/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * 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.exoplatform.services.jcr.impl.core.version;

import org.exoplatform.services.jcr.core.nodetype.NodeTypeDataManager;
import org.exoplatform.services.jcr.dataflow.DataManager;
import org.exoplatform.services.jcr.dataflow.ItemState;
import org.exoplatform.services.jcr.datamodel.InternalQName;
import org.exoplatform.services.jcr.datamodel.ItemType;
import org.exoplatform.services.jcr.datamodel.NodeData;
import org.exoplatform.services.jcr.datamodel.PropertyData;
import org.exoplatform.services.jcr.datamodel.QPath;
import org.exoplatform.services.jcr.datamodel.QPathEntry;
import org.exoplatform.services.jcr.datamodel.ValueData;
import org.exoplatform.services.jcr.impl.Constants;
import org.exoplatform.services.jcr.impl.core.SessionDataManager;
import org.exoplatform.services.jcr.impl.core.SessionImpl;
import org.exoplatform.services.jcr.impl.dataflow.AbstractItemDataCopyVisitor;
import org.exoplatform.services.jcr.impl.dataflow.ItemDataCopyVisitor;
import org.exoplatform.services.jcr.impl.dataflow.ItemDataRemoveVisitor;
import org.exoplatform.services.jcr.impl.dataflow.TransientNodeData;
import org.exoplatform.services.jcr.impl.dataflow.TransientPropertyData;
import org.exoplatform.services.jcr.impl.dataflow.ValueDataUtil;
import org.exoplatform.services.jcr.impl.dataflow.session.SessionChangesLog;
import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;

import javax.jcr.MergeException;
import javax.jcr.RepositoryException;

/**
 * Created by The eXo Platform SAS 06.02.2007 Traverse through merging nodes
 * (destenation) and do merge to correspondent version states.
 * 
 * @author <a href="mailto:peter.nedonosko@exoplatform.com.ua">Peter Nedonosko</a>
 * @version $Id: ItemDataMergeVisitor.java 14100 2008-05-12 10:53:47Z gazarenkov $
 */
public class ItemDataMergeVisitor extends AbstractItemDataCopyVisitor
{

   protected static int NONE = -1;

   protected static int LEAVE = 0;

   protected static int FAIL = 1;

   protected static int UPDATE = 2;

   protected static Log log = ExoLogger.getLogger("exo.jcr.component.core.ItemDataMergeVisitor");

   protected final SessionImpl mergeSession;

   protected final SessionImpl corrSession;

   protected final Map<String, String> failed;

   protected final boolean bestEffort;

   protected final Stack<ContextParent> parents = new Stack<ContextParent>();

   protected final SessionChangesLog changes;

   private class VersionableState
   {
      private final int result;

      private final QPath path;

      private VersionableState(QPath path, int result)
      {
         this.path = path;
         this.result = result;
      }

      public int getResult()
      {
         return result;
      }

      public QPath getPath()
      {
         return path;
      }
   }

   protected class RemoveVisitor extends ItemDataRemoveVisitor
   {
      RemoveVisitor() throws RepositoryException
      {
         super(mergeSession.getTransientNodesManager(), null, mergeSession.getWorkspace().getNodeTypesHolder(),
            mergeSession.getAccessManager(), mergeSession.getUserState());
      }

      @Override
      protected void validateReferential(NodeData node) throws RepositoryException
      {
         // no REFERENCE validation here
      }
   };

   private class ContextParent
   {
      private final NodeData parent;

      private final List<NodeData> corrChildNodes;

      private final int result;

      private ContextParent(NodeData parent, List<NodeData> corrChildNodes, int result)
      {
         this.parent = parent;
         this.corrChildNodes = corrChildNodes;
         this.result = result;
      }

      private ContextParent(NodeData parent, int result)
      {
         this(parent, null, result);
      }

      public NodeData getParent()
      {
         return parent;
      }

      public List<NodeData> getCorrChildNodes()
      {
         return corrChildNodes;
      }

      public int getResult()
      {
         return result;
      }
   }

   public ItemDataMergeVisitor(SessionImpl mergeSession, SessionImpl corrSession, Map<String, String> failed,
      boolean bestEffort)
   {
      super(mergeSession.getTransientNodesManager().getTransactManager());

      this.corrSession = corrSession;
      this.mergeSession = mergeSession;
      this.bestEffort = bestEffort;
      this.failed = failed;

      this.changes = new SessionChangesLog(mergeSession);
   }

   @Override
   protected void entering(NodeData mergeNode, int level) throws RepositoryException
   {

