/*

 * Copyright (c) 2015, 2019, 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;

import java.io.IOException;

import java.net.ConnectException;

import java.net.InetSocketAddress;

import java.net.StandardSocketOptions;

import java.nio.channels.SelectableChannel;

import java.nio.channels.SelectionKey;

import java.nio.channels.SocketChannel;

import java.security.AccessController;

import java.security.PrivilegedActionException;

import java.security.PrivilegedExceptionAction;

import java.time.Duration;

import java.util.concurrent.CompletableFuture;

import jdk.internal.net.http.common.FlowTube;

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

import jdk.internal.net.http.common.MinimalFuture;

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

/**

 * Plain raw TCP connection direct to destination.

 * The connection operates in asynchronous non-blocking mode.

 * All reads and writes are done non-blocking.

 */

class PlainHttpConnection extends HttpConnection {

    private final Object reading = new Object();

    protected final SocketChannel chan;

    private final SocketTube tube; // need SocketTube to call signalClosed().

    private final PlainHttpPublisher writePublisher = new PlainHttpPublisher(reading);

    private volatile boolean connected;

    private boolean closed;

    private volatile ConnectTimerEvent connectTimerEvent;  // may be null

    // should be volatile to provide proper synchronization(visibility) action

    /**

     * Returns a ConnectTimerEvent iff there is a connect timeout duration,

     * otherwise null.

     */

    private ConnectTimerEvent newConnectTimer(Exchange<?> exchange,

                                              CompletableFuture<Void> cf) {

        Duration duration = exchange.remainingConnectTimeout().orElse(null);

        if (duration != null) {

            ConnectTimerEvent cte = new ConnectTimerEvent(duration, exchange, cf);

            return cte;

        }

        return null;

    }

    final class ConnectTimerEvent extends TimeoutEvent {

        private final CompletableFuture<Void> cf;

        private final Exchange<?> exchange;

        ConnectTimerEvent(Duration duration,

                          Exchange<?> exchange,

                          CompletableFuture<Void> cf) {

            super(duration);

            this.exchange = exchange;

            this.cf = cf;

        }

        @Override

        public void handle() {

            if (debug.on()) {

                debug.log("HTTP connect timed out");

            }

            ConnectException ce = new ConnectException("HTTP connect timed out");

            exchange.multi.cancel(ce);

            client().theExecutor().execute(() -> cf.completeExceptionally(ce));

        }

        @Override

        public String toString() {

            return "ConnectTimerEvent, " + super.toString();

        }

    }

    final class ConnectEvent extends AsyncEvent {

        private final CompletableFuture<Void> cf;

        ConnectEvent(CompletableFuture<Void> cf) {

            this.cf = cf;

        }

        @Override

        public SelectableChannel channel() {

            return chan;

        }

        @Override

        public int interestOps() {

            return SelectionKey.OP_CONNECT;

        }

        @Override

        public void handle() {

            try {

                assert !connected : "Already connected";

                assert !chan.isBlocking() : "Unexpected blocking channel";

                if (debug.on())

                    debug.log("ConnectEvent: finishing connect");

                boolean finished = chan.finishConnect();

                assert finished : "Expected channel to be connected";

                if (debug.on())

                    debug.log("ConnectEvent: connect finished: %s Local addr: %s",

                              finished, chan.getLocalAddress());

                // complete async since the event runs on the SelectorManager thread

                cf.completeAsync(() -> null, client().theExecutor());

            } catch (Throwable e) {

                Throwable t = Utils.toConnectException(e);

                client().theExecutor().execute( () -> cf.completeExceptionally(t));

                close();

            }

        }

        @Override

        public void abort(IOException ioe) {

            client().theExecutor().execute( () -> cf.completeExceptionally(ioe));

            close();

