/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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.apache.commons.proxy2.cglib;
  
  import java.io.Serializable;
  import java.lang.reflect.Method;
  
  import net.sf.cglib.proxy.Callback;
  import net.sf.cglib.proxy.CallbackFilter;
  import net.sf.cglib.proxy.Dispatcher;
  import net.sf.cglib.proxy.Enhancer;
  import net.sf.cglib.proxy.MethodInterceptor;
  import net.sf.cglib.proxy.MethodProxy;
  
  import org.apache.commons.lang3.ArrayUtils;
  import org.apache.commons.lang3.ObjectUtils;
  import org.apache.commons.proxy2.Interceptor;
  import org.apache.commons.proxy2.Invocation;
  import org.apache.commons.proxy2.Invoker;
  import org.apache.commons.proxy2.ObjectProvider;
  import org.apache.commons.proxy2.ProxyUtils;
  import org.apache.commons.proxy2.impl.AbstractSubclassingProxyFactory;
  
  /**
   * Cglib-based {@link org.apache.commons.proxy2.ProxyFactory ProxyFactory} implementation.
   */
  public class CglibProxyFactory extends AbstractSubclassingProxyFactory
  {
      //******************************************************************************************************************
      // Fields
      //******************************************************************************************************************
  
      private static final CallbackFilter CALLBACKFILTER = new CglibProxyFactoryCallbackFilter();
  
      //******************************************************************************************************************
      // ProxyFactory Implementation
      //******************************************************************************************************************
  
      /**
       * {@inheritDoc}
       */
      @Override
      public <T> T createDelegatorProxy(ClassLoader classLoader, ObjectProvider<?> targetProvider,
              Class<?>... proxyClasses)
      {
          final Enhancer enhancer = new Enhancer();
          enhancer.setClassLoader(classLoader);
          enhancer.setInterfaces(toInterfaces(proxyClasses));
          enhancer.setSuperclass(getSuperclass(proxyClasses));
          enhancer.setCallbackFilter(CALLBACKFILTER);
          enhancer.setCallbacks(new Callback[] { new ObjectProviderDispatcher(targetProvider), new EqualsHandler(),
                  new HashCodeHandler() });
          @SuppressWarnings("unchecked") // type inference
          final T result = (T) enhancer.create();
          return result;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public <T> T createInterceptorProxy(ClassLoader classLoader, Object target, Interceptor interceptor,
              Class<?>... proxyClasses)
      {
          final Enhancer enhancer = new Enhancer();
          enhancer.setClassLoader(classLoader);
          enhancer.setInterfaces(toInterfaces(proxyClasses));
          enhancer.setSuperclass(getSuperclass(proxyClasses));
          enhancer.setCallbackFilter(CALLBACKFILTER);
          enhancer.setCallbacks(new Callback[] { new InterceptorBridge(target, interceptor), new EqualsHandler(),
                  new HashCodeHandler() });
          @SuppressWarnings("unchecked") // type inference
          final T result = (T) enhancer.create();
          return result;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public <T> T createInvokerProxy(ClassLoader classLoader, Invoker invoker, Class<?>... proxyClasses)
      {
          final Enhancer enhancer = new Enhancer();
          enhancer.setClassLoader(classLoader);
         enhancer.setInterfaces(toInterfaces(proxyClasses));
         enhancer.setSuperclass(getSuperclass(proxyClasses));
         enhancer.setCallbackFilter(CALLBACKFILTER);
         enhancer.setCallbacks(
                 new Callback[] { new InvokerBridge(invoker), new EqualsHandler(), new HashCodeHandler() });
         @SuppressWarnings("unchecked") // type inference
         final T result = (T) enhancer.create();
         return result;
     }
 
     //******************************************************************************************************************
     // Inner Classes
     //******************************************************************************************************************
 
     private static class CglibProxyFactoryCallbackFilter implements CallbackFilter
     {
         @Override
         public int accept(Method method)
         {
             if (ProxyUtils.isEqualsMethod(method))
             {
                 return 1;
             }
             else if (ProxyUtils.isHashCode(method))
             {
                 return 2;
             }
             else
             {
                 return 0;
             }
         }
     }
 
     private static class EqualsHandler implements MethodInterceptor, Serializable
     {
         /** Serialization version */
         private static final long serialVersionUID = 1L;
 
         @Override
         public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable
         {
             return Boolean.valueOf(o == objects[0]);
         }
     }
 
     private static class HashCodeHandler implements MethodInterceptor, Serializable
     {
         /** Serialization version */
         private static final long serialVersionUID = 1L;
 
         @Override
         public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable
         {
             return Integer.valueOf(System.identityHashCode(o));
         }
     }
 
     private static class InterceptorBridge implements MethodInterceptor, Serializable
     {
         /** Serialization version */
         private static final long serialVersionUID = 1L;
 
         private final Object target;
         private final Interceptor inner;
 
         public InterceptorBridge(Object target, Interceptor inner)
         {
             this.inner = inner;
             this.target = target;
         }
 
         @Override
         public Object intercept(Object object, Method method, Object[] args, MethodProxy methodProxy) throws Throwable
         {
             return inner.intercept(new MethodProxyInvocation(object, target, method, args, methodProxy));
         }
     }
 
     private static class InvokerBridge implements net.sf.cglib.proxy.InvocationHandler, Serializable
     {
         /** Serialization version */
         private static final long serialVersionUID = 1L;
 
         private final Invoker original;
 
         public InvokerBridge(Invoker original)
         {
             this.original = original;
         }
 
         @Override
         public Object invoke(Object object, Method method, Object[] objects) throws Throwable
         {
             return original.invoke(object, method, objects);
         }
     }
 
     private static class MethodProxyInvocation implements Invocation
     {
         private final Object proxy;
         private final Object target;
         private final Method method;
         private final Object[] args;
         private final MethodProxy methodProxy;
 
         public MethodProxyInvocation(Object proxy, Object target, Method method, Object[] args, MethodProxy methodProxy)
         {
             this.proxy = proxy;
             this.target = target;
             this.method = method;
             this.methodProxy = methodProxy;
             this.args = ObjectUtils.defaultIfNull(ArrayUtils.clone(args), ProxyUtils.EMPTY_ARGUMENTS);
         }
 
         @Override
         public Method getMethod()
         {
             return method;
         }
 
         @Override
         public Object[] getArguments()
         {
             return args;
         }
 
         @Override
         public Object proceed() throws Throwable
         {
             return methodProxy.invoke(target, args);
         }
 
         @Override
         public Object getProxy()
         {
             return proxy;
         }
     }
 
     private static class ObjectProviderDispatcher implements Dispatcher, Serializable
     {
         /** Serialization version */
         private static final long serialVersionUID = 1L;
 
         private final ObjectProvider<?> delegateProvider;
 
         public ObjectProviderDispatcher(ObjectProvider<?> delegateProvider)
         {
             this.delegateProvider = delegateProvider;
         }
 
         @Override
         public Object loadObject()
         {
             return delegateProvider.getObject();
         }
     }
 }