/**
    * Copyright 2005-2012 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.krms.impl.repository;
  
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.core.api.criteria.CriteriaLookupService;
  import org.kuali.rice.core.api.criteria.GenericQueryResults;
  import org.kuali.rice.core.api.criteria.Predicate;
  import org.kuali.rice.core.api.criteria.QueryByCriteria;
  import org.kuali.rice.krad.service.BusinessObjectService;
  import org.kuali.rice.krad.service.KRADServiceLocator;
  import org.kuali.rice.krms.api.repository.RuleRepositoryService;
  import org.kuali.rice.krms.api.repository.agenda.AgendaTreeDefinition;
  import org.kuali.rice.krms.api.repository.agenda.AgendaTreeRuleEntry;
  import org.kuali.rice.krms.api.repository.agenda.AgendaTreeSubAgendaEntry;
  import org.kuali.rice.krms.api.repository.context.ContextDefinition;
  import org.kuali.rice.krms.api.repository.context.ContextSelectionCriteria;
  import org.kuali.rice.krms.api.repository.rule.RuleDefinition;
  import org.kuali.rice.krms.impl.util.KrmsImplConstants.PropertyNames;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import static org.kuali.rice.core.api.criteria.PredicateFactory.*;
  
  /**
   * NOTE: This is a patched version of this class which fixes a bug in Rice 2.0.0 releated to execution of
   * an agenda with no rules.
   */
  public class RuleRepositoryServiceImpl implements RuleRepositoryService {
      protected BusinessObjectService businessObjectService;
      private CriteriaLookupService criteriaLookupService;
  	
  	/**
  	 * This overridden method ...
  	 * 
  	 * @see org.kuali.rice.krms.api.repository.RuleRepositoryService#selectContext(org.kuali.rice.krms.api.repository.context.ContextSelectionCriteria)
  	 */
      @Override
      public ContextDefinition selectContext(
      		ContextSelectionCriteria contextSelectionCriteria) {
      	if (contextSelectionCriteria == null){
      		throw new IllegalArgumentException("selection criteria is null");
      	}
      	if (StringUtils.isBlank(contextSelectionCriteria.getNamespaceCode())){
      		throw new IllegalArgumentException("selection criteria namespaceCode is null or blank");
      	}
      	QueryByCriteria queryCriteria = buildQuery(contextSelectionCriteria);
          GenericQueryResults<ContextBo> results = getCriteriaLookupService().lookup(ContextBo.class, queryCriteria);
  
      	List<ContextBo> resultBos = results.getResults();
  
      	//assuming 1 ?
      	ContextDefinition result = null;
      	if (resultBos != null) {
      		if (resultBos.size() == 1) {
      			ContextBo bo = resultBos.iterator().next();
      			return ContextBo.to(bo);
      		}
      		else throw new IllegalArgumentException("ambiguous qualifiers");
      	}
      	return result;
      }
  
  	@Override
  	public AgendaTreeDefinition getAgendaTree(String agendaId) {
  		if (StringUtils.isBlank(agendaId)){
      		throw new IllegalArgumentException("agenda id is null or blank");
      	}
  		// Get agenda items from db, then build up agenda tree structure
  		AgendaBo agendaBo = getBusinessObjectService().findBySinglePrimaryKey(AgendaBo.class, agendaId);
  		String agendaItemId = agendaBo.getFirstItemId();
  		
  		// walk thru the agenda items, building an agenda tree definition Builder along the way
  		AgendaTreeDefinition.Builder myBuilder = AgendaTreeDefinition.Builder.create();
  		myBuilder.setAgendaId( agendaId );
  		
  		if (agendaItemId != null) {
  			myBuilder = walkAgendaItemTree(agendaItemId, myBuilder);
  		}
  		
  		// build the agenda tree and return it
  		return myBuilder.build();
  	}
 	
 	@Override
 	public List<AgendaTreeDefinition> getAgendaTrees(List<String> agendaIds) {
 		List<AgendaTreeDefinition> agendaTrees = new ArrayList<AgendaTreeDefinition>();
 		for (String agendaId : agendaIds){
 			agendaTrees.add( getAgendaTree(agendaId) );
 		}
         return Collections.unmodifiableList(agendaTrees);		
 	}
 	
 	@Override
 	public RuleDefinition getRule(String ruleId) {
 		if (StringUtils.isBlank(ruleId)){
 			return null;			
 		}
 		RuleBo bo = getBusinessObjectService().findBySinglePrimaryKey(RuleBo.class, ruleId);
 		return RuleBo.to(bo);
 	}
 	
 	@Override
 	public List<RuleDefinition> getRules(List<String> ruleIds) {
         if (ruleIds == null) throw new IllegalArgumentException("ruleIds must not be null");
 
         // Fetch BOs
         List<RuleBo> bos = null;
         if (ruleIds.size() == 0) {
             bos = Collections.emptyList();
         } else {
             QueryByCriteria.Builder qBuilder = QueryByCriteria.Builder.create();
             List<Predicate> pList = new ArrayList<Predicate>();
             qBuilder.setPredicates(in("id", ruleIds.toArray()));
             GenericQueryResults<RuleBo> results = getCriteriaLookupService().lookup(RuleBo.class, qBuilder.build());
 
     	    bos = results.getResults();
     	}
 
         // Translate BOs
         ArrayList<RuleDefinition> rules = new ArrayList<RuleDefinition>();
         for (RuleBo bo : bos) {
             RuleDefinition rule = RuleBo.to(bo);
             rules.add(rule);
         }
         return Collections.unmodifiableList(rules);
 	}
 
