/*
    * This file is part of Waarp Project (named also Waarp or GG).
    *
    *  Copyright (c) 2019, Waarp SAS, and individual contributors by the @author
    *  tags. See the COPYRIGHT.txt in the distribution for a full listing of
    * individual contributors.
    *
    *  All Waarp Project 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.
   *
   * Waarp 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
   * Waarp . If not, see <http://www.gnu.org/licenses/>.
   */
  package org.waarp.common.lru;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * Threadsafe synchronized implementation of LruCache based on LinkedHashMap.
   * Threadsafety is provided by
   * method synchronization.
   * <p>
   * This cache implementation should be used with low number of threads.
   *
   * @author Damian Momot
   */
  public class SynchronizedLruCache<K, V> extends AbstractLruCache<K, V> {
    private static final int DEFAULT_INITIAL_CAPACITY = 16;
  
    private static final float DEFAULT_LOAD_FACTOR = 0.75f;
  
    private final CapacityLruLinkedHashMap<K, InterfaceLruCacheEntry<V>> cacheMap;
  
    /**
     * Creates new SynchronizedLruCache
     *
     * @param capacity max cache capacity
     * @param ttl time to live in milliseconds
     * @param initialCapacity initial cache capacity
     * @param loadFactor
     */
    public SynchronizedLruCache(final int capacity, final long ttl,
                                final int initialCapacity,
                                final float loadFactor) {
      super(ttl);
      cacheMap =
          new CapacityLruLinkedHashMap<K, InterfaceLruCacheEntry<V>>(capacity,
                                                                     initialCapacity,
                                                                     loadFactor);
    }
  
    /**
     * Creates new SynchronizedLruCache with DEFAULT_LOAD_FACTOR
     *
     * @param capacity max cache capacity
     * @param ttl time to live in milliseconds
     * @param initialCapacity initial cache capacity
     */
    public SynchronizedLruCache(final int capacity, final long ttl,
                                final int initialCapacity) {
      this(capacity, ttl, initialCapacity, DEFAULT_LOAD_FACTOR);
    }
  
    /**
     * Creates new SynchronizedLruCache with DEFAULT_LOAD_FACTOR and
     * DEFAULT_INITIAL_CAPACITY
     *
     * @param capacity max cache capacity
     * @param ttl time to live in milliseconds
     */
    public SynchronizedLruCache(final int capacity, final long ttl) {
      this(capacity, ttl, DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR);
    }
  
    @Override
    public synchronized void clear() {
      cacheMap.clear();
    }
  
    @Override
    public synchronized V get(final K key) {
      return super.get(key);
    }
  
    @Override
    public final int getCapacity() {
      return cacheMap.getCapacity();
    }
  
    @Override
   protected final InterfaceLruCacheEntry<V> getEntry(final K key) {
     return cacheMap.get(key);
   }
 
   @Override
   public synchronized int size() {
     return cacheMap.size();
   }
 
   @Override
   public synchronized void put(final K key, final V value, final long ttl) {
     super.put(key, value, ttl);
   }
 
   @Override
   protected final void putEntry(final K key,
                                 final InterfaceLruCacheEntry<V> entry) {
     cacheMap.put(key, entry);
   }
 
   @Override
   public synchronized V remove(final K key) {
     final InterfaceLruCacheEntry<V> cv = cacheMap.remove(key);
     if (cv != null) {
       return cv.getValue();
     }
     return null;
   }
 
   @Override
   public final Collection<V> values() {
     final Collection<InterfaceLruCacheEntry<V>> cacheEntry = cacheMap.values();
     final List<V> list = new ArrayList<V>(cacheEntry.size());
     for (final InterfaceLruCacheEntry<V> entry : cacheEntry) {
       list.add(entry.getValue());
     }
     return list;
   }
 
   @Override
   public synchronized int forceClearOldest() {
     final long timeRef = System.currentTimeMillis();
     final Collection<InterfaceLruCacheEntry<V>> collection = cacheMap.values();
     final Iterator<InterfaceLruCacheEntry<V>> iterator = collection.iterator();
     int nb = 0;
     while (iterator.hasNext()) {
       final InterfaceLruCacheEntry<V> v = iterator.next();
       if (!v.isStillValid(timeRef)) {
         iterator.remove();
         nb++;
       }
     }
     return nb;
   }
 
 }