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

 import java.util.HashMap;

 import java.util.Map;

 import org.kuali.rice.krms.api.engine.ExecutionOptions;

 import org.kuali.rice.krms.api.engine.SelectionCriteria;

 import org.kuali.rice.krms.api.engine.Term;

 import org.kuali.rice.krms.api.repository.RuleRepositoryService;

 import org.kuali.rice.krms.api.repository.context.ContextDefinition;

 import org.kuali.rice.krms.api.repository.context.ContextSelectionCriteria;

 import org.kuali.rice.krms.framework.engine.Context;

 import org.kuali.rice.krms.framework.engine.ContextProvider;

 public class RuleRepositoryContextProvider implements ContextProvider {

         // may want to move these out to a constants file somewhere so they are accessible to engine clients?

         private static final String NAME_CONTEXT_QUALIFIER = "name";

         private static final String NAMESPACE_CODE_CONTEXT_QUALIFIER = "namespaceCode";

         private RuleRepositoryService ruleRepositoryService;

         private RepositoryToEngineTranslator repositoryToEngineTranslator;

         @Override

         public Context loadContext(SelectionCriteria selectionCriteria, Map<Term, Object> facts, ExecutionOptions executionOptions) {

                 ContextSelectionCriteria contextSelectionCriteria = constructContextSelectionCriteria(selectionCriteria);

                 ContextDefinition contextDefinition = ruleRepositoryService.selectContext(contextSelectionCriteria);

                 // TODO should have an execution option that throws an error here if a context does not exist?

                 if (contextDefinition != null) {

                         return loadContextFromDefinition(contextDefinition);

                 }

                 return null;

         }

         protected Context loadContextFromDefinition(ContextDefinition contextDefinition) {

                 return repositoryToEngineTranslator.translateContextDefinition(contextDefinition);

         }

         public void setRuleRepositoryService(RuleRepositoryService ruleRepositoryService) {

                 this.ruleRepositoryService = ruleRepositoryService;

         }

         public void setRepositoryToEngineTranslator(RepositoryToEngineTranslator repositoryToEngineTranslator) {

                 this.repositoryToEngineTranslator = repositoryToEngineTranslator;

         }

         protected ContextSelectionCriteria constructContextSelectionCriteria(SelectionCriteria selectionCriteria) {

                 Map<String, String> givenContextQualifiers = selectionCriteria.getContextQualifiers();

                 if (givenContextQualifiers == null || givenContextQualifiers.isEmpty()) {

                         throw new IllegalArgumentException("Context qualifiers in the selection criteria were null or empty.  At least one context qualifier must be passed in selection criteria.");

                 }

                 // extract the "standard" context qualifiers for the rule repository, name and namespaceCode

                 String namespaceCode = null;

                 String name = null;

                 Map<String, String> contextQualifiers = new HashMap<String, String>();

                 for (String key : givenContextQualifiers.keySet()) {

                         String value = givenContextQualifiers.get(key);

                         if (key.equals(NAME_CONTEXT_QUALIFIER)) {

                                 name = value;

                         } else if (key.equals(NAMESPACE_CODE_CONTEXT_QUALIFIER)) {

                                 namespaceCode = value;

                         } else {

                                 contextQualifiers.put(key, value);

                         }

                 }

                 return ContextSelectionCriteria.newCriteria(namespaceCode, name, contextQualifiers);

         }

 }