/*
 * Copyright (C) 2005-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco 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 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco 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 Alfresco. If not, see <http://www.gnu.org/licenses/>.
 */
package org.alfresco.repo.version;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.alfresco.model.ContentModel;
import org.alfresco.repo.batch.BatchProcessor;
import org.alfresco.repo.batch.BatchProcessor.BatchProcessWorkerAdaptor;
import org.alfresco.repo.domain.hibernate.SessionSizeResourceManager;
import org.alfresco.repo.domain.qname.QNameDAO;
import org.alfresco.repo.node.MLPropertyInterceptor;
import org.alfresco.repo.policy.BehaviourFilter;
import org.alfresco.repo.policy.PolicyScope;
import org.alfresco.repo.security.authentication.AuthenticationUtil;
import org.alfresco.repo.transaction.AlfrescoTransactionSupport;
import org.alfresco.repo.transaction.RetryingTransactionHelper;
import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
import org.alfresco.repo.version.common.VersionUtil;
import org.alfresco.service.cmr.dictionary.ClassDefinition;
import org.alfresco.service.cmr.dictionary.DictionaryService;
import org.alfresco.service.cmr.dictionary.PropertyDefinition;
import org.alfresco.service.cmr.repository.AssociationRef;
import org.alfresco.service.cmr.repository.ChildAssociationRef;
import org.alfresco.service.cmr.repository.NodeRef;
import org.alfresco.service.cmr.repository.NodeService;
import org.alfresco.service.cmr.repository.StoreRef;
import org.alfresco.service.cmr.rule.RuleService;
import org.alfresco.service.cmr.version.Version;
import org.alfresco.service.cmr.version.VersionHistory;
import org.alfresco.service.namespace.QName;
import org.alfresco.service.namespace.RegexQNamePattern;
import org.alfresco.service.transaction.TransactionService;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.extensions.surf.util.I18NUtil;

/**
 * Version2 Migrator
 */
public class VersionMigrator implements ApplicationEventPublisherAware
{
    protected static Log logger = LogFactory.getLog(VersionMigrator.class);
    
    public static final StoreRef VERSION_STORE_REF_OLD = new StoreRef(StoreRef.PROTOCOL_WORKSPACE, VersionModel.STORE_ID);
    public static final StoreRef VERSION_STORE_REF_NEW = new StoreRef(StoreRef.PROTOCOL_WORKSPACE, Version2Model.STORE_ID);
    
    private static final String MSG_PATCH_NOOP = "version_service.migration.patch.noop";
    private static final String MSG_PATCH_COMPLETE = "version_service.migration.patch.complete";
    private static final String MSG_PATCH_SKIP1 = "version_service.migration.patch.warn.skip1";
    private static final String MSG_PATCH_SKIP2 = "version_service.migration.patch.warn.skip2";
    
    private static final String MSG_DELETE_COMPLETE = "version_service.migration.delete.complete";
    private static final String MSG_DELETE_SKIP1    = "version_service.migration.delete.warn.skip1";
    private static final String MSG_DELETE_SKIP2    = "version_service.migration.delete.warn.skip2";
    
    private static boolean busy = false;
    
    public final static String PREFIX_MIGRATED = "migrated-";
    
    private VersionServiceImpl version1Service = new VersionServiceImpl();
    
    private Version2ServiceImpl version2Service;
    private NodeService dbNodeService;
    private BehaviourFilter policyBehaviourFilter;
    private DictionaryService dictionaryService;
    private TransactionService transactionService;
    private NodeService versionNodeService; // NodeService impl which redirects to appropriate VersionService
    private QNameDAO qnameDAO;
    private RuleService ruleService;
    private ApplicationEventPublisher applicationEventPublisher;
    
    private int loggingInterval = 500;
    
    public void setVersion2ServiceImpl(Version2ServiceImpl versionService)
    {
        this.version2Service = versionService;
    }
    
    public void setDbNodeService(NodeService nodeService)
    {
        this.dbNodeService = nodeService;
    }
    
    public void setPolicyBehaviourFilter(BehaviourFilter policyBehaviourFilter)
    {
        this.policyBehaviourFilter = policyBehaviourFilter;
    }
    
    public void setDictionaryService(DictionaryService dictionaryService)
    {
        this.dictionaryService = dictionaryService;
    }
    
    public void setTransactionService(TransactionService transactionService)
    {
        this.transactionService = transactionService;
    }
    
    public void setVersionNodeService(NodeService versionNodeService)
    {
        this.versionNodeService = versionNodeService;
    }
    