 	/**
 	 * Recursive method to create AgendaTreeDefinition builder
 	 * 	
 	 *  
 	 */
 	private AgendaTreeDefinition.Builder walkAgendaItemTree(String agendaItemId, AgendaTreeDefinition.Builder builder){
 		//TODO: prevent circular, endless looping
 		if (StringUtils.isBlank(agendaItemId)){
 			return null;
 		}
 		// Get AgendaItemDefinition Business Object from database
 		// NOTE: if we read agendaItem one at a time from db.   Could consider linking in OJB and getting all at once
 		AgendaItemBo agendaItemBo = getBusinessObjectService().findBySinglePrimaryKey(AgendaItemBo.class, agendaItemId);
 		
 		// If Rule  
 		// TODO: validate that only either rule or subagenda, not both
 		if (!StringUtils.isBlank( agendaItemBo.getRuleId() )){
 			// setup new rule entry builder
 			AgendaTreeRuleEntry.Builder ruleEntryBuilder = AgendaTreeRuleEntry.Builder
 					.create(agendaItemBo.getId(), agendaItemBo.getRuleId());
 			ruleEntryBuilder.setRuleId( agendaItemBo.getRuleId() );
 			ruleEntryBuilder.setAgendaItemId( agendaItemBo.getId() );
 			if (agendaItemBo.getWhenTrueId() != null){
 				// Go follow the true branch, creating AgendaTreeDefinintion Builder for the
 				// true branch level
 				AgendaTreeDefinition.Builder myBuilder = AgendaTreeDefinition.Builder.create();
 				myBuilder.setAgendaId( agendaItemBo.getAgendaId() );
 				ruleEntryBuilder.setIfTrue( walkAgendaItemTree(agendaItemBo.getWhenTrueId(),myBuilder));
 			}
 			if (agendaItemBo.getWhenFalseId() != null){
 				// Go follow the false branch, creating AgendaTreeDefinintion Builder 
 				AgendaTreeDefinition.Builder myBuilder = AgendaTreeDefinition.Builder.create();
 				myBuilder.setAgendaId( agendaItemBo.getAgendaId() );
 				ruleEntryBuilder.setIfFalse( walkAgendaItemTree(agendaItemBo.getWhenFalseId(), myBuilder));
 			}
 			// Build the Rule Entry and add it to the AgendaTreeDefinition builder
 			builder.addRuleEntry( ruleEntryBuilder.build() );
 		}
 		// if SubAgenda and a sub agenda tree entry
 		if (!StringUtils.isBlank(agendaItemBo.getSubAgendaId())) {
 			AgendaTreeSubAgendaEntry.Builder subAgendaEntryBuilder = 
 				AgendaTreeSubAgendaEntry.Builder.create(agendaItemBo.getId(), agendaItemBo.getSubAgendaId());
 			builder.addSubAgendaEntry( subAgendaEntryBuilder.build() );
 			}
 
 		// if this agenda item has an "After Id", follow that branch
 		if (!StringUtils.isBlank( agendaItemBo.getAlwaysId() )){
 			builder = walkAgendaItemTree( agendaItemBo.getAlwaysId(), builder);
 			
 		}
 		return builder;
 	}
 	
 	/**
 	 * 
 	 * This method converts a {@link ContextSelectionCriteria} object into a
 	 * {@link QueryByCriteria} object with the proper predicates for AttributeBo properties.
 	 * 
 	 * @param selectionCriteria
 	 * @return 
 	 */
 	private QueryByCriteria buildQuery( ContextSelectionCriteria selectionCriteria ){
 		Predicate p;
 		QueryByCriteria.Builder qBuilder = QueryByCriteria.Builder.create();
     	List<Predicate> pList = new ArrayList<Predicate>();
     	if (selectionCriteria.getNamespaceCode() != null){
     		p = equal(PropertyNames.Context.NAMESPACE, selectionCriteria.getNamespaceCode());
     		pList.add(p);
     	}
     	if (selectionCriteria.getName() != null){
     		p = equal(PropertyNames.Context.NAME, selectionCriteria.getName());
     		pList.add(p);
     	}
     	if (selectionCriteria.getContextQualifiers() != null){
     		for (Map.Entry<String, String> entry : selectionCriteria.getContextQualifiers().entrySet()){
     			p = and(equal(PropertyNames.Context.ATTRIBUTE_BOS
     					+ "." + PropertyNames.BaseAttribute.ATTRIBUTE_DEFINITION
     					+ "." + PropertyNames.KrmsAttributeDefinition.NAME, entry.getKey()),
     				equal(PropertyNames.Context.ATTRIBUTE_BOS
     					+ "." + PropertyNames.BaseAttribute.VALUE, entry.getValue()));
     			pList.add(p);
     		}
     	}
      	Predicate[] preds = new Predicate[pList.size()];
      	pList.toArray(preds);
     	qBuilder.setPredicates(and(preds)); 
 		return qBuilder.build();
 	}
 
 	/**
      * Sets the businessObjectService property.
      *
      * @param businessObjectService The businessObjectService to set.
      */
     public void setBusinessObjectService(final BusinessObjectService businessObjectService) {
         this.businessObjectService = businessObjectService;
     }
 
     protected BusinessObjectService getBusinessObjectService() {
 		if ( businessObjectService == null ) {
             // TODO: inject this instead
 			businessObjectService = KRADServiceLocator.getBusinessObjectService();
 		}
 		return businessObjectService;
 	}
     
     /**
      * Sets the criteriaLookupService attribute value.
      *
      * @param criteriaLookupService The criteriaLookupService to set.
      */
     public void setCriteriaLookupService(final CriteriaLookupService criteriaLookupService) {
         this.criteriaLookupService = criteriaLookupService;
     }
 
     protected CriteriaLookupService getCriteriaLookupService() {
         return criteriaLookupService;
     }
     
 }