/**
    * Copyright 2005-2013 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;
  
  import org.kuali.rice.krad.datadictionary.AttributeDefinition;
  import org.kuali.rice.krad.datadictionary.exception.AttributeValidationException;
  import org.kuali.rice.krad.datadictionary.validation.capability.Constrainable;
  import org.kuali.rice.krad.datadictionary.validation.constraint.DataTypeConstraint;
  
  import java.util.List;
  
  /**
   * This class allows a single attribute value to be exposed to the validation service, along
   * with some guidance about how that value should be interpreted, provided by the AttributeDefinition
   * that corresponds. It's a special AttributeValueReader since it explicitly doesn't expose any
   * other attribute values, so it should only be used when the underlying business object is not available
   * and we want to limit access to (for example) validation that requires only a single attribute value.
   * This eliminates more complicated validation like 'this field is required when another field is filled in.'
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class SingleAttributeValueReader extends BaseAttributeValueReader {
  
      private Object value;
      private AttributeDefinition definition;
  
      public SingleAttributeValueReader(Object value, String entryName, String attributeName,
              AttributeDefinition definition) {
          this.value = value;
          this.entryName = entryName;
          this.attributeName = attributeName;
          this.definition = definition;
      }
  
      @Override
      public Constrainable getDefinition(String attributeName) {
          // Only return the definition if you have it, and if it's the definition for the passed attribute name
          return definition != null && definition.getName() != null && definition.getName().equals(attributeName) ?
                  definition : null;
      }
  
      @Override
      public List<Constrainable> getDefinitions() {
          return null;
      }
  
      /**
       * @see org.kuali.rice.krad.datadictionary.validation.AttributeValueReader#getEntry()
       */
      @Override
      public Constrainable getEntry() {
          return null;
      }
  
      @Override
      public String getLabel(String attributeName) {
          if (definition != null && definition.getName() != null && definition.getName().equals(attributeName)) {
              return definition.getLabel();
          }
  
          return attributeName;
      }
  
      @Override
      public Object getObject() {
          return null;
      }
  
      @Override
      public String getPath() {
          return attributeName;
      }
  
      @Override
      public Class<?> getType(String selectedAttributeName) {
          Constrainable attributeDefinition = getDefinition(selectedAttributeName);
  
          if (attributeDefinition != null && attributeDefinition instanceof DataTypeConstraint) {
              DataTypeConstraint dataTypeConstraint = (DataTypeConstraint) attributeDefinition;
              if (dataTypeConstraint.getDataType() != null) {
                  return dataTypeConstraint.getDataType().getType();
              }
          }
  
          // Assuming we can reliably guess
          return value != null ? value.getClass() : null;
     }
 
     @Override
     public boolean isReadable() {
         return true;
     }
 
     @Override
     public <X> X getValue() throws AttributeValidationException {
         return (X) value;
     }
 
     @Override
     public <X> X getValue(String attributeName) throws AttributeValidationException {
         Constrainable attributeDefinition = getDefinition(attributeName);
 
         if (attributeDefinition != null) {
             return (X) value;
         }
 
         return null;
     }
 
     @Override
     public AttributeValueReader clone() {
         SingleAttributeValueReader clone = new SingleAttributeValueReader(this.value, this.entryName,
                 this.attributeName, this.definition);
         clone.setAttributeName(this.attributeName);
         return clone;
     }
 
 }