/*
    * ====================================================================
    * 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.client5.http.async.methods;
  
  import java.io.IOException;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  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.HttpResponse;
  import org.apache.hc.core5.http.nio.AsyncResponseConsumer;
  import org.apache.hc.core5.http.nio.entity.AbstractCharDataConsumer;
  import org.apache.hc.core5.http.protocol.HttpContext;
  
  /**
   * Abstract response consumer that processes response body data as a character stream.
   *
   * @since 5.0
   *
   * @param <T> response message representation.
   */
  public abstract class AbstractCharResponseConsumer<T> extends AbstractCharDataConsumer implements AsyncResponseConsumer<T> {
  
      private volatile FutureCallback<T> resultCallback;
  
      /**
       * Triggered to signal the beginning of data processing.
       *
       * @param response the response message head
       * @param contentType the content type of the response body,
       *                    or {@code null} if the response does not enclose a response entity.
       */
      protected abstract void start(HttpResponse response, ContentType contentType) throws HttpException, IOException;
  
      /**
       * Triggered to generate object that represents a result of response message processing.
       *
       * @return the result of response processing.
       */
      protected abstract T buildResult() throws IOException;
  
      @Override
      public void informationResponse(
              final HttpResponse response,
              final HttpContext context) throws HttpException, IOException {
      }
  
      @Override
      public final void consumeResponse(
              final HttpResponse response,
              final EntityDetails entityDetails,
              final HttpContext context,
              final FutureCallback<T> resultCallback) throws HttpException, IOException {
          this.resultCallback = resultCallback;
          if (entityDetails != null) {
              final ContentType contentType;
              try {
                  contentType = ContentType.parse(entityDetails.getContentType());
              } catch (final UnsupportedCharsetException ex) {
                  throw new UnsupportedEncodingException(ex.getMessage());
              }
              Charset charset = contentType != null ? contentType.getCharset() : null;
              if (charset == null) {
                  charset = StandardCharsets.US_ASCII;
              }
              setCharset(charset);
              start(response, contentType != null ? contentType : ContentType.DEFAULT_TEXT);
          } else {
              start(response, null);
              completed();
         }
     }
 
     @Override
     protected final void completed() throws IOException {
         resultCallback.completed(buildResult());
     }
 
     @Override
     public void failed(final Exception cause) {
     }
 
 }