/*
    * ====================================================================
    * 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.impl.cache;
  
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  
  import org.apache.hc.client5.http.cache.HeaderConstants;
  import org.apache.hc.client5.http.cache.HttpCacheEntry;
  import org.apache.hc.client5.http.cache.Resource;
  import org.apache.hc.client5.http.cache.ResourceFactory;
  import org.apache.hc.client5.http.cache.ResourceIOException;
  import org.apache.hc.client5.http.utils.DateUtils;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.HttpStatus;
  import org.apache.hc.core5.http.message.HeaderGroup;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.ByteArrayBuffer;
  
  /**
   * Creates new {@link HttpCacheEntry}s and updates existing ones with new or updated information
   * based on the response from the origin server.
   */
  class CacheUpdateHandler {
  
      private final ResourceFactory resourceFactory;
  
      CacheUpdateHandler() {
          this(new HeapResourceFactory());
      }
  
      CacheUpdateHandler(final ResourceFactory resourceFactory) {
          super();
          this.resourceFactory = resourceFactory;
      }
  
      /**
       * Creates a cache entry for the given request, origin response message and response content.
       */
      public HttpCacheEntry createtCacheEntry(
              final HttpRequest request,
              final HttpResponse originResponse,
              final ByteArrayBuffer content,
              final Date requestSent,
              final Date responseReceived) throws ResourceIOException {
          return new HttpCacheEntry(
                  requestSent,
                  responseReceived,
                  originResponse.getCode(),
                  originResponse.getHeaders(),
                  content != null ? resourceFactory.generate(request.getRequestUri(), content.array(), 0, content.length()) : null);
      }
  
      /**
       * Update the entry with the new information from the response.  Should only be used for
       * 304 responses.
       */
      public HttpCacheEntry updateCacheEntry(
              final String requestId,
              final HttpCacheEntry entry,
              final Date requestDate,
              final Date responseDate,
              final HttpResponse response) throws ResourceIOException {
          Args.check(response.getCode() == HttpStatus.SC_NOT_MODIFIED,
                  "Response must have 304 status code");
          final Header[] mergedHeaders = mergeHeaders(entry, response);
          Resource resource = null;
          if (entry.getResource() != null) {
              resource = resourceFactory.copy(requestId, entry.getResource());
          }
         return new HttpCacheEntry(
                 requestDate,
                 responseDate,
                 entry.getStatus(),
                 mergedHeaders,
                 resource);
     }
 
     public HttpCacheEntry updateParentCacheEntry(
             final String requestId,
             final HttpCacheEntry existing,
             final HttpCacheEntry entry,
             final String variantKey,
             final String variantCacheKey) throws ResourceIOException {
         HttpCacheEntry src = existing;
         if (src == null) {
             src = entry;
         }
 
         Resource resource = null;
         if (src.getResource() != null) {
             resource = resourceFactory.copy(requestId, src.getResource());
         }
         final Map<String,String> variantMap = new HashMap<>(src.getVariantMap());
         variantMap.put(variantKey, variantCacheKey);
         return new HttpCacheEntry(
                 src.getRequestDate(),
                 src.getResponseDate(),
                 src.getStatus(),
                 src.getHeaders(),
                 resource,
                 variantMap);
     }
 
     private Header[] mergeHeaders(final HttpCacheEntry entry, final HttpResponse response) {
         if (DateUtils.isAfter(entry, response, HttpHeaders.DATE)) {
             return entry.getHeaders();
         }
         final HeaderGroup headerGroup = new HeaderGroup();
         headerGroup.setHeaders(entry.getHeaders());
         // Remove cache headers that match response
         for (final Iterator<Header> it = response.headerIterator(); it.hasNext(); ) {
             final Header responseHeader = it.next();
             // Since we do not expect a content in a 304 response, should retain the original Content-Encoding header
             if (HttpHeaders.CONTENT_ENCODING.equals(responseHeader.getName())
                     || HttpHeaders.CONTENT_LENGTH.equals(responseHeader.getName())) {
                 continue;
             }
             headerGroup.removeHeaders(responseHeader.getName());
         }
         // remove cache entry 1xx warnings
         for (final Iterator<Header> it = headerGroup.headerIterator(); it.hasNext(); ) {
             final Header cacheHeader = it.next();
             if (HeaderConstants.WARNING.equalsIgnoreCase(cacheHeader.getName())) {
                 final String warningValue = cacheHeader.getValue();
                 if (warningValue != null && warningValue.startsWith("1")) {
                     it.remove();
                 }
             }
         }
         for (final Iterator<Header> it = response.headerIterator(); it.hasNext(); ) {
             final Header responseHeader = it.next();
             // Since we do not expect a content in a 304 response, should update the cache entry with Content-Encoding
             if (HttpHeaders.CONTENT_ENCODING.equals(responseHeader.getName())
                     || HttpHeaders.CONTENT_LENGTH.equals(responseHeader.getName())) {
                 continue;
             }
             headerGroup.addHeader(responseHeader);
         }
         return headerGroup.getHeaders();
     }
 
 }