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 * Copyright (c) 2015, 2020, 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
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 */

package jdk.internal.net.http;

import java.io.IOException;
import java.net.URI;
import java.nio.ByteBuffer;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.function.Supplier;
import javax.net.ssl.SSLSession;
import java.net.http.HttpClient;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import jdk.internal.net.http.websocket.RawChannel;

The implementation class for HttpResponse
/**
 * The implementation class for HttpResponse
 */
class HttpResponseImpl<T> implements HttpResponse<T>, RawChannel.Provider {

    final int responseCode;
    final HttpRequest initialRequest;
    final Optional<HttpResponse<T>> previousResponse;
    final HttpHeaders headers;
    final Optional<SSLSession> sslSession;
    final URI uri;
    final HttpClient.Version version;
    final RawChannelProvider rawChannelProvider;
    final T body;

    public HttpResponseImpl(HttpRequest initialRequest,
                            Response response,
                            HttpResponse<T> previousResponse,
                            T body,
                            Exchange<T> exch) {
        this.responseCode = response.statusCode();
        this.initialRequest = initialRequest;
        this.previousResponse = Optional.ofNullable(previousResponse);
        this.headers = response.headers();
        //this.trailers = trailers;
        this.sslSession = Optional.ofNullable(response.getSSLSession());
        this.uri = response.request().uri();
        this.version = response.version();
        this.rawChannelProvider = RawChannelProvider.create(response, exch);
        this.body = body;
    }

    @Override
    public int statusCode() {
        return responseCode;
    }

    @Override
    public HttpRequest request() {
        return initialRequest;
    }

    @Override
    public Optional<HttpResponse<T>> previousResponse() {
        return previousResponse;
    }

    @Override
    public HttpHeaders headers() {
        return headers;
    }

    @Override
    public T body() {
        return body;
    }

    @Override
    public Optional<SSLSession> sslSession() {
        return sslSession;
    }

    @Override
    public URI uri() {
        return uri;
    }

    @Override
    public HttpClient.Version version() {
        return version;
    }
    // keepalive flag determines whether connection is closed or kept alive
    // by reading/skipping data

    
Returns a RawChannel that may be used for WebSocket protocol.
Throws:
UnsupportedOperationException – if getting a RawChannel over
        this connection is not supported.
IOException – if an I/O exception occurs while retrieving
        the channel.
Implementation Note:
This implementation does not support RawChannel over
          HTTP/2 connections.
Returns:
a RawChannel that may be used for WebSocket protocol./**
     * Returns a RawChannel that may be used for WebSocket protocol.
     * @implNote This implementation does not support RawChannel over
     *           HTTP/2 connections.
     * @return a RawChannel that may be used for WebSocket protocol.
     * @throws UnsupportedOperationException if getting a RawChannel over
     *         this connection is not supported.
     * @throws IOException if an I/O exception occurs while retrieving
     *         the channel.
     */
    @Override
    public synchronized RawChannel rawChannel() throws IOException {
        if (rawChannelProvider == null) {
            throw new UnsupportedOperationException(
                    "RawChannel is only supported for WebSocket creation");
        }
        return rawChannelProvider.rawChannel();
    }

    
Closes the RawChannel that may have been used for WebSocket protocol.
Throws:
UnsupportedOperationException – if getting a RawChannel over
        this connection is not supported.
IOException – if an I/O exception occurs while closing
        the channel.
API Note:
This method should be called to close the connection if an exception occurs during the websocket handshake, in cases where rawChannel().close() would have been called. An unsuccessful handshake may prevent the creation of the RawChannel: if a RawChannel has already been created, this method wil close it. Otherwise, it will close the connection./**
     * Closes the RawChannel that may have been used for WebSocket protocol.
     *
     * @apiNote This method should be called to close the connection
     * if an exception occurs during the websocket handshake, in cases where
     * {@link #rawChannel() rawChannel().close()} would have been called.
     * An unsuccessful handshake may prevent the creation of the RawChannel:
     * if a RawChannel has already been created, this method wil close it.
     * Otherwise, it will close the connection.
     *
     * @throws UnsupportedOperationException if getting a RawChannel over
     *         this connection is not supported.
     * @throws IOException if an I/O exception occurs while closing
     *         the channel.
     */
    @Override
    public synchronized void closeRawChannel() throws IOException {
        if (rawChannelProvider == null) {
            throw new UnsupportedOperationException(
                    "RawChannel is only supported for WebSocket creation");
        }
        rawChannelProvider.closeRawChannel();
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        String method = request().method();
        URI uri = request().uri();
        String uristring = uri == null ? "" : uri.toString();
        sb.append('(')
          .append(method)
          .append(" ")
          .append(uristring)
          .append(") ")
          .append(statusCode());
        return sb.toString();
    }

    
An auxiliary class used for RawChannel creation when creating a WebSocket.
This avoids keeping around references to connection/exchange in the
regular HttpResponse case. Only those responses corresponding to an
initial WebSocket request have a RawChannelProvider.
/**
     * An auxiliary class used for RawChannel creation when creating a WebSocket.
     * This avoids keeping around references to connection/exchange in the
     * regular HttpResponse case. Only those responses corresponding to an
     * initial WebSocket request have a RawChannelProvider.
     */
    private static final class RawChannelProvider implements RawChannel.Provider {
        private final HttpConnection connection;
        private final Exchange<?> exchange;
        private RawChannel rawchan;
        RawChannelProvider(HttpConnection conn, Exchange<?> exch) {
            connection = conn;
            exchange = exch;
        }

        static RawChannelProvider create(Response resp, Exchange<?> exch) {
            if (resp.request().isWebSocket()) {
                return new RawChannelProvider(connection(resp, exch), exch);
            }
            return null;
        }

        @Override
        public synchronized RawChannel rawChannel() {
            if (rawchan == null) {
                ExchangeImpl<?> exchImpl = exchangeImpl();
                if (!(exchImpl instanceof Http1Exchange)) {
                    // RawChannel is only used for WebSocket - and WebSocket
                    // is not supported over HTTP/2 yet, so we should not come
                    // here. Getting a RawChannel over HTTP/2 might be supported
                    // in the future, but it would entail retrieving any left over
                    // bytes that might have been read but not consumed by the
                    // HTTP/2 connection.
                    throw new UnsupportedOperationException("RawChannel is not supported over HTTP/2");
                }
                // Http1Exchange may have some remaining bytes in its
                // internal buffer.
                Supplier<ByteBuffer> initial = ((Http1Exchange<?>) exchImpl)::drainLeftOverBytes;
                rawchan = new RawChannelTube(connection, initial);
            }
            return rawchan;
        }

        public synchronized void closeRawChannel() throws IOException {
            //  close the rawChannel, if created, or the
            // connection, if not.
            if (rawchan != null) rawchan.close();
            else connection.close();
        }

        private static HttpConnection connection(Response resp, Exchange<?> exch) {
            if (exch == null || exch.exchImpl == null) {
                assert resp.statusCode == 407;
                return null; // case of Proxy 407
            }
            return exch.exchImpl.connection();
        }

        private ExchangeImpl<?> exchangeImpl() {
            return exchange != null ? exchange.exchImpl : null;
        }

    }
}