/**
    * Copyright 2005-2013 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.node;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.commons.collections.CollectionUtils;
  import org.kuali.rice.coreservice.framework.parameter.ParameterService;
  import org.kuali.rice.coreservice.framework.CoreFrameworkServiceLocator;
  import org.kuali.rice.kew.actionrequest.ActionRequestValue;
  import org.kuali.rice.kew.engine.RouteContext;
  import org.kuali.rice.kew.engine.RouteHelper;
  import org.kuali.rice.kew.exception.RouteManagerException;
  import org.kuali.rice.kew.api.exception.WorkflowException;
  import org.kuali.rice.kew.routeheader.DocumentRouteHeaderValue;
  import org.kuali.rice.kew.routemodule.RouteModule;
  import org.kuali.rice.kew.service.KEWServiceLocator;
  import org.kuali.rice.kew.util.ClassDumper;
  import org.kuali.rice.kew.api.KewApiConstants;
  import org.kuali.rice.krad.util.KRADConstants;
  
  /**
   * A node which generates {@link ActionRequestValue} objects from a
   * {@link RouteModule}.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class RequestsNode extends RequestActivationNode {
  
  	private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger
  			.getLogger( RequestsNode.class );
  
  	protected static final String SUPPRESS_POLICY_ERRORS_KEY = "_suppressPolicyErrorsRequestActivationNode";
  
  	public final SimpleResult process(RouteContext routeContext, RouteHelper routeHelper)
  			throws Exception {
  		try {
              if (processCustom(routeContext, routeHelper)) {
                  return super.process(routeContext, routeHelper);
              }
              RouteNodeInstance nodeInstance = routeContext.getNodeInstance();
              boolean isInitial = nodeInstance.isInitial();
              int currentIteration = 0;
              List<ActionRequestValue> requestsGenerated = new ArrayList<ActionRequestValue>();
              while (true) {
                  detectRunawayProcess(routeContext, currentIteration++);
                  if (isInitial) {
                      requestsGenerated = generateRequests(routeContext);
                      // need to set to false because we could iterate more than once here when the node is still in
                      // "initial" state
                      isInitial = false;
                  }
                  SimpleResult simpleResult = super.process(routeContext, routeHelper);
                  if (simpleResult.isComplete()) {
                      RouteModule routeModule = getRouteModule(routeContext);
                      boolean moreRequestsAvailable = routeModule.isMoreRequestsAvailable(routeContext);
                      if (!moreRequestsAvailable) {
                          applyPoliciesOnExit(requestsGenerated, routeContext);
                          return simpleResult;
                      } else {
                          requestsGenerated = generateRequests(routeContext);
                      }
                  } else {
                      return simpleResult;
                  }
              }
  		} catch ( RouteManagerException ex ) {
  			// just re-throw - no need to wrap
  			throw ex;
  		} catch ( Exception e ) {
  			LOG.error( "Caught exception routing", e );
  			throw new RouteManagerException( e.getMessage(), e, routeContext );
  		}
  	}
  
      protected List<ActionRequestValue> generateRequests(RouteContext routeContext) throws Exception {
          DocumentRouteHeaderValue document = routeContext.getDocument();
  		RouteNodeInstance nodeInstance = routeContext.getNodeInstance();
  		RouteNode node = nodeInstance.getRouteNode();
          if (LOG.isDebugEnabled()) {
              LOG.debug("RouteHeader info inside routing loop\n" + ClassDumper.dumpFields(document));
              LOG.debug("Looking for new actionRequests - routeLevel: " + node.getRouteNodeName());
         }
         boolean suppressPolicyErrors = isSuppressingPolicyErrors(routeContext);
         List<ActionRequestValue> requests = getNewActionRequests(routeContext);
         // determine if we have any approve requests for FinalApprover checks
         if (!suppressPolicyErrors) {
             verifyFinalApprovalRequest(document, requests, nodeInstance, routeContext);
         }
         return requests;
     }
 
