/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services 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.
 *
 *   Granite Data Services 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 library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.hibernate.jmf;

import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import javax.persistence.Entity;
import javax.persistence.MappedSuperclass;

import org.granite.logging.Logger;
import org.granite.messaging.jmf.ExtendedObjectInput;
import org.granite.messaging.jmf.ExtendedObjectOutput;
import org.granite.messaging.jmf.codec.ExtendedObjectCodec;
import org.granite.messaging.reflect.Property;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;

/**
 * @author Franck WOLFF
 */
public class EntityCodec implements ExtendedObjectCodec {

        private static final Logger log = Logger.getLogger(EntityCodec.class);
        
        private final ConcurrentMap<Class<?>, SerializableProxyAdapter> serializableProxyAdapters = new ConcurrentHashMap<Class<?>, SerializableProxyAdapter>();
                
        static class SerializableProxyAdapter {
                
                private final Object serializableProxy;
                private final Field idField;
                private final Method readResolveMethod;
                
                public SerializableProxyAdapter(HibernateProxy proxy) throws NoSuchMethodException, SecurityException, NoSuchFieldException {
                        this.serializableProxy = proxy.writeReplace();
                        
                        this.idField = serializableProxy.getClass().getDeclaredField("id");
                        this.idField.setAccessible(true);

                        this.readResolveMethod = serializableProxy.getClass().getDeclaredMethod("readResolve");
                        this.readResolveMethod.setAccessible(true);
                }
                
                public HibernateProxy newProxy(Serializable id) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
                        synchronized (serializableProxy) {
                                idField.set(serializableProxy, id);
                                return (HibernateProxy)readResolveMethod.invoke(serializableProxy);
                        }
                }
        }

        public boolean canEncode(ExtendedObjectOutput out, Object v) {
                Class<?> cls = getClass(out, v);
                return (cls.isAnnotationPresent(Entity.class) || cls.isAnnotationPresent(MappedSuperclass.class));
        }

        public String getEncodedClassName(ExtendedObjectOutput out, Object v) {
        return getClass(out, v).getName();
        }

        public void encode(ExtendedObjectOutput out, Object v) throws IOException, IllegalAccessException, InvocationTargetException {
        String detachedState = null;
        
        if (v instanceof HibernateProxy) {
            HibernateProxy proxy = (HibernateProxy)v;

            // Only write initialized flag, detachedState & id if v is an uninitialized proxy.
            if (proxy.getHibernateLazyInitializer().isUninitialized()) {
                
                Class<?> persistentClass = proxy.getHibernateLazyInitializer().getPersistentClass();
                if (!serializableProxyAdapters.containsKey(persistentClass)) {
                        try {
                                SerializableProxyAdapter proxyAdapter = new SerializableProxyAdapter(proxy);
                                serializableProxyAdapters.putIfAbsent(persistentClass, proxyAdapter);
                        }
                        catch (Exception e) {
                                throw new IOException("Could not create SerializableProxyAdapter for: " + proxy);
                        }
                }
                
                Serializable id = proxy.getHibernateLazyInitializer().getIdentifier();
                log.debug("Writing uninitialized HibernateProxy %s with id %s", detachedState, id);
                
                out.writeBoolean(false);
                out.writeUTF(null);
                out.writeObject(id);
                return;
            }

            // Proxy is initialized, get the underlying persistent object.
                log.debug("Writing initialized HibernateProxy...");
            v = proxy.getHibernateLazyInitializer().getImplementation();
        }

        // Write initialized flag & detachedState.
        out.writeBoolean(true);
        out.writeUTF(null);
                
        // Write all properties in lexical order. 
                List<Property> properties = out.getReflection().findSerializableProperties(v.getClass());
                for (Property property : properties)
                        out.getAndWriteProperty(v, property);
        }

        public boolean canDecode(ExtendedObjectInput in, String className) throws ClassNotFoundException {
                Class<?> cls = in.getReflection().loadClass(className);
                return (cls.isAnnotationPresent(Entity.class) || cls.isAnnotationPresent(MappedSuperclass.class));
        }

        public String getDecodedClassName(ExtendedObjectInput in, String className) {
                return in.getAlias(className);
        }

        public Object newInstance(ExtendedObjectInput in, String className)
                throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException,
                InvocationTargetException, SecurityException, NoSuchMethodException, IOException {
                
                Class<?> cls = in.getReflection().loadClass(className);
                
        // Read initialized flag & detachedState.
                boolean initialized = in.readBoolean();
        in.readUTF();
                
                if (initialized)
                        return in.getReflection().newInstance(cls);
                
        // Create an HibernateProxy.
                SerializableProxyAdapter proxyAdapter = serializableProxyAdapters.get(cls);
                if (proxyAdapter == null)
                        throw new IOException("Could not find SerializableProxyAdapter for: " + cls);
                Serializable id = (Serializable)in.readObject();
                return proxyAdapter.newProxy(id);
        }

        public void decode(ExtendedObjectInput in, Object v) throws IOException, ClassNotFoundException, IllegalAccessException, InvocationTargetException {
                if (!(v instanceof HibernateProxy)) {
                        List<Property> properties = in.getReflection().findSerializableProperties(v.getClass());
                        for (Property property : properties)
                                in.readAndSetProperty(v, property);
                }
        }
        
        protected Class<?> getClass(ExtendedObjectOutput out, Object v) {
        Class<?> cls = v.getClass();
                
        if (v instanceof HibernateProxy) {
                LazyInitializer initializer = ((HibernateProxy)v).getHibernateLazyInitializer();
                
                String className = (
                        initializer.isUninitialized() ?
                        initializer.getEntityName() :
                        initializer.getImplementation().getClass().getName()
                );

                if (className != null && className.length() > 0) {
                try {
                                        cls = out.getReflection().loadClass(className);
                                } catch (ClassNotFoundException e) {
                                cls = initializer.getPersistentClass();
                                }
            }
                }
                
        return cls;
        }
}