/**
 *
 * Copyright
 * 2009-2015 Jayway Products AB
 * 2016-2017 Föreningen Sambruk
 *
 * Licensed under AGPL, Version 3.0 (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.gnu.org/licenses/agpl.txt
 *
 * 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 se.streamsource.streamflow.web.domain.generic;

import java.beans.Introspector;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.qi4j.api.common.AppliesTo;
import org.qi4j.api.common.AppliesToFilter;
import org.qi4j.api.entity.EntityComposite;
import org.qi4j.api.entity.IdentityGenerator;
import org.qi4j.api.entity.association.ManyAssociation;
import org.qi4j.api.injection.scope.Service;
import org.qi4j.api.injection.scope.Structure;
import org.qi4j.api.injection.scope.This;
import org.qi4j.spi.Qi4jSPI;

import se.streamsource.streamflow.infrastructure.event.domain.DomainEvent;
import se.streamsource.streamflow.web.domain.Removable;

/**
 * Generic mixin for simple command methods that remove an entity from a collection. They have to follow this pattern:
 * boolean removeFoo(SomeType entity)
 * This will check if the entity exists in the ManyAssociation called "foos" and then call the event method
 * removedFoo(null, entity);
 * The method returns true if the entity was removed, and false if not.
 */
@AppliesTo(CommandEntityRemoveMixin.CommandEntityRemoveAppliesTo.class)
public class CommandEntityRemoveMixin
      implements InvocationHandler
{
   private static Map<Method, Method> methodMappings = new ConcurrentHashMap();
   private static Map<Method, Method> manyAssociationMappings = new ConcurrentHashMap();

   @Service
   IdentityGenerator idGen;

   @Structure
   Qi4jSPI spi;

   @This
   EntityComposite composite;

   public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable
   {
      //Method eventMethod = methodMappings.get(method);
      Method eventMethod;
      //if (eventMethod == null)
      {
         // removeFoo -> fooRemoved
         String name = method.getName().substring( "remove".length() );
         name = "removed" + name;
         Class[] parameterTypes = new Class[]{DomainEvent.class, method.getParameterTypes()[0]};
         eventMethod = composite.getClass().getMethod( name, parameterTypes );
         //methodMappings.put(method, eventMethod);
      }

      //Method manyAssociationMethod = manyAssociationMappings.get(method);
      Method manyAssociationMethod;
      //if (manyAssociationMethod == null)
      {
         // removeFoo -> foos
         String name = method.getName().substring( "remove".length() );
         name = Introspector.decapitalize( name ) + "s";
         manyAssociationMethod = composite.getClass().getMethod( name );
         //manyAssociationMappings.put(method, manyAssociationMethod);
      }

      ManyAssociation manyAssociation = (ManyAssociation) manyAssociationMethod.invoke( proxy );

      if (!manyAssociation.contains( args[0] ))
         return false; // ManyAssociation does not contain entity

      eventMethod.invoke( composite, null, args[0] );

      // Call Removable.removeEntity()
      if (args[0] instanceof Removable)
      {
         Removable removable = (Removable) args[0];
         removable.removeEntity();
      }

      return true;
   }

   public static class CommandEntityRemoveAppliesTo
         implements AppliesToFilter
   {
      public boolean appliesTo( Method method, Class<?> mixin, Class<?> compositeType, Class<?> fragmentClass )
      {
         return method.getName().startsWith( "remove" ) && method.getParameterTypes().length == 1;
      }
   }
}