package org.kuali.rice.krms.impl.repository;

 import java.util.HashSet;

 import java.util.Map;

 import java.util.Set;

 import java.util.Map.Entry;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 import org.kuali.rice.krms.framework.repository.ContextDefinition;

 import org.kuali.rice.krms.framework.repository.RuleRepository;

 /**

  * This impl has some concurrency issues to consider 

  * @author gilesp

  *

  */

 public class SimpleRuleRepositoryImpl implements RuleRepository {

         ConcurrentMap<String, Set<ContextDefinition>> contextDefinitions = new ConcurrentHashMap<String, Set<ContextDefinition>>();

         @Override

         public ContextDefinition selectContext(Map<String, String> contextQualifiers) {

                 Set<ContextDefinition> results = null;

                 if (contextQualifiers != null) for (Entry<String,String> entry : contextQualifiers.entrySet()) {

                         Set<ContextDefinition> qualifierMatches = contextDefinitions.get(entry.getKey()+"="+entry.getValue());

                         if (null == results) {

                                 results = new HashSet<ContextDefinition>(qualifierMatches);

                         } else {

                                 results.retainAll(qualifierMatches);

                         }

                 }

                 if (results != null) {

                         if (results.size() == 1) return results.iterator().next();

                         else throw new IllegalArgumentException("ambiguous qualifiers");

                 }

                 return null;

         }

         public void addContextDefinitionMapping(Map<String, String> contextQualifiers, ContextDefinition contextDefinition) {

                 if (contextQualifiers != null) for (Entry<String,String> entry : contextQualifiers.entrySet()) {

                         String key = entry.getKey()+"="+entry.getValue();

                         // TODO: synchronize here

                         contextDefinitions.putIfAbsent(key, new HashSet<ContextDefinition>());

                         contextDefinitions.get(key).add(contextDefinition);

                 }

         }

 }