/*
    * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
    *
    * This library is free software; you can redistribute it and/or
    * modify it under the terms of the GNU Lesser General Public
    * License as published by the Free Software Foundation; either
    * version 2.1 of the License, or (at your option) any later version.
    *
    * This library 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 Lesser General Public
   * License along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
   *
   * Additionally licensed with:
   *
   * Licensed 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.spf4j.reflect;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  import java.lang.reflect.Type;
  import java.util.Set;
  import java.util.function.Function;
  import javax.annotation.concurrent.GuardedBy;
  import javax.annotation.concurrent.ThreadSafe;
  import org.spf4j.concurrent.UnboundedLoadingCache;
  
  /**
   * @author Zoltan Farkas
   */
  @ThreadSafe
  public final class CachingTypeMapWrapper<H> implements TypeMap<H> {
  
    private final LoadingCache<Type, Set<H>> cache;
  
    @GuardedBy("syncObj")
    private final TypeMap<H> wrapped;
  
    private final Object syncObj;
  
    @SuppressFBWarnings("EI_EXPOSE_REP2")
    public CachingTypeMapWrapper(final CacheBuilder<Type, Set<H>> cacheBuilder, final TypeMap wrapped) {
      this.syncObj = new Object();
      this.wrapped = wrapped;
      cache = cacheBuilder.build(new TypeMapedObjLoader());
    }
  
    @SuppressFBWarnings("EI_EXPOSE_REP2")
    public CachingTypeMapWrapper(final TypeMap wrapped) {
      this.syncObj = new Object();
      this.wrapped = wrapped;
      cache = new UnboundedLoadingCache<>(16, new TypeMapedObjLoader());
    }
  
  
    @Override
    public Set<H> getAll(final Type t) {
      return cache.getUnchecked(t);
    }
  
    @Override
    public boolean putIfNotPresent(final Type type, final H appender) {
      synchronized (syncObj) {
        return wrapped.putIfNotPresent(type, appender);
      }
    }
  
    @Override
    public boolean remove(final Type type) {
      boolean remove;
      synchronized (syncObj) {
        remove = wrapped.remove(type);
      }
      if (remove) {
        cache.invalidateAll(); // a bit lazy
        return true;
      } else {
        return false;
      }
    }
  
    @Override
   public H getExact(final Type t) {
     synchronized (wrapped) {
       return wrapped.getExact(t);
     }
   }
 
   public void replace(final Type t, final Function<H, H> f) {
     synchronized (wrapped) {
       H exact = wrapped.getExact(t);
       if (exact != null && !wrapped.remove(t)) {
         throw new IllegalStateException("Illegal Stat, type = " + t + " wrapped =  " + wrapped);
       }
       wrapped.safePut(t, f.apply(exact));
      }
     cache.invalidateAll(); // a bit lazy :-)
   }
 
   public void clearCache() {
     cache.invalidateAll();
   }
 
   private final class TypeMapedObjLoader extends CacheLoader<Type, Set<H>> {
 
     @Override
     public Set<H> load(final Type key) throws Exception {
       synchronized (wrapped) {
         return wrapped.getAll(key);
       }
     }
   }
 
   @Override
   public String toString() {
     String wts;
     synchronized (wrapped) {
       wts = wrapped.toString();
     }
     return "CachingTypeMapWrapper{" + "cache=" + cache + ", wrapped=" + wts + '}';
   }
 
 
 }