/*

 * Copyright (c) 2015, 2017, 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.incubator.http;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.SocketChannel;

import java.util.Arrays;

import java.util.List;

import java.util.concurrent.CompletableFuture;

import javax.net.ssl.SNIHostName;

import javax.net.ssl.SSLContext;

import javax.net.ssl.SSLEngine;

import javax.net.ssl.SSLEngineResult;

import javax.net.ssl.SSLParameters;

import jdk.incubator.http.internal.common.SSLTube;

import jdk.incubator.http.internal.common.Log;

import jdk.incubator.http.internal.common.ExceptionallyCloseable;

import jdk.incubator.http.internal.common.Utils;

/**

 * Asynchronous version of SSLConnection.

 *

 * There are two concrete implementations of this class: AsyncSSLConnection

 * and AsyncSSLTunnelConnection.

 * This abstraction is useful when downgrading from HTTP/2 to HTTP/1.1 over

 * an SSL connection. See ExchangeImpl::get in the case where an ALPNException

 * is thrown.

 *

 * Note: An AsyncSSLConnection wraps a PlainHttpConnection, while an

 *       AsyncSSLTunnelConnection wraps a PlainTunnelingConnection.

 *       If both these wrapped classes where made to inherit from a

 *       common abstraction then it might be possible to merge

 *       AsyncSSLConnection and AsyncSSLTunnelConnection back into

 *       a single class - and simply use different factory methods to

 *       create different wrappees, but this is left up for further cleanup.

 *

 */

abstract class AbstractAsyncSSLConnection extends HttpConnection

    implements ExceptionallyCloseable

{

    protected final SSLEngine engine;

    protected final String serverName;

    protected final SSLParameters sslParameters;

    AbstractAsyncSSLConnection(InetSocketAddress addr,

                               HttpClientImpl client,

                               String serverName,

                               String[] alpn) {

        super(addr, client);

        this.serverName = serverName;

        SSLContext context = client.theSSLContext();

        sslParameters = createSSLParameters(client, context, serverName, alpn);

        Log.logParams(sslParameters);

        engine = createEngine(context, sslParameters);

    }

    abstract HttpConnection plainConnection();

    abstract SSLTube getConnectionFlow();

    final CompletableFuture<String> getALPN() {

        assert connected();

        return getConnectionFlow().getALPN();

    }

    final SSLEngine getEngine() { return engine; }

    private static SSLParameters createSSLParameters(HttpClientImpl client,

                                                     SSLContext context,

                                                     String serverName,

                                                     String[] alpn) {

        SSLParameters sslp = client.sslParameters();

        SSLParameters sslParameters = Utils.copySSLParameters(sslp);

        if (alpn != null) {

            Log.logSSL("AbstractAsyncSSLConnection: Setting application protocols: {0}",

                       Arrays.toString(alpn));

            sslParameters.setApplicationProtocols(alpn);

        } else {

            Log.logSSL("AbstractAsyncSSLConnection: no applications set!");

        }

        if (serverName != null) {

            sslParameters.setServerNames(List.of(new SNIHostName(serverName)));

        }

        return sslParameters;

    }

    private static SSLEngine createEngine(SSLContext context,

                                          SSLParameters sslParameters) {

        SSLEngine engine = context.createSSLEngine();

        engine.setUseClientMode(true);

        engine.setSSLParameters(sslParameters);

        return engine;

    }

    @Override

    final boolean isSecure() {

        return true;

    }

    // Support for WebSocket/RawChannelImpl which unfortunately

    // still depends on synchronous read/writes.

    // It should be removed when RawChannelImpl moves to using asynchronous APIs.

    static final class SSLConnectionChannel extends DetachedConnectionChannel {

        final DetachedConnectionChannel delegate;

        final SSLDelegate sslDelegate;

        SSLConnectionChannel(DetachedConnectionChannel delegate, SSLDelegate sslDelegate) {

            this.delegate = delegate;

            this.sslDelegate = sslDelegate;

        }

        SocketChannel channel() {

            return delegate.channel();

        }

        @Override

        ByteBuffer read() throws IOException {

            SSLDelegate.WrapperResult r = sslDelegate.recvData(ByteBuffer.allocate(8192));

            // TODO: check for closure

            int n = r.result.bytesProduced();

            if (n > 0) {

                return r.buf;

            } else if (n == 0) {

                return Utils.EMPTY_BYTEBUFFER;

            } else {

                return null;

            }

        }

        @Override

        long write(ByteBuffer[] buffers, int start, int number) throws IOException {

            long l = SSLDelegate.countBytes(buffers, start, number);

            SSLDelegate.WrapperResult r = sslDelegate.sendData(buffers, start, number);

            if (r.result.getStatus() == SSLEngineResult.Status.CLOSED) {

                if (l > 0) {

                    throw new IOException("SSLHttpConnection closed");

                }

            }

            return l;

        }

        @Override

        public void shutdownInput() throws IOException {

            delegate.shutdownInput();

        }

        @Override

        public void shutdownOutput() throws IOException {

            delegate.shutdownOutput();

        }

        @Override

        public void close() {

            delegate.close();

        }

    }

    // Support for WebSocket/RawChannelImpl which unfortunately

    // still depends on synchronous read/writes.

    // It should be removed when RawChannelImpl moves to using asynchronous APIs.

    @Override

    DetachedConnectionChannel detachChannel() {

        HttpClientImpl client = client();

        assert client != null;

        DetachedConnectionChannel detachedChannel = plainConnection().detachChannel();

        SSLDelegate sslDelegate = new SSLDelegate(engine,

                                                  detachedChannel.channel(),

                                                  client,

                                                  serverName);

        return new SSLConnectionChannel(detachedChannel, sslDelegate);

    }

}