/**
    * Copyright 2005-2011 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.krad.datadictionary.validation.processor;
  
  import org.kuali.rice.core.api.util.RiceKeyConstants;
  import org.kuali.rice.krad.datadictionary.DataObjectEntry;
  import org.kuali.rice.krad.datadictionary.exception.AttributeValidationException;
  import org.kuali.rice.krad.datadictionary.validation.AttributeValueReader;
  import org.kuali.rice.krad.datadictionary.validation.DictionaryObjectAttributeValueReader;
  import org.kuali.rice.krad.datadictionary.validation.ValidationUtils;
  import org.kuali.rice.krad.datadictionary.validation.constraint.Constraint;
  import org.kuali.rice.krad.datadictionary.validation.constraint.ExistenceConstraint;
  import org.kuali.rice.krad.datadictionary.validation.result.ConstraintValidationResult;
  import org.kuali.rice.krad.datadictionary.validation.result.DictionaryValidationResult;
  import org.kuali.rice.krad.datadictionary.validation.result.ProcessorResult;
  
  /**
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org) 
   */
  public class ExistenceConstraintProcessor extends OptionalElementConstraintProcessor<ExistenceConstraint> {
  
  	private static final String CONSTRAINT_NAME = "existence constraint";
  	
  	/**
  	 * @see org.kuali.rice.krad.datadictionary.validation.processor.ConstraintProcessor#process(DictionaryValidationResult, Object, org.kuali.rice.krad.datadictionary.validation.Validatable, org.kuali.rice.krad.datadictionary.validation.AttributeValueReader)
  	 */
  	@Override
  	public ProcessorResult process(DictionaryValidationResult result, Object value, ExistenceConstraint constraint, AttributeValueReader attributeValueReader) throws AttributeValidationException {
  
  		// To accommodate the needs of other processors, the ConstraintProcessor.process() method returns a list of ConstraintValidationResult objects
  		// but since a definition that is existence constrained only provides a single isRequired field, there is effectively a single constraint
  		// being imposed.
  		return new ProcessorResult(processSingleExistenceConstraint(result, value, constraint, attributeValueReader));
  	}
  
  	@Override 
  	public String getName() {
  		return CONSTRAINT_NAME;
  	}
  	
  	/**
  	 * @see org.kuali.rice.krad.datadictionary.validation.processor.ConstraintProcessor#getConstraintType()
  	 */
  	@Override
  	public Class<? extends Constraint> getConstraintType() {
  		return ExistenceConstraint.class;
  	}
  
  	protected ConstraintValidationResult processSingleExistenceConstraint(DictionaryValidationResult result, Object value, ExistenceConstraint constraint, AttributeValueReader attributeValueReader) throws AttributeValidationException {
  		// If it's not set, then there's no constraint
  		if (constraint.isRequired() == null)
  			return result.addNoConstraint(attributeValueReader, CONSTRAINT_NAME);
  		
  		if (constraint.isRequired().booleanValue() && !skipConstraint(attributeValueReader)) {
  			// If this attribute is required and the value is null then 
  			if (ValidationUtils.isNullOrEmpty(value)) 
  				return result.addError(attributeValueReader, CONSTRAINT_NAME, RiceKeyConstants.ERROR_REQUIRED);
  			
  			return result.addSuccess(attributeValueReader, CONSTRAINT_NAME);
  		}
  
  		return result.addSkipped(attributeValueReader, CONSTRAINT_NAME);
  	}
  
      /**
       * Checks to see if existence constraint should be skipped.  Required constraint should be skipped if it is an attribute of a complex
       * attribute and the complex attribute is not required.
       * 
       * @param attributeValueReader
       * @return
       */
      private boolean skipConstraint(AttributeValueReader attributeValueReader) {
          boolean skipConstraint = false;
          if (attributeValueReader instanceof DictionaryObjectAttributeValueReader){
              DictionaryObjectAttributeValueReader dictionaryValueReader = (DictionaryObjectAttributeValueReader)attributeValueReader;
              skipConstraint = dictionaryValueReader.isNestedAttribute() && dictionaryValueReader.isParentAttributeNull();
          }
          return skipConstraint;
      }
  	
  	
  }