/*
    * 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.common.processing;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.Stream;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  /**
   * Base implementation of a processable collection.
   * 
   * @author Matthias Eichner
   */
  public class MCRProcessableDefaultCollection implements MCRProcessableCollection {
  
      private static Logger LOGGER = LogManager.getLogger();
  
      private String name;
  
      private final List<MCRProcessable> processables;
  
      private Map<String, Object> properties;
  
      private final List<MCRProcessableCollectionListener> listenerList;
  
      /**
       * Creates a new collection with the given a human readable name.
       * 
       * @param name name of this collection
       */
      public MCRProcessableDefaultCollection(String name) {
          this.name = name;
          this.processables = Collections.synchronizedList(new ArrayList<>());
          this.properties = new HashMap<>();
          this.listenerList = Collections.synchronizedList(new ArrayList<>());
      }
  
      /**
       * Returns the human readable name of this collection.
       */
      public String getName() {
          return name;
      }
  
      @Override
      public void add(MCRProcessable processable) {
          this.processables.add(processable);
          fireAdded(processable);
      }
  
      @Override
      public void remove(MCRProcessable processable) {
          this.processables.remove(processable);
          fireRemoved(processable);
      }
  
      @Override
      public Stream<MCRProcessable> stream() {
          List<MCRProcessable> snapshot;
          synchronized (this.processables) {
              snapshot = new ArrayList<>(this.processables);
          }
          return snapshot.stream();
      }
  
      @Override
      public boolean isEmpty() {
          return this.processables.isEmpty();
      }
  
      @Override
      public Map<String, Object> getProperties() {
          return this.properties;
      }
  
      public void setProperty(String propertyName, Object propertyValue) {
          Object oldValue = this.properties.get(propertyName);
         if (oldValue == null && propertyValue == null) {
             return;
         }
         if (propertyValue == null) {
             this.properties.remove(propertyName);
             firePropertyChanged(propertyName, oldValue, null);
             return;
         }
         if (propertyValue.equals(oldValue)) {
             return;
         }
         this.properties.put(propertyName, propertyValue);
         firePropertyChanged(propertyName, oldValue, propertyValue);
     }
 
     @Override
     public void addListener(MCRProcessableCollectionListener listener) {
         this.listenerList.add(listener);
     }
 
     @Override
     public void removeListener(MCRProcessableCollectionListener listener) {
         this.listenerList.remove(listener);
     }
 
     protected void fireAdded(MCRProcessable processable) {
         List<MCRProcessableCollectionListener> listeners = listenersSnapshot();
         listeners.forEach(listener -> {
             try {
                 listener.onAdd(this, processable);
             } catch (Exception exc) {
                 LOGGER.error("Unable to inform collection listener due internal error", exc);
             }
         });
     }
 
     protected void fireRemoved(MCRProcessable processable) {
         List<MCRProcessableCollectionListener> listeners = listenersSnapshot();
         listeners.forEach(listener -> {
             try {
                 listener.onRemove(this, processable);
             } catch (Exception exc) {
                 LOGGER.error("Unable to inform collection listener due internal error", exc);
             }
         });
     }
 
     protected void firePropertyChanged(String propertyName, Object oldValue, Object newValue) {
         List<MCRProcessableCollectionListener> listeners = listenersSnapshot();
         listeners.forEach(listener -> {
             try {
                 listener.onPropertyChange(this, propertyName, oldValue, newValue);
             } catch (Exception exc) {
                 LOGGER.error("Unable to inform collection listener due internal error", exc);
             }
         });
     }
 
     private List<MCRProcessableCollectionListener> listenersSnapshot() {
         synchronized (this.listenerList) {
             return new ArrayList<>(this.listenerList);
         }
     }
 
 }