      if (level == 0)
      {
         // initial - merge root node
         doMerge(mergeNode);
      }
      else if (parents.size() > 0)
      {
         ContextParent context = parents.peek();
         if (context.getResult() == UPDATE)
         {
            // doUpdate() work...
            if (context.getCorrChildNodes().remove(mergeNode))
            {
               // let C be the set of nodes in S and in S'
               // for each child node m of n in C domerge(m).
               doMerge(mergeNode);
            }
            else
            {
               // let D be the set of nodes in S but not in S'.
               // remove from n all child nodes in D.
               changes.add(new ItemState(new TransientNodeData(mergeNode.getQPath(), mergeNode.getIdentifier(),
                  mergeNode.getPersistedVersion(), mergeNode.getPrimaryTypeName(), mergeNode.getMixinTypeNames(),
                  mergeNode.getOrderNumber(), mergeNode.getParentIdentifier(), mergeNode.getACL()), ItemState.DELETED,
                  true, context.getParent().getQPath(), true));
            }
         }
         else if (context.getResult() == LEAVE)
         {
            // doLeave() work...
            // for each child node c of n domerge(c).
            doMerge(mergeNode);
         }
         else
         {
            // impossible...
            log.warn("Result is undefined for merge node " + mergeNode.getQPath().getAsString());
         }
      }
      else
      {
         log.warn("Has no parent for merge node " + mergeNode.getQPath().getAsString());
      }
   }

   @Override
   protected void entering(PropertyData mergeProperty, int level) throws RepositoryException
   {
      // remove any property, merged will be added in doMerge() --> doUpdate()
   }

   @Override
   protected void leaving(PropertyData mergeProperty, int level) throws RepositoryException
   {
   }

   @Override
   protected void leaving(NodeData mergeNode, int level) throws RepositoryException
   {
      if (parents.size() > 0)
      {
         ContextParent context = parents.pop();
         if (context.getResult() == UPDATE)
         {
            // for each child node of n' in D' copy it (and its subtree) to n
            // as a new child node (if an incoming node has the same
            // UUID as a node already existing in this workspace,
            // the already existing node is removed).
            SessionDataManager mergeDataManager = mergeSession.getTransientNodesManager();
            for (NodeData corrNode : context.getCorrChildNodes())
            {
               NodeData existedSameIdentifier = (NodeData)mergeDataManager.getItemData(corrNode.getIdentifier());
               if (existedSameIdentifier != null)
               {
                  // if an incoming node has the same
                  // UUID as a node already existing in this workspace,
                  // the already existing node is removed

                  RemoveVisitor remover = new RemoveVisitor();
                  existedSameIdentifier.accept(remover);

                  changes.addAll(remover.getRemovedStates());
               }

               ItemDataCopyVisitor copier =
                  new ItemDataCopyVisitor(context.getParent(), corrNode.getQPath().getName(), mergeSession
                     .getWorkspace().getNodeTypesHolder(), mergeDataManager, mergeDataManager, true);
               corrNode.accept(copier);

               changes.addAll(copier.getItemAddStates());
            }
         }
      }
   }

   // -------------------- merge actions ------------

   protected void doMerge(NodeData mergeNode) throws RepositoryException
   {
      // let n' be the corresponding node of n in ws'.
      // find corr node for this node
      NodeData corrNode = getCorrNodeData(mergeNode);
      if (corrNode != null)
      {

         NodeData mergeVersion = getBaseVersionData(mergeNode, mergeSession);

         if (mergeVersion != null)
         {

            NodeData corrVersion = getBaseVersionData(corrNode, corrSession);

            if (corrVersion != null)
            {
               // let v be base version of n.
               // let v' be base version of n'.

               SessionDataManager mergeDataManager = mergeSession.getTransientNodesManager();

               PropertyData isCheckedOutProperty =
                  (PropertyData)mergeDataManager.getItemData(mergeNode, new QPathEntry(Constants.JCR_ISCHECKEDOUT, 0),
                     ItemType.PROPERTY);

               if (!ValueDataUtil.getBoolean(isCheckedOutProperty.getValues().get(0))
                  && isSuccessor(mergeVersion, corrVersion))
               {
                  // if v' is a successor of v and
                  // n is not checked-in doupdate(n, n').
                  doUpdate(mergeNode, corrNode);
               }
               else if (mergeVersion.getQPath().equals(corrVersion.getQPath())
                  || isPredecessor(mergeVersion, corrVersion))
               {
                  // else if v is equal to or a predecessor of v' doleave(n).
                  doLeave(mergeNode);
               }
               else
               {
                  // else dofail(n, v').
                  doFail(mergeNode, corrVersion);
               }
            }
            else
            {
               // else if n' is not versionable doleave(n)
               doLeave(mergeNode);
            }
         }
         else
         {
            // else if n is not versionable doupdate(n, n')
            doUpdate(mergeNode, corrNode);
         }
      }
      else
      {
         // if no such n' doleave(n).
         doLeave(mergeNode);
      }
   }

   protected void doLeave(NodeData mergeNode) throws RepositoryException
   {
      // for each child node c of n domerge(c).
      // ...back to visitor
      parents.push(new ContextParent(mergeNode, LEAVE));
   }

   protected void doUpdate(NodeData mergeNode, NodeData corrNode) throws RepositoryException
   {

