/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  package org.mycore.oai;
  
  import java.time.Instant;
  import java.util.Collection;
  import java.util.Map;
  import java.util.stream.Collectors;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.jdom2.Element;
  import org.mycore.common.config.MCRConfiguration2;
  import org.mycore.common.xml.MCRURIResolver;
  import org.mycore.oai.pmh.DateUtils;
  import org.mycore.oai.pmh.Description;
  import org.mycore.oai.pmh.FriendsDescription;
  import org.mycore.oai.pmh.Granularity;
  import org.mycore.oai.pmh.Identify;
  import org.mycore.oai.pmh.OAIIdentifierDescription;
  import org.mycore.oai.pmh.SimpleIdentify;
  
  /**
   * Simple MyCoRe implementation of a OAI-PMH {@link Identify} class. Uses the {@link MCRConfiguration2} to retrieve
   * all important settings. Earliest date stamp is calculated with the 'restriction' query and sort by 'created'.
   * Also adds custom description elements from URIs configured by MCR.OAIDataProvider.OAI.DescriptionURI
   *
   * @author Matthias Eichner
   * @author Frank L\u00fctzenkirchen
   */
  public class MCROAIIdentify extends SimpleIdentify {
  
      protected static final Logger LOGGER = LogManager.getLogger(MCROAIIdentify.class);
  
      protected String configPrefix;
  
      public MCROAIIdentify(String baseURL, String configPrefix) {
          this.configPrefix = configPrefix;
  
          this.setBaseURL(baseURL);
          this.setRepositoryName(
              MCRConfiguration2.getString(configPrefix + "RepositoryName").orElse("Undefined repository name"));
          String deletedRecordPolicy = MCRConfiguration2.getString(configPrefix + "DeletedRecord")
              .orElse(DeletedRecordPolicy.Transient.name());
          this.setDeletedRecordPolicy(DeletedRecordPolicy.get(deletedRecordPolicy));
          String granularity = MCRConfiguration2.getString(configPrefix + "Granularity")
              .orElse(Granularity.YYYY_MM_DD.name());
          this.setGranularity(Granularity.valueOf(granularity));
          String adminMail = MCRConfiguration2.getString(configPrefix + "AdminEmail")
              .orElseGet(() -> MCRConfiguration2.getStringOrThrow("MCR.Mail.Sender"));
  
          this.setEarliestDatestamp(calculateEarliestTimestamp());
          this.getAdminEmailList().add(adminMail);
          this.getDescriptionList().add(getIdentifierDescription());
          if (!getFriendsDescription().getFriendsList().isEmpty()) {
              this.getDescriptionList().add(getFriendsDescription());
          }
  
          addCustomDescriptions();
      }
  
      private void addCustomDescriptions() {
          for (final String descriptionURI : getDescriptionURIs()) {
              this.getDescriptionList().add(new CustomDescription(descriptionURI));
          }
      }
  
      /**
       * Calculates the earliest date stamp.
       *
       * @return the create date of the oldest document within the repository
       */
      protected Instant calculateEarliestTimestamp() {
          MCROAISearcher searcher = MCROAISearchManager.getSearcher(this, null, 1, null, null);
          return searcher.getEarliestTimestamp().orElse(DateUtils
              .parse(MCRConfiguration2.getString(this.configPrefix + "EarliestDatestamp").orElse("1970-01-01")));
      }
  
      public String getConfigPrefix() {
          return configPrefix;
      }
  
      private Collection<String> getDescriptionURIs() {
          String descriptionConfig = getConfigPrefix() + "DescriptionURI";
         return MCRConfiguration2.getPropertiesMap()
             .entrySet()
             .stream()
             .filter(p -> p.getKey().startsWith(descriptionConfig))
             .map(Map.Entry::getValue)
             .collect(Collectors.toSet());
     }
 
     public FriendsDescription getFriendsDescription() {
         FriendsDescription desc = new FriendsDescription();
         MCRConfiguration2.getPropertiesMap()
             .entrySet()
             .stream()
             .filter(p -> p.getKey().startsWith(this.configPrefix + "Friends."))
             .map(Map.Entry::getValue)
             .forEach(desc.getFriendsList()::add);
         return desc;
     }
 
     public OAIIdentifierDescription getIdentifierDescription() {
         String reposId = MCRConfiguration2.getStringOrThrow(this.configPrefix + "RepositoryIdentifier");
         String sampleId = MCRConfiguration2.getStringOrThrow(this.configPrefix + "RecordSampleID");
         return new OAIIdentifierDescription(reposId, sampleId);
     }
 
     class CustomDescription implements Description {
 
         private Element description;
 
         CustomDescription(String descriptionURI) {
             description = MCRURIResolver.instance().resolve(descriptionURI);
         }
 
         @Override
         public void fromXML(Element description) {
             this.description = description;
         }
 
         @Override
         public Element toXML() {
             return description.getChildren().get(0).clone();
         }
     }
 
 }