/**
    * This file Copyright (c) 2003-2017 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.virtualuri;
  
  import info.magnolia.cms.core.AggregationState;
  import info.magnolia.cms.filters.AbstractMgnlFilter;
  import info.magnolia.cms.util.RequestDispatchUtil;
  
  import java.io.IOException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.Optional;
  
  import javax.inject.Inject;
  import javax.inject.Provider;
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Handle redirects configured using {@link VirtualUriMapping VirtualUriMappings}.
   *
   * @see VirtualUriMapping
   */
  public class VirtualUriFilter extends AbstractMgnlFilter {
  
      private static final Logger log = LoggerFactory.getLogger(VirtualUriFilter.class);
  
      private VirtualUriRegistry registry;
      private Provider<AggregationState> aggregationStateProvider;
  
      @Inject
      public VirtualUriFilter(VirtualUriRegistry registry, Provider<AggregationState> aggregationStateProvider) {
          this.registry = registry;
          this.aggregationStateProvider = aggregationStateProvider;
      }
  
      @Override
      public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
              throws IOException, ServletException {
  
          final AggregationState aggregationState = aggregationStateProvider.get();
          String currentUri = aggregationState.getCurrentURI();
          String queryString = aggregationState.getQueryString();
  
          // Encapsulate pre-decoded handle/path-info (that is without context path) + query string into a relative URI
          final URI uri;
          try {
              uri = new URI(null, null, currentUri, queryString, null);
          } catch (URISyntaxException e) {
              log.warn("Cannot reconstruct a valid URI from the aggregation state data", e);
              chain.doFilter(request, response);
              return;
          }
  
          Optional<VirtualUriMapping.Result> mappingBestMatch = registry.getAllDefinitions().stream()
                  .map(uriMapping -> uriMapping.mapUri(uri))
                  .filter(Optional::isPresent)
                  .map(Optional::get)
                  .max(VirtualUriMapping.Result::compareTo);
  
          if (!mappingBestMatch.isPresent()) {
              chain.doFilter(request, response);
              return;
         }
 
         VirtualUriMapping.Result result = mappingBestMatch.get();
         String targetUri = result.getToUri();
 
         if (response.isCommitted()) {
             log.warn(
                     "Response is already committed, cannot apply virtual URI {} (original URI was {})",
                     targetUri,
                     request.getRequestURI());
             chain.doFilter(request, response);
             return;
         }
 
         if (RequestDispatchUtil.dispatch(targetUri, request, response)) {
             return;
         }
 
         aggregationState.setCurrentURI(targetUri);
         chain.doFilter(request, response);
     }
 }