/**
    * Copyright 2005-2016 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.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(org.kuali.rice.krad.datadictionary.validation.result.DictionaryValidationResult,
       *      Object, org.kuali.rice.krad.datadictionary.validation.constraint.Constraint,
       *      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)) {
                  String errorParameter = attributeValueReader.getLabel(attributeValueReader.getAttributeName());
                  if (ValidationUtils.isNullOrEmpty(errorParameter)) {
                      errorParameter = attributeValueReader.getAttributeName();
                  }
                  return result.addError(attributeValueReader, CONSTRAINT_NAME, RiceKeyConstants.ERROR_REQUIRED,
                          errorParameter);
              }
              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 true if the constraint should be skipped
       */
      private boolean skipConstraint(AttributeValueReader attributeValueReader) {
          boolean skipConstraint = false;
          if (attributeValueReader instanceof DictionaryObjectAttributeValueReader) {
              DictionaryObjectAttributeValueReader dictionaryValueReader =
                     (DictionaryObjectAttributeValueReader) attributeValueReader;
             skipConstraint = dictionaryValueReader.isNestedAttribute() && dictionaryValueReader.isParentAttributeNull();
         }
         return skipConstraint;
     }
 
 }