    public void setQnameDAO(QNameDAO qnameDAO)
    {
        this.qnameDAO = qnameDAO;
    }
    
    public void setRuleService(RuleService ruleService)
    {
        this.ruleService = ruleService;
    }
    
    public void setLoggingInterval(int loggingInterval)
    {
        this.loggingInterval = loggingInterval;
    }
    
    public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) 
    {
        this.applicationEventPublisher = applicationEventPublisher;
    }
    
    
    public void init()
    {
        version1Service.setNodeService(dbNodeService);
        version1Service.setDbNodeService(dbNodeService);
        
        version2Service.setDbNodeService(dbNodeService);
    }
    
    public NodeRef migrateVersionHistory(NodeRef oldVHNodeRef, NodeRef versionedNodeRef)
    {
        /*
        if (logger.isTraceEnabled())
        {
            logger.trace("migrateVersionHistory: oldVersionHistoryRef = " + oldVHNodeRef);
        }
        */
        
        VersionHistory vh = v1BuildVersionHistory(oldVHNodeRef, versionedNodeRef);
        
        // create new version history node
        NodeRef newVHNodeRef = v2CreateVersionHistory(versionedNodeRef);
        
        Version[] oldVersions = (Version[])vh.getAllVersions().toArray(new Version[]{});
        
        // Disable auditable behaviour - so that migrated versions maintain their original auditable properties (eg. created, creator)
        this.policyBehaviourFilter.disableBehaviour(ContentModel.ASPECT_AUDITABLE);
        
        try
        {
            for (int i = (oldVersions.length-1); i >= 0; i--)
            {
                // migrate versions
                v2CreateNewVersion(newVHNodeRef, oldVersions[i]);
            }
        }
        finally
        {
            // Enable auditable behaviour
            this.policyBehaviourFilter.enableBehaviour(ContentModel.ASPECT_AUDITABLE);
        }
        
        return newVHNodeRef;
    }
    
    private NodeRef v2CreateVersionHistory(NodeRef nodeRef)
    {
        return version2Service.createVersionHistory(nodeRef);
    }
    
    private NodeRef v2CreateNewVersion(NodeRef newVersionHistoryRef, Version oldVersion)
    {
        NodeRef versionedNodeRef = oldVersion.getVersionedNodeRef();     // nodeRef to versioned node in live store
        NodeRef frozenStateNodeRef = oldVersion.getFrozenStateNodeRef(); // nodeRef to version node in version store
        
        /*
        if (logger.isTraceEnabled())
        {
            logger.trace("v2CreateNewVersion: oldVersionRef = " + frozenStateNodeRef + " " + oldVersion);
        }
        */
        
        String versionLabel = oldVersion.getVersionLabel();
        String versionDescription = oldVersion.getDescription();
        
        QName sourceType = versionNodeService.getType(frozenStateNodeRef);
        Set<QName> nodeAspects = versionNodeService.getAspects(frozenStateNodeRef);
        Map<QName, Serializable> nodeProperties = versionNodeService.getProperties(frozenStateNodeRef);
        List<ChildAssociationRef> nodeChildAssocs = versionNodeService.getChildAssocs(frozenStateNodeRef);
        List<AssociationRef> nodeAssocs = versionNodeService.getTargetAssocs(frozenStateNodeRef, RegexQNamePattern.MATCH_ALL);
        
        long nodeDbId = (Long)nodeProperties.get(ContentModel.PROP_NODE_DBID);
        
        // ALFCOM-2658
        nodeProperties.put(ContentModel.PROP_NODE_UUID, frozenStateNodeRef.getId());
        
        int versionNumber = 0;
        
        // get oldVersion auditable properties (of the version node itself, rather than the live versioned node)
        NodeRef versionNode = VersionUtil.convertNodeRef(frozenStateNodeRef);
        Date versionCreated = (Date)dbNodeService.getProperty(versionNode, ContentModel.PROP_CREATED);
        String versionCreator = (String)dbNodeService.getProperty(versionNode, ContentModel.PROP_CREATOR);
        Date versionModified = (Date)dbNodeService.getProperty(versionNode, ContentModel.PROP_MODIFIED);
        String versionModifier = (String)dbNodeService.getProperty(versionNode, ContentModel.PROP_MODIFIER);
        Date versionAccessed = (Date)dbNodeService.getProperty(versionNode, ContentModel.PROP_ACCESSED);
        