        }

    }

    @Override

    public CompletableFuture<Void> connectAsync(Exchange<?> exchange) {

        CompletableFuture<Void> cf = new MinimalFuture<>();

        try {

            assert !connected : "Already connected";

            assert !chan.isBlocking() : "Unexpected blocking channel";

            boolean finished;

            connectTimerEvent = newConnectTimer(exchange, cf);

            if (connectTimerEvent != null) {

                if (debug.on())

                    debug.log("registering connect timer: " + connectTimerEvent);

                client().registerTimer(connectTimerEvent);

            }

            PrivilegedExceptionAction<Boolean> pa =

                    () -> chan.connect(Utils.resolveAddress(address));

            try {

                 finished = AccessController.doPrivileged(pa);

            } catch (PrivilegedActionException e) {

               throw e.getCause();

            }

            if (finished) {

                if (debug.on()) debug.log("connect finished without blocking");

                cf.complete(null);

            } else {

                if (debug.on()) debug.log("registering connect event");

                client().registerEvent(new ConnectEvent(cf));

            }

        } catch (Throwable throwable) {

            cf.completeExceptionally(Utils.toConnectException(throwable));

            try {

                close();

            } catch (Exception x) {

                if (debug.on())

                    debug.log("Failed to close channel after unsuccessful connect");

            }

        }

        return cf;

    }

    @Override

    public CompletableFuture<Void> finishConnect() {

        assert connected == false;

        if (debug.on()) debug.log("finishConnect, setting connected=true");

        connected = true;

        if (connectTimerEvent != null)

            client().cancelTimer(connectTimerEvent);

        return MinimalFuture.completedFuture(null);

    }

    @Override

    SocketChannel channel() {

        return chan;

    }

    @Override

    final FlowTube getConnectionFlow() {

        return tube;

    }

    PlainHttpConnection(InetSocketAddress addr, HttpClientImpl client) {

        super(addr, client);

        try {

            this.chan = SocketChannel.open();

            chan.configureBlocking(false);

            trySetReceiveBufferSize(client.getReceiveBufferSize());

            if (debug.on()) {

                int bufsize = getInitialBufferSize();

                debug.log("Initial receive buffer size is: %d", bufsize);

            }

            chan.setOption(StandardSocketOptions.TCP_NODELAY, true);

            // wrap the channel in a Tube for async reading and writing

            tube = new SocketTube(client(), chan, Utils::getBuffer);

        } catch (IOException e) {

            throw new InternalError(e);

        }

    }

    private int getInitialBufferSize() {

        try {

            return chan.getOption(StandardSocketOptions.SO_RCVBUF);

        } catch(IOException x) {

            if (debug.on())

                debug.log("Failed to get initial receive buffer size on %s", chan);

        }

        return 0;

    }

    private void trySetReceiveBufferSize(int bufsize) {

        try {

            if (bufsize > 0) {

                chan.setOption(StandardSocketOptions.SO_RCVBUF, bufsize);

            }

        } catch(IOException x) {

            if (debug.on())

                debug.log("Failed to set receive buffer size to %d on %s",

                          bufsize, chan);

        }

    }

    @Override

    HttpPublisher publisher() { return writePublisher; }

    @Override

    public String toString() {

        return "PlainHttpConnection: " + super.toString();

    }

    /**

     * Closes this connection

     */

    @Override

    public void close() {

        synchronized (this) {

            if (closed) {

                return;

            }

            closed = true;

        }

        try {

            Log.logTrace("Closing: " + toString());

            if (debug.on())

                debug.log("Closing channel: " + client().debugInterestOps(chan));

            if (connectTimerEvent != null)

                client().cancelTimer(connectTimerEvent);

            chan.close();

            tube.signalClosed();

        } catch (IOException e) {

            Log.logTrace("Closing resulted in " + e);

        }

    }

    @Override

    ConnectionPool.CacheKey cacheKey() {

        return new ConnectionPool.CacheKey(address, null);

    }

    @Override

    synchronized boolean connected() {

        return connected;

    }

    @Override

    boolean isSecure() {

        return false;

    }

    @Override

    boolean isProxied() {

        return false;

    }

}