      DataManager mergeDataManager = mergeSession.getTransientNodesManager().getTransactManager();

      QPath mergePath = mergeNode.getQPath();

      TransientNodeData mergedNode =
         new TransientNodeData(mergePath, mergeNode.getIdentifier(), mergeNode.getPersistedVersion(),
            corrNode.getPrimaryTypeName(), corrNode.getMixinTypeNames(), mergeNode.getOrderNumber(),
            mergeNode.getParentIdentifier(), mergeNode.getACL());

      if (!mergeNode.getIdentifier().equals(corrNode.getIdentifier()))
      {

         NodeData existedSameIdentifier = (NodeData)mergeDataManager.getItemData(corrNode.getIdentifier());
         if (existedSameIdentifier != null)
         {
            // if an incoming node has the same
            // UUID as a node already existing in this workspace,
            // the already existing node is removed

            RemoveVisitor remover = new RemoveVisitor();
            existedSameIdentifier.accept(remover);

            changes.addAll(remover.getRemovedStates());
         }
      }

      changes.add(new ItemState(mergedNode, ItemState.UPDATED, true, mergeNode.getQPath(), true));

      // replace set of properties of n with those of n'.
      DataManager corrDataManager = corrSession.getTransientNodesManager().getTransactManager();
      List<PropertyData> corrChildProps = corrDataManager.getChildPropertiesData(corrNode);
      List<PropertyData> mergeChildProps = mergeDataManager.getChildPropertiesData(mergeNode);

      Map<InternalQName, PropertyData> existedProps = new HashMap<InternalQName, PropertyData>();
      for (PropertyData cp : mergeChildProps)
      {
         TransientPropertyData existed =
            new TransientPropertyData(cp.getQPath(), cp.getIdentifier(), cp.getPersistedVersion(), cp.getType(),
               cp.getParentIdentifier(), cp.isMultiValued(), copyValues(cp));
         changes.add(new ItemState(existed, ItemState.DELETED, true, mergedNode.getQPath(), true));

         existedProps.put(existed.getQPath().getName(), existed);
      }

      for (PropertyData cp : corrChildProps)
      {
         PropertyData existed = existedProps.get(cp.getQPath().getName());
         TransientPropertyData mcp =
            new TransientPropertyData(QPath.makeChildPath(mergePath, cp.getQPath().getName()), existed != null
               ? existed.getIdentifier() : cp.getIdentifier(), existed != null ? existed.getPersistedVersion()
               : cp.getPersistedVersion(), cp.getType(), mergedNode.getIdentifier(), cp.isMultiValued(), copyValues(cp));

         changes.add(new ItemState(mcp, ItemState.ADDED, true, mergedNode.getQPath(), true));
      }

      List<NodeData> childNodes = corrDataManager.getChildNodesData(corrNode);
      parents.push(new ContextParent(mergedNode, childNodes, UPDATE));

      // let S be the set of child nodes of n.
      // let S' be the set of child nodes of n'.
      // judging by the name of the child node:
      // let C be the set of nodes in S and in S'
      // let D be the set of nodes in S but not in S'.
      // let D' be the set of nodes in S' but not in S.
      // remove from n all child nodes in D. <<< will occurs in doMerge() on
      // particular child
      // for each child node of n' in D' copy it (and its subtree) to n
      // as a new child node (if an incoming node has the same
      // UUID as a node already existing in this workspace,
      // the already existing node is removed) <<< will occurs in doMerge() on
      // particular child

      // for each child node m of n in C domerge(m).
   }

   protected void doFail(NodeData mergeNode, NodeData corrVersion) throws RepositoryException
   {
      if (bestEffort)
      {
         // else add UUID of v' (if not already present) to the
         // jcr:mergeFailed property of n,
         // add UUID of n to failedset,
         // doleave(n).
         failed.put(mergeNode.getIdentifier(), corrVersion.getIdentifier());
         doLeave(mergeNode);
      }
      else
      {
         // if bestEffort = false throw MergeException
         throw new MergeException("Merging of node "
            + mergeSession.getLocationFactory().createJCRPath(mergeNode.getQPath()).getAsString(false) + " failed");
      }
   }

   // -------------------- utils --------------------

   protected NodeData getBaseVersionData(final NodeData node, final SessionImpl session) throws RepositoryException
   {

      NodeTypeDataManager ntManager = session.getWorkspace().getNodeTypesHolder();
      if (ntManager.isNodeType(Constants.MIX_VERSIONABLE, node.getPrimaryTypeName(), node.getMixinTypeNames()))
      {