        Map<String, Serializable> versionMetaDataProperties = version1Service.getVersionMetaData(versionNode);
        
        // Create the node details
        PolicyScope nodeDetails = new PolicyScope(sourceType);
        
        // add properties
        for (Map.Entry<QName, Serializable> entry : nodeProperties.entrySet())
        {
            nodeDetails.addProperty(sourceType, entry.getKey(), entry.getValue());
        }
        
        // add aspects
        for (QName aspect : nodeAspects)
        {
            // add aspect
            nodeDetails.addAspect(aspect);
            
            // copy the aspect properties
            ClassDefinition classDefinition = dictionaryService.getClass(aspect);
            if (classDefinition != null)
            {  
                Map<QName,PropertyDefinition> propertyDefinitions = classDefinition.getProperties();
                for (QName propertyName : propertyDefinitions.keySet())
                {
                    Serializable propValue = nodeProperties.get(propertyName);
                    nodeDetails.addProperty(aspect, propertyName, propValue);
                }
            }
        }
        
        // add child assocs (since 3.3 Ent - applies only to direct upgrade from 2.x to 3.3 Ent or higher)
        for (ChildAssociationRef childAssoc : nodeChildAssocs)
        {
            nodeDetails.addChildAssociation(sourceType, childAssoc);
        }
        
        // add target assocs (since 3.3 Ent - applies only to direct upgrade from 2.x to 3.3 Ent or higher)
        for (AssociationRef assoc : nodeAssocs)
        {
            nodeDetails.addAssociation(sourceType, assoc);
        }
        
        NodeRef newVersionRef = version2Service.createNewVersion(
                sourceType,
                newVersionHistoryRef,
                version2Service.getStandardVersionProperties(versionedNodeRef, nodeDbId, nodeAspects, versionNumber, versionLabel, versionDescription),
                versionMetaDataProperties,
                versionNumber,
                nodeDetails);
        
        // set newVersion auditable properties (of the version node itself, rather than the live versioned node)
        Map<QName, Serializable> props = dbNodeService.getProperties(newVersionRef);
        props.put(ContentModel.PROP_CREATED, versionCreated);
        props.put(ContentModel.PROP_CREATOR, versionCreator);
        props.put(ContentModel.PROP_MODIFIED, versionModified);
        props.put(ContentModel.PROP_MODIFIER, versionModifier);
        props.put(ContentModel.PROP_ACCESSED, versionAccessed);
        dbNodeService.setProperties(newVersionRef, props);
        
        return newVersionRef;
    }
    
    protected NodeRef v1GetVersionedNodeRef(NodeRef oldVersionHistoryRef)
    {
        NodeRef versionedNodeRef = null;
        
        // Get versioned nodeRef from one of the versions - note: assumes all versions refer to the same versioned nodeRef
        Collection<ChildAssociationRef> versions = dbNodeService.getChildAssocs(oldVersionHistoryRef);
        if (versions.size() > 0)
        {
            Iterator<ChildAssociationRef> itr = versions.iterator();
            ChildAssociationRef childAssocRef = itr.next();
            NodeRef versionRef = childAssocRef.getChildRef();
            
            Version version = version1Service.getVersion(versionRef);
            
            versionedNodeRef = version.getVersionedNodeRef();
        }
        
        return versionedNodeRef;
    }
    
    private VersionHistory v1BuildVersionHistory(NodeRef oldVersionHistoryRef, NodeRef versionedNodeRef)
    {  
        return version1Service.buildVersionHistory(oldVersionHistoryRef, versionedNodeRef);
    }
    
    protected void v1DeleteVersionHistory(NodeRef oldVersionHistoryRef)
    {
        dbNodeService.deleteNode(oldVersionHistoryRef);
    }
    
    private void v1MarkVersionHistory(NodeRef oldVersionHistoryRef)
    {
        String migratedName = PREFIX_MIGRATED+oldVersionHistoryRef.getId();
        dbNodeService.setProperty(oldVersionHistoryRef, ContentModel.PROP_NAME, migratedName);
    }
    
    public List<ChildAssociationRef> getVersionHistories(final NodeRef rootNodeRef)
    {
        return dbNodeService.getChildAssocs(rootNodeRef);
    }
    
    private void migrateVersion(NodeRef oldVHNodeRef, boolean deleteImmediately) throws Throwable
    {
        NodeRef versionedNodeRef = v1GetVersionedNodeRef(oldVHNodeRef);
        migrateVersionHistory(oldVHNodeRef, versionedNodeRef);
        
        if (deleteImmediately)
        {
            // delete old version history node
            v1DeleteVersionHistory(oldVHNodeRef);
        }
        else
        {
            // mark old version history node for later cleanup
            v1MarkVersionHistory(oldVHNodeRef);
        }
    }
    
