/*
  GRANITE DATA SERVICES
  Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.

  This file is part of Granite Data Services.

  Granite Data Services is free software; you can redistribute it and/or modify
  it under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 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 Library General Public License
  for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

package org.granite.tide.spring;

import java.util.HashMap;
import java.util.Map;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.granite.gravity.Gravity;
import org.granite.logging.Logger;
import org.granite.tide.data.DataContext;
import org.granite.tide.data.DataEnabled;
import org.granite.tide.data.DataEnabled.PublishMode;
import org.granite.tide.data.DataUpdatePostprocessor;
import org.granite.tide.data.TideSynchronizationManager;
import org.granite.util.TypeUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.support.TransactionSynchronizationAdapter;
import org.springframework.transaction.support.TransactionSynchronizationManager;

/**
 * Spring AOP interceptor to handle publishing of data changes instead of relying on the default behaviour
 * This can be used outside of a HTTP Granite context and inside the security/transaction context
 * 
 * Ensure that the order of the interceptor is correctly setup to use ON_COMMIT publish mode: this interceptor must be executed inside a transaction
 *  
 * @author William DRAI
 */
public class TideDataPublishingInterceptor implements MethodInterceptor {
        
        private static final Logger log = Logger.getLogger(TideDataPublishingInterceptor.class);
        
        private Gravity gravity;
        private DataUpdatePostprocessor dataUpdatePostprocessor;
        
        private Map<String, TideSynchronizationManager> syncsMap = new HashMap<String, TideSynchronizationManager>();
        
        public TideDataPublishingInterceptor() {
                try {
                        syncsMap.put("org.springframework.orm.hibernate3.SessionHolder", TypeUtil.newInstance("org.granite.tide.spring.Hibernate3SynchronizationManager", TideSynchronizationManager.class));
                }
                catch (Throwable e) {
                        // Hibernate 3 not present
                }
                try {
                        syncsMap.put("org.springframework.orm.hibernate4.SessionHolder", TypeUtil.newInstance("org.granite.tide.spring.Hibernate4SynchronizationManager", TideSynchronizationManager.class));
                }
                catch (Throwable e) {
                        // Hibernate 4 not present
                }
                try {
                        syncsMap.put("org.springframework.orm.jpa.EntityManagerHolder", TypeUtil.newInstance("org.granite.tide.spring.JPASynchronizationManager", TideSynchronizationManager.class));
                }
                catch (Throwable e) {
                        // JPA not present
                }
        }
        
        
        public void setGravity(Gravity gravity) {
                this.gravity = gravity;
        }
        
        @Autowired(required=false)
        public void setDataUpdatePostprocessor(DataUpdatePostprocessor dataUpdatePostprocessor) {
                this.dataUpdatePostprocessor = dataUpdatePostprocessor;
        }
        
    public Object invoke(final MethodInvocation invocation) throws Throwable {
        DataEnabled dataEnabled = invocation.getThis().getClass().getAnnotation(DataEnabled.class);
        if (dataEnabled == null || !dataEnabled.useInterceptor())
                return invocation.proceed();
        
        boolean shouldRemoveContextAtEnd = DataContext.get() == null;
        boolean shouldInitContext = shouldRemoveContextAtEnd || DataContext.isNull();
        boolean onCommit = false;
        
        if (shouldInitContext) {
                DataContext.init(gravity, dataEnabled.topic(), dataEnabled.params(), dataEnabled.publish());
                if (dataUpdatePostprocessor != null)
                        DataContext.get().setDataUpdatePostprocessor(dataUpdatePostprocessor);
        }
        
        DataContext.observe();
        try {
                if (dataEnabled.publish().equals(PublishMode.ON_COMMIT) && !TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
                         if (TransactionSynchronizationManager.isSynchronizationActive()) {
                                 boolean registered = false;
                                 for (Object resource : TransactionSynchronizationManager.getResourceMap().values()) {
                                         if (syncsMap.containsKey(resource.getClass().getName())) {
                                                 registered = syncsMap.get(resource.getClass().getName()).registerSynchronization(resource, shouldRemoveContextAtEnd);
                                                 break;
                                         }
                                 }
                                 if (!registered)
                                         TransactionSynchronizationManager.registerSynchronization(new DataPublishingTransactionSynchronization(shouldRemoveContextAtEnd));
                                 else if (shouldRemoveContextAtEnd)
                                                 TransactionSynchronizationManager.registerSynchronization(new DataContextCleanupTransactionSynchronization());
                                 onCommit = true;
                         }
                         else {
                                 log.error("Could not register synchronization for ON_COMMIT publish mode, check that the Spring PlatformTransactionManager supports it "
                                                 + "and that the order of the TransactionInterceptor is lower than the order of TideDataPublishingInterceptor");
                         }
                }
                
                Object ret = invocation.proceed();
                
                DataContext.publish(PublishMode.ON_SUCCESS);
                return ret;
        }
        finally {
                if (shouldRemoveContextAtEnd && !onCommit)
                        DataContext.remove();
        }
    }
    
    private static class DataPublishingTransactionSynchronization extends TransactionSynchronizationAdapter {
        
        private boolean removeContext = false;
        
        public DataPublishingTransactionSynchronization(boolean removeContext) {
                this.removeContext = removeContext;
        }

                @Override
                public void beforeCommit(boolean readOnly) {
                        if (!readOnly)
                                DataContext.publish(PublishMode.ON_COMMIT);
                }
                
                @Override
                public void beforeCompletion() {
                        if (removeContext)
                                DataContext.remove();
                }
                
                @Override
                public void afterCompletion(int status) {
                        if (removeContext)
                                DataContext.remove();
                }
    }

    private static class DataContextCleanupTransactionSynchronization extends TransactionSynchronizationAdapter {
        
                @Override
                public void afterCompletion(int status) {
                        DataContext.remove();
                }
    }
}