     /**
      * Applies policies that should get checked prior to transitioning out of this node.  The default implementation of
      * this method checks the "mandatory" policy.
      *
      * @param requestsGenerated the requests generated on the current iteration of the route module
      * @param routeContext the current route context
      */
     protected void applyPoliciesOnExit(List<ActionRequestValue> requestsGenerated, RouteContext routeContext) {
         DocumentRouteHeaderValue document = routeContext.getDocument();
         RouteNodeInstance nodeInstance = routeContext.getNodeInstance();
         RouteNode node = nodeInstance.getRouteNode();
         // for mandatory routes, requests must be generated
         if (node.isMandatory() && !isSuppressingPolicyErrors(routeContext) && CollectionUtils.isEmpty(requestsGenerated)) {
             List<ActionRequestValue> actionRequests = KEWServiceLocator.getActionRequestService().findRootRequestsByDocIdAtRouteNode(document.getDocumentId(), nodeInstance.getRouteNodeInstanceId());
             if (actionRequests.isEmpty()) {
                 LOG.warn("no requests generated for mandatory route - " + node.getRouteNodeName());
                 throw new RouteManagerException(
                     "No requests generated for mandatory route " + node.getRouteNodeName() + ":" + node
                             .getRouteMethodName(), routeContext);
             }
         }
     }
 
     /** Used by subclasses to replace the functioning of the process method.
 	 * 
 	 * @return <b>true</b> if custom processing was performed and the base implementation
 	 * in {@link #process(RouteContext, RouteHelper)} should be skipped.
 	 */
 	protected boolean processCustom(RouteContext routeContext, RouteHelper routeHelper) throws Exception {
 		return false;
 	}
 	
 	/**
 	 * Verifies the state of the action requests when a final approval action is involved.
 	 * 
 	 * Throws a RouteManagerException if actions were not generated correctly.
 	 */
 	protected void verifyFinalApprovalRequest( DocumentRouteHeaderValue document, List<ActionRequestValue> requests, RouteNodeInstance nodeInstance, RouteContext routeContext ) throws RouteManagerException {
 		boolean pastFinalApprover = isPastFinalApprover( document, nodeInstance );
 		boolean hasApproveRequest = false;
 		for ( ActionRequestValue actionRequest : requests ) {
 			if ( actionRequest.isApproveOrCompleteRequest() ) {
 				hasApproveRequest = true;
 				break;
 			}
 		}
 		// if final approver route level and no approve request send to
 		// exception routing
 		if ( nodeInstance.getRouteNode().getFinalApprovalInd().booleanValue() ) {
 			// we must have an approve request generated if final
 			// approver level.
 			if ( !hasApproveRequest ) {
 				throw new RouteManagerException(
 						"No Approve Request generated after final approver", routeContext );
 			}
 		} else if ( pastFinalApprover ) {
 			// we can't allow generation of approve requests after final
 			// approver. This guys going to exception routing.
 			if ( hasApproveRequest ) {
 				throw new RouteManagerException(
 						"Approve Request generated after final approver", routeContext );
 			}
 		}
 	}
 
 	public List<ActionRequestValue> getNewActionRequests(RouteContext context) throws Exception {
 		RouteNodeInstance nodeInstance = context.getNodeInstance();
 		String routeMethodName = nodeInstance.getRouteNode().getRouteMethodName();
 		if ( LOG.isDebugEnabled() ) {
 			LOG.debug( "Looking for action requests in " + routeMethodName + " : "
 					+ nodeInstance.getRouteNode().getRouteNodeName() );
 		}
 		List<ActionRequestValue> newRequests = new ArrayList<ActionRequestValue>();
 		try {
 			RouteModule routeModule = getRouteModule( context );
 			List<ActionRequestValue> requests = routeModule.findActionRequests( context );
 			for ( ActionRequestValue actionRequest : requests ) {
 				if ( LOG.isDebugEnabled() ) {
 					LOG.debug( "Request generated by RouteModule '" + routeModule + "' for node "
 							+ nodeInstance + ":" + actionRequest );
 				}
 				actionRequest = KEWServiceLocator.getActionRequestService()
 						.initializeActionRequestGraph( actionRequest, context.getDocument(),
 								nodeInstance );
 				saveActionRequest( context, actionRequest );
 				newRequests.add( actionRequest );
 			}
 		} catch ( WorkflowException ex ) {
 			LOG.warn( "Caught WorkflowException during routing", ex );
 			throw new RouteManagerException( ex, context );
 		}
 		return newRequests;
 	}
 
 	/**
 	 * Returns the RouteModule which should handle generating requests for this
 	 * RequestsNode.
 	 */
 	protected RouteModule getRouteModule(RouteContext context) throws Exception {
 		return KEWServiceLocator.getRouteModuleService().findRouteModule(
 				context.getNodeInstance().getRouteNode() );
 	}
 
