/**
    * 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;
  
  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 <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;
 	}
 
 }