/* 
    * Licensed 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.esigate.extension;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.Properties;
  
  import org.esigate.ConfigurationException;
  import org.esigate.Driver;
  import org.esigate.util.Parameter;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Factory for all ESIGate extension classes (authenticator, cookie store).
   * 
   * @author Nicolas Richeton
   * @author Francois-Xavier Bonnet
   * 
   */
  public final class ExtensionFactory {
      private static final Logger LOG = LoggerFactory.getLogger(ExtensionFactory.class);
  
      private ExtensionFactory() {
  
      }
  
      /**
       * Get an extension as configured in properties.
       * 
       * @param properties
       *            properties
       * @param parameter
       *            the class name parameter
       * @param d
       *            driver
       * 
       * @param <T>
       *            class which extends Extension class which extends Extension
       * @return instance of {@link Extension} or null.
       */
      public static <T extends Extension> T getExtension(Properties properties, Parameter<String> parameter, Driver d) {
          T result;
          String className = parameter.getValue(properties);
          if (className == null) {
              return null;
          }
          try {
              if (LOG.isDebugEnabled()) {
                  LOG.debug("Creating  extension " + className);
              }
              result = (T) Class.forName(className).newInstance();
              result.init(d, properties);
          } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
              throw new ConfigurationException(e);
          }
          return result;
      }
  
      /**
       * Get an extension list, as defined in the properties (comma-separated list).
       * 
       * @param properties
       * @param parameter
       * @param d
       * @return the extension list
       */
      public static <T extends Extension> List<T> getExtensions(Properties properties,
              Parameter<Collection<String>> parameter, Driver d) {
          Collection<String> className = parameter.getValue(properties);
          List<T> finalResult = new ArrayList<>();
          for (String cName : className) {
              try {
                  T result;
  
                  if (LOG.isDebugEnabled()) {
                      LOG.debug("Creating  extension " + className);
                  }
                  result = (T) Class.forName(cName).newInstance();
                  result.init(d, properties);
                  finalResult.add(result);
              } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
                  throw new ConfigurationException(e);
              }
         }
         return finalResult;
     }
 
 }