 	/**
 	 * Checks if the document has past the final approver node by walking
 	 * backward through the previous node instances. Ignores any previous nodes
 	 * that have been "revoked".
 	 */
 	protected boolean isPastFinalApprover(DocumentRouteHeaderValue document,
 			RouteNodeInstance nodeInstance) {
 		FinalApproverContext context = new FinalApproverContext();
 		List revokedNodeInstances = KEWServiceLocator.getRouteNodeService()
 				.getRevokedNodeInstances( document );
 		Set revokedNodeInstanceIds = new HashSet();
 		for ( Iterator iterator = revokedNodeInstances.iterator(); iterator.hasNext(); ) {
 			RouteNodeInstance revokedNodeInstance = (RouteNodeInstance)iterator.next();
 			revokedNodeInstanceIds.add( revokedNodeInstance.getRouteNodeInstanceId() );
 		}
 		isPastFinalApprover( nodeInstance.getPreviousNodeInstances(), context,
 				revokedNodeInstanceIds );
 		return context.isPast;
 	}
 
 	protected void isPastFinalApprover(List previousNodeInstances, FinalApproverContext context,
 			Set revokedNodeInstanceIds) {
 		if ( previousNodeInstances != null && !previousNodeInstances.isEmpty() ) {
 			for ( Iterator iterator = previousNodeInstances.iterator(); iterator.hasNext(); ) {
 				if ( context.isPast ) {
 					return;
 				}
 				RouteNodeInstance nodeInstance = (RouteNodeInstance)iterator.next();
 				if ( context.inspected.contains( getKey( nodeInstance ) ) ) {
 					continue;
 				} else {
 					context.inspected.add( getKey( nodeInstance ) );
 				}
 				if ( Boolean.TRUE.equals( nodeInstance.getRouteNode().getFinalApprovalInd() ) ) {
 					// if the node instance has been revoked (by a Return To
 					// Previous action for example)
 					// then we don't want to consider that node when we
 					// determine if we are past final
 					// approval or not
 					if ( !revokedNodeInstanceIds.contains( nodeInstance.getRouteNodeInstanceId() ) ) {
 						context.isPast = true;
 					}
 					return;
 				}
 				isPastFinalApprover( nodeInstance.getPreviousNodeInstances(), context,
 						revokedNodeInstanceIds );
 			}
 		}
 	}
 
 	/**
 	 * The method will get a key value which can be used for comparison
 	 * purposes. If the node instance has a primary key value, it will be
 	 * returned. However, if the node instance has not been saved to the
 	 * database (i.e. during a simulation) this method will return the node
 	 * instance passed in.
 	 */
 	protected Object getKey(RouteNodeInstance nodeInstance) {
 		String id = nodeInstance.getRouteNodeInstanceId();
 		return (id != null ? (Object)id : (Object)nodeInstance);
 	}
 
     protected void detectRunawayProcess(RouteContext routeContext, int currentIteration) throws NumberFormatException {
 	    String maxNodesConstant = getParameterService().getParameterValueAsString(KewApiConstants.KEW_NAMESPACE, KRADConstants.DetailTypes.ALL_DETAIL_TYPE, KewApiConstants.MAX_NODES_BEFORE_RUNAWAY_PROCESS);
 	    int maxNodes = (org.apache.commons.lang.StringUtils.isEmpty(maxNodesConstant)) ? 50 : Integer.valueOf(maxNodesConstant);
 	    if (currentIteration > maxNodes) {
             throw new RouteManagerException("Detected a runaway process within RequestsNode for document with id '" + routeContext.getDocument().getDocumentId() + "' after " + currentIteration + " iterations.");
         }
 	}
 
 	protected class FinalApproverContext {
 		public Set inspected = new HashSet();
 
 		public boolean isPast = false;
 	}
 
 	public static boolean isSuppressingPolicyErrors(RouteContext routeContext) {
 		Boolean suppressPolicyErrors = (Boolean)routeContext.getParameters().get(
 				SUPPRESS_POLICY_ERRORS_KEY );
 		if ( suppressPolicyErrors == null || !suppressPolicyErrors ) {
 			return false;
 		}
 		return true;
 	}
 
 	@SuppressWarnings("unchecked")
 	public static void setSuppressPolicyErrors(RouteContext routeContext) {
 		routeContext.getParameters().put( SUPPRESS_POLICY_ERRORS_KEY, Boolean.TRUE );
 	}
 
     protected ParameterService getParameterService() {
 		return CoreFrameworkServiceLocator.getParameterService();
 	}
 }