    /**
     * Do the Version migration work
     * @return          Returns <tt>true</tt> if the work is done
     */
    public boolean migrateVersions(int batchSize, int threadCount, final boolean deleteImmediately)
    {
        transactionService.getRetryingTransactionHelper().doInTransaction(new RetryingTransactionCallback<Object>()
        {
            public Object execute() throws Throwable
            {
                // pre-create new qnames (rather than retry initial batches)
                qnameDAO.getOrCreateQName(Version2Model.ASPECT_VERSION_STORE_ROOT);
                qnameDAO.getOrCreateQName(Version2Model.TYPE_QNAME_VERSION_HISTORY);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_VERSIONED_NODE_ID);
                qnameDAO.getOrCreateQName(Version2Model.ASPECT_VERSION);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_VERSION_LABEL);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_VERSION_NUMBER);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_NODE_REF);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_NODE_DBID);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_CREATOR);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_CREATED);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_MODIFIER);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_MODIFIED);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_FROZEN_ACCESSED);
                qnameDAO.getOrCreateQName(Version2Model.ASSOC_SUCCESSOR);
                qnameDAO.getOrCreateQName(Version2Model.CHILD_QNAME_VERSION_HISTORIES);
                qnameDAO.getOrCreateQName(Version2Model.CHILD_QNAME_VERSIONS);
                qnameDAO.getOrCreateQName(Version2Model.CHILD_QNAME_VERSIONED_ASSOCS);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_ASSOC_DBID);
                qnameDAO.getOrCreateQName(Version2Model.PROP_QNAME_TRANSLATION_VERSIONS);
                
                return null;
            }
        }, false, true);
        
        final NodeRef oldRootNodeRef = dbNodeService.getRootNode(VersionMigrator.VERSION_STORE_REF_OLD);
        final NodeRef newRootNodeRef = dbNodeService.getRootNode(VersionMigrator.VERSION_STORE_REF_NEW);
        
        
        long startTime = System.currentTimeMillis();
        
        final List<ChildAssociationRef> childAssocRefs = getVersionHistories(oldRootNodeRef);
        
        int toDo = childAssocRefs.size();
        
        if (toDo == 0)
        {
            logger.info(I18NUtil.getMessage(MSG_PATCH_NOOP));
            return true;
        }
        
        if (logger.isInfoEnabled())
        {
            logger.info("Found "+childAssocRefs.size()+" version histories in old version store (in "+((System.currentTimeMillis()-startTime)/1000)+" secs)");
        }
        
        if (logger.isDebugEnabled())
        {
            logger.debug("batchSize="+batchSize+", batchWorkerThreadCount="+threadCount+", deleteImmediately="+deleteImmediately);
        }
        
        long splitTime = System.currentTimeMillis();
        
        final List<ChildAssociationRef> newChildAssocRefs = getVersionHistories(newRootNodeRef);
        final boolean firstMigration = (newChildAssocRefs.size() == 0);
        
        if (logger.isInfoEnabled())
        {
            if (! firstMigration)
            {
                logger.warn("This is not the first migration attempt. Found "+newChildAssocRefs.size()+" version histories in new version store (in "+((System.currentTimeMillis()-splitTime)/1000)+" secs)");
            }
        }
        
        // note: assumes patch runs before cleanup starts
        
        int alreadyMigratedCount = 0;
        int batchErrorCount = 0;
        int batchCount = 0;
        
        boolean wasMLAware = MLPropertyInterceptor.setMLAware(true);
        SessionSizeResourceManager.setDisableInTransaction();
        
        try
        {
            //
            // split into batches (ignore version histories that have already been migrated)
            //
            
            splitTime = System.currentTimeMillis();
            
            int totalCount = 0;
            Collection<List<NodeRef>> batchProcessorWork = new ArrayList<List<NodeRef>>(2);
            
            final List<NodeRef> tmpBatch = new ArrayList<NodeRef>(batchSize);
            
            for (final ChildAssociationRef childAssocRef : childAssocRefs)
            {
                totalCount++;
                
