/*
    * ====================================================================
    * 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.impl;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.ContentLengthStrategy;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HeaderElements;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpMessage;
  import org.apache.hc.core5.http.NotImplementedException;
  import org.apache.hc.core5.http.ProtocolException;
  import org.apache.hc.core5.http.message.MessageSupport;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.TextUtils;
  
  /**
   * The default implementation of the content length strategy. This class
   * will throw {@link ProtocolException} if it encounters an unsupported
   * transfer encoding, multiple {@code Content-Length} header
   * values or a malformed {@code Content-Length} header value.
   * <p>
   * This class recognizes "chunked" transfer-coding only.
   *
   * @since 5.0
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE)
  public class DefaultContentLengthStrategy implements ContentLengthStrategy {
  
      public static final DefaultContentLengthStrategy INSTANCE = new DefaultContentLengthStrategy();
  
      /**
       * Creates {@code DefaultContentLengthStrategy} instance. {@link ContentLengthStrategy#UNDEFINED}
       * is used per default when content length is not explicitly specified in the message.
       */
      public DefaultContentLengthStrategy() {
      }
  
      enum Coding { UNKNOWN, CHUNK }
  
      @Override
      public long determineLength(final HttpMessage message) throws HttpException {
          Args.notNull(message, "HTTP message");
          final Header teh = message.getFirstHeader(HttpHeaders.TRANSFER_ENCODING);
          if (teh != null) {
              final AtomicReference<Coding> codingRef = new AtomicReference<>();
              MessageSupport.parseTokens(message, HttpHeaders.TRANSFER_ENCODING, e -> {
                  if (!TextUtils.isBlank(e)) {
                      if (e.equalsIgnoreCase(HeaderElements.CHUNKED_ENCODING)) {
                          if (!codingRef.compareAndSet(null, Coding.CHUNK)) {
                              codingRef.set(Coding.UNKNOWN);
                          }
                      } else {
                          codingRef.set(Coding.UNKNOWN);
                      }
                  }
              });
              if (codingRef.get() == Coding.CHUNK) {
                  return CHUNKED;
              }
              throw new NotImplementedException("Unsupported transfer encoding: " + teh.getValue());
          }
          if (message.countHeaders(HttpHeaders.CONTENT_LENGTH) > 1) {
              throw new ProtocolException("Multiple Content-Length headers");
          }
          final Header contentLengthHeader = message.getFirstHeader(HttpHeaders.CONTENT_LENGTH);
          if (contentLengthHeader != null) {
              final String s = contentLengthHeader.getValue();
              try {
                  final long len = Long.parseLong(s);
                 if (len < 0) {
                     throw new ProtocolException("Negative content length: " + s);
                 }
                 return len;
             } catch (final NumberFormatException e) {
                 throw new ProtocolException("Invalid content length: " + s);
             }
         }
         return UNDEFINED;
     }
 
 }