/*
    * ====================================================================
    * 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;
  
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.Locale;
  
  import org.apache.hc.client5.http.protocol.RedirectStrategy;
  import org.apache.hc.client5.http.utils.URIUtils;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpException;
  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.ProtocolException;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.net.URIBuilder;
  import org.apache.hc.core5.util.Args;
  
  /**
   * Default implementation of {@link RedirectStrategy}.
   *
   * @since 4.1
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  public class DefaultRedirectStrategy implements RedirectStrategy {
  
      public static final DefaultRedirectStrategy INSTANCE = new DefaultRedirectStrategy();
  
      @Override
      public boolean isRedirected(
              final HttpRequest request,
              final HttpResponse response,
              final HttpContext context) throws ProtocolException {
          Args.notNull(request, "HTTP request");
          Args.notNull(response, "HTTP response");
  
          if (!response.containsHeader(HttpHeaders.LOCATION)) {
              return false;
          }
          final int statusCode = response.getCode();
          switch (statusCode) {
              case HttpStatus.SC_MOVED_PERMANENTLY:
              case HttpStatus.SC_MOVED_TEMPORARILY:
              case HttpStatus.SC_SEE_OTHER:
              case HttpStatus.SC_TEMPORARY_REDIRECT:
              case HttpStatus.SC_PERMANENT_REDIRECT:
                  return true;
              default:
                  return false;
          }
      }
  
      @Override
      public URI getLocationURI(
              final HttpRequest request,
              final HttpResponse response,
              final HttpContext context) throws HttpException {
          Args.notNull(request, "HTTP request");
          Args.notNull(response, "HTTP response");
          Args.notNull(context, "HTTP context");
  
          //get the location header to find out where to redirect to
          final Header locationHeader = response.getFirstHeader(HttpHeaders.LOCATION);
          if (locationHeader == null) {
              throw new HttpException("Redirect location is missing");
          }
          final String location = locationHeader.getValue();
          URI uri = createLocationURI(location);
          try {
             if (!uri.isAbsolute()) {
                 // Resolve location URI
                 uri = URIUtils.resolve(request.getUri(), uri);
             }
         } catch (final URISyntaxException ex) {
             throw new ProtocolException(ex.getMessage(), ex);
         }
 
         return uri;
     }
 
     /**
      * @since 4.1
      */
     protected URI createLocationURI(final String location) throws ProtocolException {
         try {
             final URIBuilder b = new URIBuilder(new URI(location).normalize());
             final String host = b.getHost();
             if (host != null) {
                 b.setHost(host.toLowerCase(Locale.ROOT));
             }
             if (b.isPathEmpty()) {
                 b.setPathSegments("");
             }
             return b.build();
         } catch (final URISyntaxException ex) {
             throw new ProtocolException("Invalid redirect URI: " + location, ex);
         }
     }
 
 }