/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.http.impl.nio.reactor;
  
  import java.io.IOException;
  import java.net.SocketAddress;
  import java.nio.channels.Channel;
  import java.nio.channels.SelectionKey;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.http.annotation.Contract;
  import org.apache.http.annotation.ThreadingBehavior;
  import org.apache.http.nio.reactor.IOSession;
  import org.apache.http.nio.reactor.SessionRequest;
  import org.apache.http.nio.reactor.SessionRequestCallback;
  import org.apache.http.util.Args;
  
  /**
   * Default implementation of {@link SessionRequest}.
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
  public class SessionRequestImpl implements SessionRequest {
  
      enum SessionRequestState {
          ACTIVE,
          SUCCESSFUL,
          TIMEDOUT,
          CANCELLED,
          FAILED,
      }
  
      private final SocketAddress remoteAddress;
      private final SocketAddress localAddress;
      private final Object attachment;
      private final SessionRequestCallback callback;
      private final AtomicReference<SessionRequestState> state;
  
      private volatile SelectionKey key;
  
      private volatile int connectTimeout;
      private volatile IOSession session = null;
      private volatile IOException exception = null;
  
      public SessionRequestImpl(
              final SocketAddress remoteAddress,
              final SocketAddress localAddress,
              final Object attachment,
              final SessionRequestCallback callback) {
          super();
          Args.notNull(remoteAddress, "Remote address");
          this.remoteAddress = remoteAddress;
          this.localAddress = localAddress;
          this.attachment = attachment;
          this.callback = callback;
          this.state = new AtomicReference<SessionRequestState>(SessionRequestState.ACTIVE);
      }
  
      @Override
      public SocketAddress getRemoteAddress() {
          return this.remoteAddress;
      }
  
      @Override
      public SocketAddress getLocalAddress() {
          return this.localAddress;
      }
  
      @Override
      public Object getAttachment() {
          return this.attachment;
      }
  
     @Override
     public boolean isCompleted() {
         return this.state.get().compareTo(SessionRequestState.ACTIVE) != 0;
     }
 
     boolean isTerminated() {
         return this.state.get().compareTo(SessionRequestState.SUCCESSFUL) > 0;
     }
 
     protected void setKey(final SelectionKey key) {
         this.key = key;
         if (this.isCompleted()) {
             key.cancel();
             final Channel channel = key.channel();
             if (channel.isOpen()) {
                 try {
                     channel.close();
                 } catch (final IOException ignore) {}
             }
         }
     }
 
     @Override
     public void waitFor() throws InterruptedException {
         if (this.isCompleted()) {
             return;
         }
         synchronized (this) {
             while (!this.isCompleted()) {
                 wait();
             }
         }
     }
 
     @Override
     public IOSession getSession() {
         synchronized (this) {
             return this.session;
         }
     }
 
     @Override
     public IOException getException() {
         synchronized (this) {
             return this.exception;
         }
     }
 
     public void completed(final IOSession session) {
         Args.notNull(session, "Session");
         if (this.state.compareAndSet(SessionRequestState.ACTIVE, SessionRequestState.SUCCESSFUL)) {
             synchronized (this) {
                 this.session = session;
                 if (this.callback != null) {
                     this.callback.completed(this);
                 }
                 notifyAll();
             }
         }
     }
 
     public void failed(final IOException exception) {
         if (exception == null) {
             return;
         }
         if (this.state.compareAndSet(SessionRequestState.ACTIVE, SessionRequestState.FAILED)) {
             final SelectionKey key = this.key;
             if (key != null) {
                 key.cancel();
                 final Channel channel = key.channel();
                 try {
                     channel.close();
                 } catch (final IOException ignore) {}
             }
             synchronized (this) {
                 this.exception = exception;
                 if (this.callback != null) {
                     this.callback.failed(this);
                 }
                 notifyAll();
             }
         }
     }
 
     public void timeout() {
         if (this.state.compareAndSet(SessionRequestState.ACTIVE, SessionRequestState.TIMEDOUT)) {
             final SelectionKey key = this.key;
             if (key != null) {
                 key.cancel();
                 final Channel channel = key.channel();
                 if (channel.isOpen()) {
                     try {
                         channel.close();
                     } catch (final IOException ignore) {}
                 }
             }
             synchronized (this) {
                 if (this.callback != null) {
                     this.callback.timeout(this);
                 }
             }
         }
     }
 
     @Override
     public int getConnectTimeout() {
         return this.connectTimeout;
     }
 
     @Override
     public void setConnectTimeout(final int timeout) {
         if (this.connectTimeout != timeout) {
             this.connectTimeout = timeout;
             final SelectionKey key = this.key;
             if (key != null) {
                 key.selector().wakeup();
             }
         }
     }
 
     @Override
     public void cancel() {
         if (this.state.compareAndSet(SessionRequestState.ACTIVE, SessionRequestState.CANCELLED)) {
             final SelectionKey key = this.key;
             if (key != null) {
                 key.cancel();
                 final Channel channel = key.channel();
                 if (channel.isOpen()) {
                     try {
                         channel.close();
                     } catch (final IOException ignore) {}
                 }
             }
             synchronized (this) {
                 if (this.callback != null) {
                     this.callback.cancelled(this);
                 }
                 notifyAll();
             }
         }
     }
 
 }