/**
    * Copyright 2005-2011 The Kuali Foundation
    *
    * Licensed under the Educational Community License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.opensource.org/licenses/ecl2.php
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.kuali.rice.kew.engine.transition;
  
  import org.kuali.rice.kew.engine.RouteContext;
  import org.kuali.rice.kew.engine.RouteHelper;
  import org.kuali.rice.kew.engine.node.Node;
  import org.kuali.rice.kew.engine.node.ProcessResult;
  import org.kuali.rice.kew.engine.node.RouteNode;
  import org.kuali.rice.kew.engine.node.RouteNodeInstance;
  
  import java.util.ArrayList;
  import java.util.List;
  
  
  /**
   * Common superclass for all Transition Engines.  A TransitionEngine handles transitioning into and out of
   * a {@link RouteNodeInstance}.  The TransitionEngine is also responsible for determining if a Node has completed.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public abstract class TransitionEngine {
      
  	private RouteHelper helper;
  	
  	public RouteNodeInstance transitionTo(RouteNodeInstance nextNodeInstance, RouteContext context) throws Exception {
  		return nextNodeInstance;
  	}
      
      /**
       * Tell the WorkflowEngine processing the activeNodeInstance if the node is complete and transitionFrom can 
       * be called.
       *
       * @return boolean
       * @param context for routing
       * @throws Exception
       */
      public abstract ProcessResult isComplete(RouteContext context) throws Exception;
  	
      public Transition transitionFrom(RouteContext context, ProcessResult processResult) throws Exception {
          return new Transition(resolveNextNodeInstances(context.getNodeInstance()));
      }
      
      protected void setRouteHelper(RouteHelper helper) {
      	this.helper = helper;
      }
      
      protected RouteHelper getRouteHelper() {
      	return helper;
      }
      
      protected Node getNode(RouteNode routeNode, Class nodeClass) throws Exception {
  		return helper.getNode(routeNode);
      }
      
      /**
       * Determines the next nodes instances for the transition.  If the node instance already
       * has next nodes instances (i.e. a dynamic node), then those will be returned.  Otherwise
       * it will resolve the next nodes from the RouteNode prototype.
       * @param nodeInstance for the transition
       * @param nextRouteNodes list of route notes
       * @return list of route note instances
       */
      protected List<RouteNodeInstance> resolveNextNodeInstances(RouteNodeInstance nodeInstance, List<RouteNode> nextRouteNodes) {
          List<RouteNodeInstance> nextNodeInstances = new ArrayList<RouteNodeInstance>();
          for (RouteNode nextRouteNode : nextRouteNodes)
          {
              RouteNode nextNode = (RouteNode) nextRouteNode;
              RouteNodeInstance nextNodeInstance = getRouteHelper().getNodeFactory().createRouteNodeInstance(nodeInstance.getDocumentId(), nextNode);
              nextNodeInstance.setBranch(nodeInstance.getBranch());
              nextNodeInstance.setProcess(nodeInstance.getProcess());
              nextNodeInstances.add(nextNodeInstance);
          }
          return nextNodeInstances;
      }
      
      protected List<RouteNodeInstance> resolveNextNodeInstances(RouteNodeInstance nodeInstance) {
          return resolveNextNodeInstances(nodeInstance, nodeInstance.getRouteNode().getNextNodes());
      }
      
  }