/**
    * 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.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);
  		
  	}
  
  }