/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This 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 software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.aop.proxy;

import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtField;
import javassist.CtMethod;
import javassist.CtNewMethod;
import javassist.Modifier;
import org.jboss.aop.AspectManager;
import org.jboss.aop.ClassInstanceAdvisor;
import org.jboss.aop.InstanceAdvisor;
import org.jboss.aop.util.JavassistMethodHashing;
import org.jboss.util.collection.WeakValueHashMap;
import org.jboss.util.id.GUID;

import java.lang.reflect.Field;
import java.util.HashSet;
import java.util.Map;

/**
 * Comment
 *
 * @author <a href="mailto:bill@jboss.org">Bill Burke</a>
 * @version $Revision$
 */
public class ProxyFactory
{
   private static long counter = 0;
   private static WeakValueHashMap proxyCache = new WeakValueHashMap();

   public static Proxy createInterfaceProxy(ClassLoader loader, Class[] interfaces, ProxyMixin[] mixins, InstanceAdvisor advisor) throws Exception
   {
      Class clazz = createProxyClass(loader, mixins, interfaces);

      Proxy instance = (Proxy) clazz.newInstance();
      instance.instanceAdvisor = advisor;
      instance.mixins = mixins;
      instance.interfaces = interfaces;
      instance.guid = new GUID();

      synchronized (proxyCache)
      {
         proxyCache.put(instance.guid, clazz);
      }

      return instance;
   }

   public static Class getProxyClass(GUID guid)
   {
      synchronized (proxyCache)
      {
         return (Class) proxyCache.get(guid);
      }
   }

   public static Proxy createInterfaceProxy(GUID guid, ClassLoader loader, Class[] interfaces) throws Exception
   {
      return createInterfaceProxy(guid, loader, interfaces, null, new ClassInstanceAdvisor());
   }

   public static Proxy createInterfaceProxy(GUID guid, ClassLoader loader, Class[] interfaces, ProxyMixin[] mixins, InstanceAdvisor advisor) throws Exception
   {
      Class clazz = getProxyClass(guid);
      boolean wasFound = true;
      if (clazz == null)
      {
         wasFound = false;
         clazz = createProxyClass(loader, mixins, interfaces);
      }

      Proxy instance = (Proxy) clazz.newInstance();
      instance.instanceAdvisor = advisor;
      instance.mixins = mixins;
      instance.interfaces = interfaces;
      instance.guid = guid;

      if (!wasFound)
      {
         synchronized (proxyCache)
         {
            proxyCache.put(guid, clazz);
         }
      }

      return instance;
   }

   private static Class createProxyClass(ClassLoader loader, ProxyMixin[] mixins, Class[] interfaces)
   throws Exception
   {
      CtClass proxy = createProxyCtClass(loader, mixins, interfaces);

      Class clazz = proxy.toClass(loader);
      Map methodmap = ClassProxyFactory.getMethodMap(clazz);
      Field field = clazz.getDeclaredField("methodMap");
      field.setAccessible(true);
      field.set(null, methodmap);
      return clazz;
   }

   public static GUID generateProxyClass(ClassLoader loader, ProxyMixin[] mixins, Class[] interfaces) throws Exception
   {
      Class clazz = createProxyClass(loader, mixins, interfaces);
      GUID guid = new GUID();

      synchronized (proxyCache)
      {
         proxyCache.put(guid, clazz);
      }

      return guid;
   }

   private static CtClass createProxyCtClass(ClassLoader loader, ProxyMixin[] mixins, Class[] interfaces)
   throws Exception
   {
      ClassPool pool = AspectManager.instance().findClassPool(loader);
      if (pool == null) throw new NullPointerException("Could not find ClassPool");

      String classname = "AOPProxy$" + counter++;

      CtClass base = pool.get("org.jboss.aop.proxy.Proxy");
      CtClass proxy = pool.makeClass(classname, base);
      proxy.addInterface(pool.get("org.jboss.aop.instrument.Untransformable"));
      CtClass map = pool.get("java.util.Map");
      CtField methodMap = new CtField(map, "methodMap", proxy);
      methodMap.setModifiers(Modifier.PRIVATE | Modifier.STATIC);
      proxy.addField(methodMap);
      CtMethod getMethodMap = CtNewMethod.getter("getMethodMap", methodMap);
      getMethodMap.setModifiers(Modifier.PUBLIC);
      proxy.addMethod(getMethodMap);

