/*

 * Copyright (c) 2015, 2016, 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

 */

package java.net.http;

import java.io.IOException;

import java.util.concurrent.CompletableFuture;

import static java.net.http.HttpClient.Version.HTTP_1_1;

/**

 * Splits request so that headers and body can be sent separately with optional

 * (multiple) responses in between (e.g. 100 Continue). Also request and

 * response always sent/received in different calls.

 *

 * Synchronous and asynchronous versions of each method are provided.

 *

 * Separate implementations of this class exist for HTTP/1.1 and HTTP/2

 *      Http1Exchange   (HTTP/1.1)

 *      Stream          (HTTP/2)

 *

 * These implementation classes are where work is allocated to threads.

 */

abstract class ExchangeImpl {

    final Exchange exchange;

    ExchangeImpl(Exchange e) {

        this.exchange = e;

    }

    /**

     * Initiates a new exchange and assigns it to a connection if one exists

     * already. connection usually null.

     */

    static ExchangeImpl get(Exchange exchange, HttpConnection connection)

        throws IOException, InterruptedException

    {

        HttpRequestImpl req = exchange.request();

        if (req.version() == HTTP_1_1) {

            return new Http1Exchange(exchange, connection);

        } else {

            Http2ClientImpl c2 = exchange.request().client().client2(); // TODO: improve

            HttpRequestImpl request = exchange.request();

            Http2Connection c = c2.getConnectionFor(request);

            if (c == null) {

                // no existing connection. Send request with HTTP 1 and then

                // upgrade if successful

                ExchangeImpl ex = new Http1Exchange(exchange, connection);

                exchange.h2Upgrade();

                return ex;

            }

            return c.createStream(exchange);

        }

    }

    /* The following methods have separate HTTP/1.1 and HTTP/2 implementations */

    /**

     * Sends the request headers only. May block until all sent.

     */

    abstract void sendHeadersOnly() throws IOException, InterruptedException;

    /**

     * Gets response headers by blocking if necessary. This may be an

     * intermediate response (like 101) or a final response 200 etc.

     */

    abstract HttpResponseImpl getResponse() throws IOException;

    /**

     * Sends a request body after request headers.

     */

    abstract void sendBody() throws IOException, InterruptedException;

    /**

     * Sends the entire request (headers and body) blocking.

     */

    abstract void sendRequest() throws IOException, InterruptedException;

    /**

     * Asynchronous version of sendHeaders().

     */

    abstract CompletableFuture<Void> sendHeadersAsync();

    /**

     * Asynchronous version of getResponse().  Requires void parameter for

     * CompletableFuture chaining.

     */

    abstract CompletableFuture<HttpResponseImpl> getResponseAsync(Void v);

    /**

     * Asynchronous version of sendBody().

     */

    abstract CompletableFuture<Void> sendBodyAsync();

    /**

     * Cancels a request.  Not currently exposed through API.

     */

    abstract void cancel();

    /**

     * Asynchronous version of sendRequest().

     */

    abstract CompletableFuture<Void> sendRequestAsync();

    abstract <T> T responseBody(HttpResponse.BodyProcessor<T> processor)

        throws IOException;

    /**

     * Asynchronous version of responseBody().

     */

    abstract <T> CompletableFuture<T>

    responseBodyAsync(HttpResponse.BodyProcessor<T> processor);

}