/*
    * 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.
   */
  package org.apache.amber.oauth2.rs;
  
  import java.io.UnsupportedEncodingException;
  import java.net.URLDecoder;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  
  import org.apache.amber.oauth2.common.exception.OAuthSystemException;
  import org.apache.amber.oauth2.common.message.types.ParameterStyle;
  import org.apache.amber.oauth2.common.utils.OAuthUtils;
  import org.apache.amber.oauth2.common.validators.OAuthValidator;
  import org.apache.amber.oauth2.rs.extractor.TokenExtractor;
  
  public abstract class ResourceServer {
  
      protected Map<ParameterStyle, Class> extractors = new HashMap<ParameterStyle, Class>();
      protected Map<ParameterStyle, Class> validators = new HashMap<ParameterStyle, Class>();
  
      public OAuthValidator instantiateValidator(ParameterStyle ps) throws OAuthSystemException {
          Class clazz = validators.get(ps);
          if (clazz == null) {
              throw new OAuthSystemException("Cannot instantiate a message validator.");
          }
          return (OAuthValidator)OAuthUtils.instantiateClass(clazz);
      }
  
      public TokenExtractor instantiateExtractor(ParameterStyle ps) throws OAuthSystemException {
          Class clazz = extractors.get(ps);
          if (clazz == null) {
              throw new OAuthSystemException("Cannot instantiate a token extractor.");
          }
          return (TokenExtractor)OAuthUtils.instantiateClass(clazz);
      }
  
      /**
       * A replacement for HttpServletRequest.getParameter() as it will mess up with HTTP POST body
       * @param request
       * @param name
       * @return
       */
      public static String[] getQueryParameterValues(HttpServletRequest request, String name) {
          String query = request.getQueryString();
          if (query == null) {
              return null;
          }
          List<String> values = new ArrayList<String>();
          String[] params = query.split("&");
          for (String param : params) {
              try {
                  param = URLDecoder.decode(param, "UTF-8");
              } catch (UnsupportedEncodingException e) {
                  // Ignore
              }
              int index = param.indexOf('=');
              String key = param;
              String value = null;
              if (index != -1) {
                  key = param.substring(0, index);
                  value = param.substring(index + 1);
              }
              if (key.equals(name)) {
                  values.add(value);
              }
          }
          return values.toArray(new String[values.size()]);
      }
  
      public static String getQueryParameterValue(HttpServletRequest request, String name) {
          String[] values = getQueryParameterValues(request, name);
          if (values == null || values.length == 0) {
              return null;
          }
          return values[0];
      }
  }