/**
 *
 * 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.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.injection.scope.State;
import org.qi4j.api.injection.scope.This;
import org.qi4j.api.property.StateHolder;

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

/**
 * Generic mixin for simple command methods that update a property.
 * <p/>
 * It can implement methods that follow these rules:
 * * The method must have one parameter
 * * The name must start with "change"
 * <p/>
 * Example: void changeFoo(String newValue) -> invoke event method "changedFoo(newValue);"
 */
@AppliesTo(CommandPropertyChangeMixin.CommandPropertyChangeAppliesTo.class)
public class CommandPropertyChangeMixin
      implements InvocationHandler
{
   private static Map<Method, Method> methodMappings = new ConcurrentHashMap<Method, Method>();

   @State
   StateHolder state;

   @This
   EntityComposite composite;

   public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable
   {
      Method eventMethod = methodMappings.get( method );

      if (eventMethod == null)
      {
         // changeFoo -> fooChanged
         String name = method.getName().substring( "change".length() );
         name = "changed" + name;
         Class[] parameterTypes = new Class[]{DomainEvent.class, method.getParameterTypes()[0]};
         eventMethod = composite.getClass().getInterfaces()[0].getMethod( name, parameterTypes );
         methodMappings.put( method, eventMethod );
      }

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

      return null;
   }

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