/*
    * ====================================================================
    * 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.hc.core5.http.nio.support;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.List;
  
  import org.apache.hc.core5.concurrent.FutureCallback;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.nio.AsyncPushConsumer;
  import org.apache.hc.core5.http.nio.AsyncResponseConsumer;
  import org.apache.hc.core5.http.nio.CapacityChannel;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  
  /**
   * Abstract push response handler.
   *
   * @since 5.0
   *
   * @param <T> response message representation.
   */
  public abstract class AbstractAsyncPushHandler<T> implements AsyncPushConsumer {
  
      private final AsyncResponseConsumer<T> responseConsumer;
  
      public AbstractAsyncPushHandler(final AsyncResponseConsumer<T> responseConsumer) {
          this.responseConsumer = Args.notNull(responseConsumer, "Response consumer");
      }
  
      /**
       * Triggered to handle the push message with the given promised request.
       *
       * @param promise the promised request message.
       * @param responseMessage the pushed response message.
       */
      protected abstract void handleResponse(
              final HttpRequest promise, final T responseMessage) throws IOException, HttpException;
  
      /**
       * Triggered to handle the exception thrown while processing a push response.
       *
       * @param promise the promised request message.
       * @param cause the cause of error.
       */
      protected void handleError(final HttpRequest promise, final Exception cause) {
      }
  
      @Override
      public final void consumePromise(
              final HttpRequest promise,
              final HttpResponse response,
              final EntityDetails entityDetails,
              final HttpContext httpContext) throws HttpException, IOException {
          responseConsumer.consumeResponse(response, entityDetails, httpContext, new FutureCallback<T>() {
  
              @Override
              public void completed(final T result) {
                  try {
                      handleResponse(promise, result);
                  } catch (final Exception ex) {
                      failed(ex);
                  }
              }
  
              @Override
              public void failed(final Exception cause) {
                  handleError(promise, cause);
                  releaseResources();
              }
 
             @Override
             public void cancelled() {
                 releaseResources();
             }
 
         });
     }
 
     @Override
     public final void updateCapacity(final CapacityChannel capacityChannel) throws IOException {
         responseConsumer.updateCapacity(capacityChannel);
     }
 
     @Override
     public final void consume(final ByteBuffer src) throws IOException {
         responseConsumer.consume(src);
     }
 
     @Override
     public final void streamEnd(final List<? extends Header> trailers) throws HttpException, IOException {
         responseConsumer.streamEnd(trailers);
     }
 
     @Override
     public final void failed(final Exception cause) {
         responseConsumer.failed(cause);
         releaseResources();
     }
 
     @Override
     public final void releaseResources() {
         if (responseConsumer != null) {
             responseConsumer.releaseResources();
         }
     }
 
 }