/*
    * ====================================================================
    * 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.entity;
  
  import java.io.IOException;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.UnsupportedCharsetException;
  
  import org.apache.hc.core5.concurrent.FutureCallback;
  import org.apache.hc.core5.http.ContentType;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.config.CharCodingConfig;
  import org.apache.hc.core5.http.nio.AsyncEntityConsumer;
  import org.apache.hc.core5.util.Args;
  
  /**
   * Abstract text entity content consumer.
   *
   * @since 5.0
   *
   * @param <T> entity representation.
   */
  public abstract class AbstractCharAsyncEntityConsumer<T> extends AbstractCharDataConsumer implements AsyncEntityConsumer<T> {
  
      private volatile FutureCallback<T> resultCallback;
      private volatile T content;
  
      protected AbstractCharAsyncEntityConsumer(final int bufSize, final CharCodingConfig charCodingConfig) {
          super(bufSize, charCodingConfig);
      }
  
      public AbstractCharAsyncEntityConsumer() {
      }
  
      /**
       * Triggered to signal beginning of entity content stream.
       *
       * @param contentType the entity content type
       */
      protected abstract void streamStart(ContentType contentType) throws HttpException, IOException;
  
      /**
       * Triggered to generate entity representation.
       *
       * @return the entity content
       */
      protected abstract T generateContent() throws IOException;
  
      @Override
      public final void streamStart(
              final EntityDetails entityDetails,
              final FutureCallback<T> resultCallback) throws IOException, HttpException {
          Args.notNull(resultCallback, "Result callback");
          this.resultCallback = resultCallback;
          try {
              final ContentType contentType = entityDetails != null ? ContentType.parse(entityDetails.getContentType()) : null;
              setCharset(contentType != null ? contentType.getCharset() : null);
              streamStart(contentType);
          } catch (final UnsupportedCharsetException ex) {
              throw new UnsupportedEncodingException(ex.getMessage());
          }
      }
  
      @Override
      protected final void completed() throws IOException {
          content = generateContent();
          if (resultCallback != null) {
              resultCallback.completed(content);
          }
          releaseResources();
      }
  
      @Override
      public final void failed(final Exception cause) {
         if (resultCallback != null) {
             resultCallback.failed(cause);
         }
         releaseResources();
     }
 
     @Override
     public final T getContent() {
         return content;
     }
 
 }