                // short-cut if first migration
                if (!firstMigration)
                {
                    if (isMigrated(childAssocRef))
                    {
                        // skip - already migrated
                        alreadyMigratedCount++;
                        continue;
                    }
                }
                
                if (tmpBatch.size() < batchSize)
                {
                    tmpBatch.add(childAssocRef.getChildRef());
                }
                
                if ((tmpBatch.size() == batchSize) || (totalCount == childAssocRefs.size()))
                {
                    // Each thread gets 1 batch to execute
                    batchProcessorWork.add(new ArrayList<NodeRef>(tmpBatch));
                    tmpBatch.clear();
                }
            }
            
            batchCount = batchProcessorWork.size();
            
            if (batchCount > 0)
            {
                if (logger.isDebugEnabled())
                {
                    logger.debug("Split into "+batchCount+" batches in "+(System.currentTimeMillis()-splitTime)+" ms");
                }
                
                //
                // do the work
                //
                
                final String runAsUser = AuthenticationUtil.getRunAsUser();
                
                BatchProcessWorkerAdaptor<List<NodeRef>> batchProcessorWorker = new BatchProcessWorkerAdaptor<List<NodeRef>>()
                {
                    public void beforeProcess() throws Throwable
                    {
                        // Disable rules
                        ruleService.disableRules();
                        
                        // Authentication
                        AuthenticationUtil.setRunAsUser(runAsUser);
                    }

                    public void afterProcess() throws Throwable
                    {
                        // Enable rules
                        ruleService.enableRules();
                        // Clear authentication
                        AuthenticationUtil.clearCurrentSecurityContext();
                    }
                    
                    public void process(List<NodeRef> vhBatch) throws Throwable
                    {
                        long startTime = System.currentTimeMillis();
                        
                        for (NodeRef oldVHNodeRef : vhBatch)
                        {
                            migrateVersion(oldVHNodeRef, deleteImmediately);
                        }
                        
                        if (logger.isTraceEnabled())
                        {
                            logger.trace("Migrated batch of "+vhBatch.size()+" version histories in "+(System.currentTimeMillis()-startTime)+ " ms ["+AlfrescoTransactionSupport.getTransactionId()+"]["+Thread.currentThread().getId()+"]");
                        }
                    }
                };
                
                BatchProcessor<List<NodeRef>> batchProcessor = new BatchProcessor<List<NodeRef>>(
                        "MigrateVersionStore",
                        transactionService.getRetryingTransactionHelper(),
                        batchProcessorWork, threadCount, 1,
                        applicationEventPublisher, logger, loggingInterval);
                
                boolean splitTxns = true;
                batchProcessor.process(batchProcessorWorker, splitTxns);
                
                batchErrorCount = batchProcessor.getTotalErrors();
            }
        }
        finally
        {
            MLPropertyInterceptor.setMLAware(wasMLAware);
            SessionSizeResourceManager.setEnableInTransaction();
        }
        
        
        if (alreadyMigratedCount > 0)
        {
            logger.warn(I18NUtil.getMessage(MSG_PATCH_SKIP2, alreadyMigratedCount));
        }
        
        if (batchCount > 0)
        {
            if (batchErrorCount > 0)
            {
                logger.warn(I18NUtil.getMessage(MSG_PATCH_SKIP1, batchErrorCount, batchCount, ((System.currentTimeMillis()-startTime)/1000)));
            }
            else
            {
                logger.info(I18NUtil.getMessage(MSG_PATCH_COMPLETE, (toDo - alreadyMigratedCount), toDo, ((System.currentTimeMillis()-startTime)/1000)));
            }
        }
        
        return (batchErrorCount == 0);
    }
    
    
    public void executeCleanup(final int batchSize, final int threadCount)
    {
        if (! busy)
        {
            try
            {
                busy = true;
                
                final RetryingTransactionHelper txHelper = transactionService.getRetryingTransactionHelper();
                txHelper.setMaxRetries(1);
                txHelper.doInTransaction(new RetryingTransactionCallback<Object>()
                {
                    public Object execute() throws Throwable
                    {
                        long startTime = System.currentTimeMillis();
                        
                        NodeRef oldRootNodeRef = dbNodeService.getRootNode(VersionMigrator.VERSION_STORE_REF_OLD);
                        List<ChildAssociationRef> childAssocRefs = getVersionHistories(oldRootNodeRef);
                        
                        int toDo = childAssocRefs.size();
                        
                        if (toDo > 0)
                        {
                            if (logger.isInfoEnabled())
                            {
                                logger.info("Found "+toDo+" version histories to delete from old version store (in "+((System.currentTimeMillis()-startTime)/1000)+" secs)");
                            }
                            
