/*
    * 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.any23.extractor;
  
  import org.apache.any23.configuration.DefaultConfiguration;
  import org.apache.any23.extractor.csv.CSVExtractor;
  import org.apache.any23.extractor.html.AdrExtractor;
  import org.apache.any23.extractor.html.GeoExtractor;
  import org.apache.any23.extractor.html.HCalendarExtractor;
  import org.apache.any23.extractor.html.HCardExtractor;
  import org.apache.any23.extractor.html.HListingExtractor;
  import org.apache.any23.extractor.html.HRecipeExtractor;
  import org.apache.any23.extractor.html.HResumeExtractor;
  import org.apache.any23.extractor.html.HReviewExtractor;
  import org.apache.any23.extractor.html.HTMLMetaExtractor;
  import org.apache.any23.extractor.html.HeadLinkExtractor;
  import org.apache.any23.extractor.html.ICBMExtractor;
  import org.apache.any23.extractor.html.LicenseExtractor;
  import org.apache.any23.extractor.html.SpeciesExtractor;
  import org.apache.any23.extractor.html.TitleExtractor;
  import org.apache.any23.extractor.html.TurtleHTMLExtractor;
  import org.apache.any23.extractor.html.XFNExtractor;
  import org.apache.any23.extractor.microdata.MicrodataExtractor;
  import org.apache.any23.extractor.rdf.NQuadsExtractor;
  import org.apache.any23.extractor.rdf.NTriplesExtractor;
  import org.apache.any23.extractor.rdf.RDFXMLExtractor;
  import org.apache.any23.extractor.rdf.TriXExtractor;
  import org.apache.any23.extractor.rdf.TurtleExtractor;
  import org.apache.any23.extractor.rdfa.RDFa11Extractor;
  import org.apache.any23.extractor.rdfa.RDFaExtractor;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   *  Singleton class acting as a register for all the various
   *  {@link Extractor}.
   */
  public class ExtractorRegistryImpl implements ExtractorRegistry {
  
      /**
       * The instance.
       */
      private static ExtractorRegistry instance = null;
  
      /**
       * maps containing the related {@link ExtractorFactory} for each
       * registered {@link Extractor}.
       */
      private Map<String, ExtractorFactory<?>> factories = new HashMap<String, ExtractorFactory<?>>();
  
      /**
       * @return returns the {@link ExtractorRegistry} instance.
       */
      public static ExtractorRegistry getInstance() {
          // Thread-safe
          synchronized (ExtractorRegistry.class) {
              final DefaultConfiguration conf = DefaultConfiguration.singleton();
              if (instance == null) {
                  instance = new ExtractorRegistryImpl();
                  // FIXME: Remove these hardcoded links to the extractor factories by turning them into SPI interfaces
                  instance.register(RDFXMLExtractor.factory);
                  instance.register(TurtleExtractor.factory);
                  instance.register(NTriplesExtractor.factory);
                  instance.register(NQuadsExtractor.factory);
                  instance.register(TriXExtractor.factory);
                  if(conf.getFlagProperty("any23.extraction.rdfa.programmatic")) {
                      instance.register(RDFa11Extractor.factory);
                  } else {
                      instance.register(RDFaExtractor.factory);
                  }
                  instance.register(HeadLinkExtractor.factory);
                  instance.register(LicenseExtractor.factory);
                  instance.register(TitleExtractor.factory);
                  instance.register(XFNExtractor.factory);
                  instance.register(ICBMExtractor.factory);
                  instance.register(AdrExtractor.factory);
                  instance.register(GeoExtractor.factory);
                  instance.register(HCalendarExtractor.factory);
                  instance.register(HCardExtractor.factory);
                  instance.register(HListingExtractor.factory);
                 instance.register(HResumeExtractor.factory);
                 instance.register(HReviewExtractor.factory);
                 instance.register(HRecipeExtractor.factory);
                 instance.register(SpeciesExtractor.factory);
                 instance.register(TurtleHTMLExtractor.factory);
                 instance.register(MicrodataExtractor.factory);
                 instance.register(CSVExtractor.factory);
                 if(conf.getFlagProperty("any23.extraction.head.meta")) {
                     instance.register(HTMLMetaExtractor.factory);
                 }
             }
         }
         return instance;
     }
 
     /**
      * Registers an {@link ExtractorFactory}.
      *
      * @param factory
      * @throws IllegalArgumentException if trying to register a {@link ExtractorFactory}
      *         with a that already exists in the registry.
      */
     public void register(ExtractorFactory<?> factory) {
         if (factories.containsKey(factory.getExtractorName())) {
             throw new IllegalArgumentException(String.format("Extractor name clash: %s",
                     factory.getExtractorName()));
         }
         factories.put(factory.getExtractorName(), factory);
     }
 
     /**
      *
      * Retrieves a {@link ExtractorFactory} given its name
      *
      * @param name of the desired factory
      * @return the {@link ExtractorFactory} associated to the provided name
      * @throws IllegalArgumentException if there is not a
      * {@link ExtractorFactory} associated to the provided name.
      */
     public ExtractorFactory<?> getFactory(String name) {
         if (!factories.containsKey(name)) {
             throw new IllegalArgumentException("Unregistered extractor name: " + name);
         }
         return factories.get(name);
     }
 
     /**
      * @return an {@link ExtractorGroup} with all the registered
      * {@link Extractor}.
      */
     public ExtractorGroup getExtractorGroup() {
         return getExtractorGroup(getAllNames());
     }
 
     /**
      * Returns an {@link ExtractorGroup} containing the
      * {@link ExtractorFactory} mathing the names provided as input.
      * @param names a {@link java.util.List} containing the names of the desired {@link ExtractorFactory}.
      * @return the extraction group.
      */
     public ExtractorGroup getExtractorGroup(List<String> names) {
         List<ExtractorFactory<?>> members = new ArrayList<ExtractorFactory<?>>(names.size());
         for (String name : names) {
             members.add(getFactory(name));
         }
         return new ExtractorGroup(members);
     }
 
     /**
      * 
      * @param name of the {@link ExtractorFactory}
      * @return <code>true</code> if is there a {@link ExtractorFactory}
      * associated to the provided name.
      */
     public boolean isRegisteredName(String name) {
         return factories.containsKey(name);
     }
 
     /**
      * Returns the names of all registered extractors, sorted alphabetically.
      */
     public List<String> getAllNames() {
         List<String> result = new ArrayList<String>(factories.keySet());
         Collections.sort(result);
         return result;
     }
 
 }