    <T> CompletableFuture<T> sendPong(Supplier<? extends ByteBuffer> message,

                                      T attachment,

                                      BiConsumer<? super T, ? super Throwable> action);

    <T> CompletableFuture<T> sendClose(int statusCode,

                                       String reason,

                                       T attachment,

                                       BiConsumer<? super T, ? super Throwable> action);

    void request(long n);

    /*

     * Why is this method needed? Since receiving of messages operates through

     * callbacks this method allows to abstract out what constitutes as a

     * message being received (i.e. to decide outside this type when exactly one

     * should decrement the demand).

     */

    void acknowledgeReception(); // TODO: hide

    /*

     * If this method is invoked, then all pending and subsequent send

     * operations will fail with IOException.

     */

    void closeOutput() throws IOException;

    void closeInput() throws IOException;

}