/*
    * Grapht, an open source dependency injector.
    * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt)
    * Copyright 2010-2014 Regents of the University of Minnesota
    *
    * This program 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 program 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
   * this program; if not, write to the Free Software Foundation, Inc., 51
   * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   */
  package org.grouplens.grapht.reflect.internal;
  
  import org.grouplens.grapht.*;
  import org.grouplens.grapht.reflect.*;
  import org.grouplens.grapht.util.Preconditions;
  import org.grouplens.grapht.util.Types;
  
  import javax.inject.Provider;
  import javax.inject.Singleton;
  import java.io.Serializable;
  import java.lang.reflect.Type;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  
  /**
   * Satisfaction implementation wrapping an existing Provider instance. It has no
   * dependencies and it always returns the same Provider when
   * {@link Satisfaction#makeInstantiator(Map, LifecycleManager)} is invoked.
   * 
   * @author <a href="http://grouplens.org">GroupLens Research</a>
   */
  public class ProviderInstanceSatisfaction implements Satisfaction, Serializable {
      private static final long serialVersionUID = 1L;
      @SuppressWarnings("squid:S1948") // serializable warning; satisfaction is serializable iff provider is
      private final Provider<?> provider;
  
      /**
       * Create a new satisfaction that wraps the given Provider instance.
       * 
       * @param provider The provider
       * @throws NullPointerException if provider is null
       */
      public ProviderInstanceSatisfaction(Provider<?> provider) {
          Preconditions.notNull("provider", provider);
          this.provider = provider;
      }
      
      @Override
      public CachePolicy getDefaultCachePolicy() {
          return (getErasedType().getAnnotation(Singleton.class) != null ? CachePolicy.MEMOIZE : CachePolicy.NO_PREFERENCE);
      }
      
      /**
       * @return The provider instance returned by {@link Satisfaction#makeInstantiator(Map, LifecycleManager)}
       */
      public Provider<?> getProvider() {
          return provider;
      }
      
      @Override
      public List<Desire> getDependencies() {
          return Collections.emptyList();
      }
  
      @Override
      public Type getType() {
          return Types.getProvidedType(provider);
      }
  
      @Override
      public Class<?> getErasedType() {
          return Types.erase(getType());
      }
  
      @Override
      public boolean hasInstance() {
          return false;
      }
  
      @Override
      public <T> T visit(SatisfactionVisitor<T> visitor) {
          return visitor.visitProviderInstance(provider);
      }
  
      @Override
      public Instantiator makeInstantiator(Map<Desire,Instantiator> dependencies,
                                           LifecycleManager lm) {
          return Instantiators.ofProvider(provider);
     }
     
     @Override
     public boolean equals(Object o) {
         return (o instanceof ProviderInstanceSatisfaction)
                && ((ProviderInstanceSatisfaction) o).provider.equals(provider);
     }
     
     @Override
     public int hashCode() {
         return provider.hashCode();
     }
     
     @Override
     public String toString() {
         return "ProviderInstance(" + provider + ")";
     }
 }