/**
 * 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.ValidationUtils;
import org.kuali.rice.krad.datadictionary.validation.ValidationUtils.Result;
import org.kuali.rice.krad.datadictionary.validation.constraint.CollectionSizeConstraint;
import org.kuali.rice.krad.datadictionary.validation.constraint.Constraint;
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;

import java.util.Collection;

/**
 * This class validates attributes that are collection size constrained - ones that can only have between x and y number 
 * 
 * @author Kuali Rice Team (rice.collab@kuali.org) 
 */
public class CollectionSizeConstraintProcessor implements CollectionConstraintProcessor<Collection<?>, CollectionSizeConstraint> {

        private static final String CONSTRAINT_NAME = "collection size constraint";
        
        /**
         * @see org.kuali.rice.krad.datadictionary.validation.processor.ConstraintProcessor#process(DictionaryValidationResult, Object, org.kuali.rice.krad.datadictionary.validation.capability.Validatable, org.kuali.rice.krad.datadictionary.validation.AttributeValueReader)
         */
        @Override
        public ProcessorResult process(DictionaryValidationResult result, Collection<?> collection, CollectionSizeConstraint 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 collection size constrained only provides a single max and minimum, there is effectively a single constraint
                // being imposed.
        return new ProcessorResult(processSingleCollectionSizeConstraint(result, collection, 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 CollectionSizeConstraint.class;
        }

        /**
         * @see org.kuali.rice.krad.datadictionary.validation.processor.ConstraintProcessor#isOptional()
         */
        @Override
        public boolean isOptional() {
                return false;
        }

        protected ConstraintValidationResult processSingleCollectionSizeConstraint(DictionaryValidationResult result, Collection<?> collection, CollectionSizeConstraint constraint, AttributeValueReader attributeValueReader) throws AttributeValidationException {           
            Integer sizeOfCollection = new Integer(0);
            if (collection != null){
                sizeOfCollection = Integer.valueOf(collection.size());
            }
                
                Integer maxOccurances = constraint.getMaximumNumberOfElements();
                Integer minOccurances = constraint.getMinimumNumberOfElements();
                
                Result lessThanMax = ValidationUtils.isLessThanOrEqual(sizeOfCollection, maxOccurances);
                Result greaterThanMin = ValidationUtils.isGreaterThanOrEqual(sizeOfCollection, minOccurances);

                // It's okay for one end of the range to be undefined - that's not an error. It's only an error if one of them is invalid 
        if (lessThanMax != Result.INVALID && greaterThanMin != Result.INVALID) { 
                // Of course, if they're both undefined then we didn't actually have a real constraint
                if (lessThanMax == Result.UNDEFINED && greaterThanMin == Result.UNDEFINED)
                        return result.addNoConstraint(attributeValueReader, CONSTRAINT_NAME);
                
                // In this case, we've succeeded
                return result.addSuccess(attributeValueReader, CONSTRAINT_NAME);
        }
        
                String maxErrorParameter = maxOccurances != null ? maxOccurances.toString() : null;
                String minErrorParameter = minOccurances != null ? minOccurances.toString() : null;
        
        // If both comparisons happened then if either comparison failed we can show the end user the expected range on both sides.
        if (lessThanMax != Result.UNDEFINED && greaterThanMin != Result.UNDEFINED) 
                return result.addError(attributeValueReader, CONSTRAINT_NAME, RiceKeyConstants.ERROR_QUANTITY_RANGE, minErrorParameter, maxErrorParameter);
        // If it's the max comparison that fails, then just tell the end user what the max can be
        else if (lessThanMax == Result.INVALID)
                return result.addError(attributeValueReader, CONSTRAINT_NAME, RiceKeyConstants.ERROR_MAX_OCCURS, maxErrorParameter);
        // Otherwise, just tell them what the min can be
        else 
                return result.addError(attributeValueReader, CONSTRAINT_NAME, RiceKeyConstants.ERROR_MIN_OCCURS, minErrorParameter);
        
        // Obviously the last else above is unnecessary, since anything after it is dead code, but keeping it seems clearer than dropping it
        }
        
}