      HashSet addedInterfaces = new HashSet();
      HashSet addedMethods = new HashSet();
      if (mixins != null)
      {
         for (int i = 0; i < mixins.length; i++)
         {
            HashSet mixinMethods = new HashSet();
            Class[] mixinf = mixins[i].getInterfaces();
            ClassPool mixPool = AspectManager.instance().findClassPool(mixins[i].getMixin().getClass().getClassLoader());
            CtClass mixClass = mixPool.get(mixins[i].getMixin().getClass().getName());
            for (int j = 0; j < mixinf.length; j++)
            {
               if (addedInterfaces.contains(mixinf[j].getName())) throw new Exception("2 mixins are implementing the same interfaces");
               ClassPool mixIntfPool = AspectManager.instance().findClassPool(mixinf[j].getClassLoader());
               CtClass intfClass = mixIntfPool.get(mixinf[j].getName());
               CtMethod[] methods = intfClass.getMethods();
               for (int m = 0; m < methods.length; m++)
               {
                  if (methods[m].getDeclaringClass().getName().equals("java.lang.Object")) continue;
                  Long hash = new Long(JavassistMethodHashing.methodHash(methods[m]));
                  if (mixinMethods.contains(hash)) continue;
                  if (addedMethods.contains(hash)) throw new Exception("More than one mixin has same method");
                  mixinMethods.add(hash);
                  addedMethods.add(hash);
                  String returnStr = (methods[m].getReturnType().equals(CtClass.voidType)) ? "" : "return ";
                  String code = "{" +
                  "   " + mixClass.getName() + " mixin = (" + mixClass.getName() + ")mixins[" + i + "].getMixin();" +
                  "   " + returnStr + " mixin." + methods[m].getName() + "($$);" +
                  "}";
                  CtMethod newMethod = CtNewMethod.make(methods[m].getReturnType(), methods[m].getName(), methods[m].getParameterTypes(), methods[m].getExceptionTypes(), code, proxy);
                  newMethod.setModifiers(Modifier.PUBLIC);
                  proxy.addMethod(newMethod);
               }

               proxy.addInterface(intfClass);
               addedInterfaces.add(intfClass.getName());
            }
         }
      }

      for (int i = 0; i < interfaces.length; i++)
      {
         if (addedInterfaces.contains(interfaces[i].getName())) continue;
         ClassPool mixPool = AspectManager.instance().findClassPool(interfaces[i].getClassLoader());
         CtClass intfClass = mixPool.get(interfaces[i].getName());
         CtMethod[] methods = intfClass.getMethods();
         for (int m = 0; m < methods.length; m++)
         {
            if (methods[m].getDeclaringClass().getName().equals("java.lang.Object")) continue;
            Long hash = new Long(JavassistMethodHashing.methodHash(methods[m]));
            if (addedMethods.contains(hash)) continue;
            addedMethods.add(hash);
            String aopReturnStr = (methods[m].getReturnType().equals(CtClass.voidType)) ? "" : "return ($r)";
            String args = "null";
            if (methods[m].getParameterTypes().length > 0) args = "$args";
            String code = "{   " +
            "    org.jboss.aop.advice.Interceptor[] aspects = instanceAdvisor.getInterceptors(); " +
            "    org.jboss.aop.MethodInfo mi = new org.jboss.aop.MethodInfo(); " +
            "    mi.hash = " + hash.longValue() + "L;" +
            "    org.jboss.aop.proxy.ProxyMethodInvocation invocation = new org.jboss.aop.proxy.ProxyMethodInvocation(this, mi, aspects); " +
            "    invocation.setInstanceResolver(instanceAdvisor.getMetaData()); " +
            "    invocation.setArguments(" + args + "); " +
            "    " + aopReturnStr + " invocation.invokeNext(); " +
            "}";
            CtMethod newMethod = CtNewMethod.make(methods[m].getReturnType(), methods[m].getName(), methods[m].getParameterTypes(), methods[m].getExceptionTypes(), code, proxy);
            newMethod.setModifiers(Modifier.PUBLIC);
            proxy.addMethod(newMethod);
         }
         proxy.addInterface(intfClass);
      }
      return proxy;
   }
}