         SessionDataManager dmanager = session.getTransientNodesManager();

         PropertyData bvProperty =
            (PropertyData)dmanager.getItemData(node, new QPathEntry(Constants.JCR_BASEVERSION, 0), ItemType.PROPERTY);

         return (NodeData)dmanager.getItemData(ValueDataUtil.getString(bvProperty.getValues().get(0)));
      }

      return null; // non versionable
   }

   protected NodeData getCorrNodeData(final NodeData mergeNode) throws RepositoryException
   {

      final QPath mergePath = mergeNode.getQPath();

      SessionDataManager corrDataManager = corrSession.getTransientNodesManager();
      SessionDataManager mergeDataManager = mergeSession.getTransientNodesManager();
      NodeTypeDataManager mergeNtManager = mergeSession.getWorkspace().getNodeTypesHolder();

      if (mergeNtManager.isNodeType(Constants.MIX_REFERENCEABLE, mergeNode.getPrimaryTypeName(),
         mergeNode.getMixinTypeNames()))
      {
         // by UUID
         return (NodeData)corrDataManager.getItemData(mergeNode.getIdentifier());
      }

      // by location
      for (int i = 1; i <= mergePath.getDepth(); i++)
      {
         final QPath ancesstorPath = mergePath.makeAncestorPath(i);
         NodeData mergeAncestor = (NodeData)mergeDataManager.getItemData(ancesstorPath);
         if (mergeAncestor != null
            && mergeNtManager.isNodeType(Constants.MIX_REFERENCEABLE, mergeAncestor.getPrimaryTypeName(),
               mergeAncestor.getMixinTypeNames()))
         {

            NodeData corrAncestor = (NodeData)corrDataManager.getItemData(mergeAncestor.getIdentifier());
            if (corrAncestor != null)
            {
               QPathEntry[] relPathEntries = mergePath.getRelPath(mergePath.getDepth() - i);
               return (NodeData)corrDataManager.getItemData(corrAncestor, relPathEntries, ItemType.NODE);
            }
         }
      }

      return (NodeData)corrDataManager.getItemData(mergePath);
   }

   /**
    * Is a predecessor of the merge version
    */
   protected boolean isPredecessor(NodeData mergeVersion, NodeData corrVersion) throws RepositoryException
   {
      SessionDataManager mergeDataManager = mergeSession.getTransientNodesManager();

      PropertyData predecessorsProperty =
         (PropertyData)mergeDataManager.getItemData(mergeVersion, new QPathEntry(Constants.JCR_PREDECESSORS, 0),
            ItemType.PROPERTY);

      if (predecessorsProperty != null)
      {
         for (ValueData pv : predecessorsProperty.getValues())
         {
            String pidentifier = ValueDataUtil.getString(pv);

            if (pidentifier.equals(corrVersion.getIdentifier()))
            {
               return true; // got it
            }

            // search in predecessors of the predecessor
            NodeData predecessor = (NodeData)mergeDataManager.getItemData(pidentifier);
            if (predecessor != null)
            {
               if (isPredecessor(predecessor, corrVersion))
               {
                  return true;
               }
            }
            else
            {
               throw new RepositoryException("Merge. Predecessor is not found by uuid " + pidentifier + ". Version "
                  + mergeSession.getLocationFactory().createJCRPath(mergeVersion.getQPath()).getAsString(false));
            }
         }
         // else it's a root version
      }

      return false;
   }

   /**
    * Is a successor of the merge version
    */
   protected boolean isSuccessor(NodeData mergeVersion, NodeData corrVersion) throws RepositoryException
   {
      SessionDataManager mergeDataManager = mergeSession.getTransientNodesManager();

      PropertyData successorsProperty =
         (PropertyData)mergeDataManager.getItemData(mergeVersion, new QPathEntry(Constants.JCR_SUCCESSORS, 0),
            ItemType.PROPERTY);

      if (successorsProperty != null)
      {
         for (ValueData sv : successorsProperty.getValues())
         {
            String sidentifier = ValueDataUtil.getString(sv);

            if (sidentifier.equals(corrVersion.getIdentifier()))
            {
               return true; // got it
            }

            // search in successors of the successor
            NodeData successor = (NodeData)mergeDataManager.getItemData(sidentifier);
            if (successor != null)
            {
               if (isSuccessor(successor, corrVersion))
               {
                  return true;
               }
            }
            else
            {
               throw new RepositoryException("Merge. Ssuccessor is not found by uuid " + sidentifier + ". Version "
                  + mergeSession.getLocationFactory().createJCRPath(mergeVersion.getQPath()).getAsString(false));
            }
         }
         // else it's a end of version graph node
      }

      return false;
   }

   public SessionChangesLog getMergeChanges()
   {
      return changes;
   }
}