                            // note: assumes cleanup runs after patch has completed
                            
                            int notMigratedCount = 0;
                            int batchErrorCount = 0;
                            int batchCount = 0;
                            
                            boolean wasMLAware = MLPropertyInterceptor.setMLAware(true);
                            SessionSizeResourceManager.setDisableInTransaction();
                            
                            try
                            {
                                //
                                // split into batches
                                //
                                
                                long splitTime = System.currentTimeMillis();
                                
                                int totalCount = 0;
                                
                                Collection<List<NodeRef>> batchProcessorWork = new ArrayList<List<NodeRef>>(2);
                                final List<NodeRef> tmpBatch = new ArrayList<NodeRef>(batchSize);
                                
                                for (final ChildAssociationRef childAssocRef : childAssocRefs)
                                {
                                    totalCount++;
                                    
                                    if (! isMigrated(childAssocRef))
                                    {
                                       notMigratedCount++;
                                    }
                                    else
                                    {
                                        if (tmpBatch.size() < batchSize)
                                        {
                                            tmpBatch.add(childAssocRef.getChildRef());
                                        }
                                        
                                        if ((tmpBatch.size() == batchSize) || (totalCount == childAssocRefs.size()))
                                        {
                                            // Each thread gets 1 batch to execute
                                            batchProcessorWork.add(new ArrayList<NodeRef>(tmpBatch));
                                            tmpBatch.clear();
                                        }
                                    }
                                }
                                
                                batchCount = batchProcessorWork.size();
                                
                                if (batchCount > 0)
                                {
                                    if (logger.isInfoEnabled())
                                    {
                                        logger.info("Split into "+batchCount+" batches in "+(System.currentTimeMillis()-splitTime)+" ms");
                                    }
                                    
                                    //
                                    // do the work
                                    //
                                    
                                    BatchProcessWorkerAdaptor<List<NodeRef>> batchProcessorWorker = new BatchProcessWorkerAdaptor<List<NodeRef>>()
                                    {
                                        public void process(List<NodeRef> vhBatch) throws Throwable
                                        {
                                            long startTime = System.currentTimeMillis();
                                            
                                            for (NodeRef oldVHNodeRef : vhBatch)
                                            {
                                                // delete old version history node
                                                v1DeleteVersionHistory(oldVHNodeRef);
                                            }
                                            
                                            if (logger.isTraceEnabled())
                                            {
                                                logger.trace("Deleted batch of "+vhBatch.size()+" migrated version histories in "+(System.currentTimeMillis()-startTime)+ " ms ["+AlfrescoTransactionSupport.getTransactionId()+"]["+Thread.currentThread().getId()+"]");
                                            }
                                        }
                                    };
                                    
                                    BatchProcessor<List<NodeRef>> batchProcessor = new BatchProcessor<List<NodeRef>>(
                                            "MigrateVersionStore",
                                            transactionService.getRetryingTransactionHelper(),
                                            batchProcessorWork, threadCount, 1,
                                            applicationEventPublisher, logger, loggingInterval);
                                    
                                    boolean splitTxns = true;
                                    batchProcessor.process(batchProcessorWorker, splitTxns);
                                    
                                    batchErrorCount = batchProcessor.getTotalErrors();
                                }
                            }
                            finally
                            {
                                MLPropertyInterceptor.setMLAware(wasMLAware);
                                SessionSizeResourceManager.setEnableInTransaction();
                            }
                            
                            if (notMigratedCount > 0)
                            {
                                logger.warn(I18NUtil.getMessage(MSG_DELETE_SKIP2, notMigratedCount));
                            }
                            
                            if (batchCount > 0)
                            {
                                if (batchErrorCount > 0)
                                {
                                    logger.warn(I18NUtil.getMessage(MSG_DELETE_SKIP1, batchErrorCount, ((System.currentTimeMillis()-startTime)/1000)));
                                }
                                else
                                {
                                    logger.info(I18NUtil.getMessage(MSG_DELETE_COMPLETE, (toDo - notMigratedCount), toDo, ((System.currentTimeMillis()-startTime)/1000)));
                                }
                            }
                        }
                        
                        return null;
                    }
                }, true, true);
            }
            finally
            {
                busy = false;
            }
        }
    }
    
    protected boolean isMigrated(ChildAssociationRef vhChildAssocRef)
    {
        return (((String)dbNodeService.getProperty(vhChildAssocRef.getChildRef(), ContentModel.PROP_NAME)).startsWith(VersionMigrator.PREFIX_MIGRATED));
    }
}