/**
 * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer. 2. Redistributions in
 * binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution. 3. Neither the name of SCM-Manager;
 * nor the names of its contributors may be used to endorse or promote products
 * derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * http://bitbucket.org/sdorra/scm-manager
 *
 */



package sonia.scm.cache;

//~--- non-JDK imports --------------------------------------------------------

import com.google.common.cache.CacheBuilder;
import com.google.common.collect.Sets;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import sonia.scm.Filter;

//~--- JDK imports ------------------------------------------------------------

import java.util.Set;
import java.util.concurrent.TimeUnit;

/**
 *
 * @author Sebastian Sdorra
 *
 * @param <K>
 * @param <V>
 */
public class GuavaCache<K, V> implements Cache<K, V>
{

  /**
   * the logger for GuavaCache
   */
  private static final Logger logger =
    LoggerFactory.getLogger(GuavaCache.class);

  //~--- constructors ---------------------------------------------------------

  /**
   * Constructs ...
   *
   *
   * @param configuration
   */
  public GuavaCache(NamedCacheConfiguration configuration)
  {
    this(configuration, configuration.getName());
  }

  /**
   * Constructs ...
   *
   *
   * @param configuration
   * @param name
   */
  public GuavaCache(CacheConfiguration configuration, String name)
  {
    this.name = name;

    if (configuration.getCopyStrategy() != null)
    {
      copyStrategy = configuration.getCopyStrategy();
    }

    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder();

    if (configuration.getConcurrencyLevel() != null)
    {
      builder.concurrencyLevel(configuration.getConcurrencyLevel());
    }

    if (configuration.getExpireAfterAccess() != null)
    {
      builder.expireAfterAccess(configuration.getExpireAfterAccess(),
        TimeUnit.MILLISECONDS);
    }

    if (configuration.getExpireAfterWrite() != null)
    {
      builder.expireAfterWrite(configuration.getExpireAfterWrite(),
        TimeUnit.MILLISECONDS);
    }

    if (configuration.getInitialCapacity() != null)
    {
      builder.initialCapacity(configuration.getInitialCapacity());
    }

    if (configuration.getMaximumSize() != null)
    {
      builder.maximumSize(configuration.getMaximumSize());
    }

    if (configuration.getMaximumWeight() != null)
    {
      builder.maximumWeight(configuration.getMaximumWeight());
    }

    if (isEnabled(configuration.getRecordStats()))
    {
      builder.recordStats();
    }

    if (isEnabled(configuration.getSoftValues()))
    {
      builder.softValues();
    }

    if (isEnabled(configuration.getWeakKeys()))
    {
      builder.weakKeys();
    }

    if (isEnabled(configuration.getWeakValues()))
    {
      builder.weakKeys();
    }

    cache = builder.build();

    if (logger.isTraceEnabled())
    {
      logger.trace("create new guava cache from builder: {}", builder);
    }
  }

  //~--- methods --------------------------------------------------------------

  /**
   * Method description
   *
   */
  @Override
  public void clear()
  {
    if (logger.isDebugEnabled())
    {
      logger.debug("clear cache {}", name);
    }

    cache.invalidateAll();
  }

  /**
   * Method description
   *
   *
   * @param key
   *
   * @return
   */
  @Override
  public boolean contains(K key)
  {
    return cache.getIfPresent(key) != null;
  }

  /**
   * Method description
   *
   *
   * @param key
   * @param value
   */
  @Override
  public void put(K key, V value)
  {
    cache.put(key, copyStrategy.copyOnWrite(value));
  }

  /**
   * Method description
   *
   *
   * @param key
   *
   * @return
   */
  @Override
  public boolean remove(K key)
  {
    cache.invalidate(key);

    return true;
  }

  /**
   * Method description
   *
   *
   * @param filter
   *
   * @return
   */
  @Override
  public boolean removeAll(Filter<K> filter)
  {
    Set<K> keysToRemove = Sets.newHashSet();

    for (K key : cache.asMap().keySet())
    {
      if (filter.accept(key))
      {
        keysToRemove.add(key);
      }
    }

    boolean result = false;

    if (!keysToRemove.isEmpty())
    {
      cache.invalidateAll(keysToRemove);
      result = true;
    }

    return result;
  }

  //~--- get methods ----------------------------------------------------------

  /**
   * Method description
   *
   *
   * @param key
   *
   * @return
   */
  @Override
  public V get(K key)
  {
    V value = cache.getIfPresent(key);

    if (value != null)
    {
      value = copyStrategy.copyOnRead(value);
    }

    return value;
  }

  /**
   * Method description
   *
   *
   * @param v
   *
   * @return
   */
  private boolean isEnabled(Boolean v)
  {
    return (v != null) && v;
  }

  //~--- fields ---------------------------------------------------------------

  /** Field description */
  private com.google.common.cache.Cache<K, V> cache;

  /** Field description */
  private CopyStrategy copyStrategy = CopyStrategy.NONE;

  /** Field description */
  private String name;
}