/*
    * ====================================================================
    * 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.conn;
  
  import java.io.IOException;
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Proxy;
  
  import org.apache.http.HttpClientConnection;
  import org.apache.http.HttpConnection;
  import org.apache.http.annotation.NotThreadSafe;
  import org.apache.http.conn.ManagedHttpClientConnection;
  import org.apache.http.protocol.HttpContext;
  
  /**
   * @since 4.3
   */
  @NotThreadSafe
  class CPoolProxy implements InvocationHandler {
  
      private static final Method CLOSE_METHOD;
      private static final Method SHUTDOWN_METHOD;
      private static final Method IS_OPEN_METHOD;
      private static final Method IS_STALE_METHOD;
  
      static {
          try {
              CLOSE_METHOD = HttpConnection.class.getMethod("close");
              SHUTDOWN_METHOD = HttpConnection.class.getMethod("shutdown");
              IS_OPEN_METHOD = HttpConnection.class.getMethod("isOpen");
              IS_STALE_METHOD = HttpConnection.class.getMethod("isStale");
          } catch (final NoSuchMethodException ex) {
              throw new Error(ex);
          }
      }
  
      private volatile CPoolEntry poolEntry;
  
      CPoolProxy(final CPoolEntry entry) {
          super();
          this.poolEntry = entry;
      }
  
      CPoolEntry getPoolEntry() {
          return this.poolEntry;
      }
  
      CPoolEntry detach() {
          final CPoolEntry local = this.poolEntry;
          this.poolEntry = null;
          return local;
      }
  
      HttpClientConnection getConnection() {
          final CPoolEntry local = this.poolEntry;
          if (local == null) {
              return null;
          }
          return local.getConnection();
      }
  
      public void close() throws IOException {
          final CPoolEntry local = this.poolEntry;
          if (local != null) {
              local.closeConnection();
          }
      }
  
      public void shutdown() throws IOException {
          final CPoolEntry local = this.poolEntry;
          if (local != null) {
              local.shutdownConnection();
          }
     }
 
     public boolean isOpen() {
         final CPoolEntry local = this.poolEntry;
         if (local != null) {
             return !local.isClosed();
         } else {
             return false;
         }
     }
 
     public boolean isStale() {
         final HttpClientConnection conn = getConnection();
         if (conn != null) {
             return conn.isStale();
         } else {
             return true;
         }
     }
 
     public Object invoke(
             final Object proxy, final Method method, final Object[] args) throws Throwable {
         if (method.equals(CLOSE_METHOD)) {
             close();
             return null;
         } else if (method.equals(SHUTDOWN_METHOD)) {
             shutdown();
             return null;
         } else if (method.equals(IS_OPEN_METHOD)) {
             return Boolean.valueOf(isOpen());
         } else if (method.equals(IS_STALE_METHOD)) {
             return Boolean.valueOf(isStale());
         } else {
             final HttpClientConnection conn = getConnection();
             if (conn == null) {
                 throw new ConnectionShutdownException();
             }
             try {
                 return method.invoke(conn, args);
             } catch (final InvocationTargetException ex) {
                 final Throwable cause = ex.getCause();
                 if (cause != null) {
                     throw cause;
                 } else {
                     throw ex;
                 }
             }
         }
     }
 
     public static HttpClientConnection newProxy(
             final CPoolEntry poolEntry) {
         return (HttpClientConnection) Proxy.newProxyInstance(
                 CPoolProxy.class.getClassLoader(),
                 new Class<?>[] { ManagedHttpClientConnection.class, HttpContext.class },
                 new CPoolProxy(poolEntry));
     }
 
     private static CPoolProxy getHandler(
             final HttpClientConnection proxy) {
         final InvocationHandler handler = Proxy.getInvocationHandler(proxy);
         if (!CPoolProxy.class.isInstance(handler)) {
             throw new IllegalStateException("Unexpected proxy handler class: " + handler);
         }
         return CPoolProxy.class.cast(handler);
     }
 
     public static CPoolEntry getPoolEntry(final HttpClientConnection proxy) {
         final CPoolEntry entry = getHandler(proxy).getPoolEntry();
         if (entry == null) {
             throw new ConnectionShutdownException();
         }
         return entry;
     }
 
     public static CPoolEntry detach(final HttpClientConnection proxy) {
         return getHandler(proxy).detach();
     }
 
 }