package org.kuali.common.util.validate;
   
   import java.lang.reflect.Field;
   import java.util.Collection;
   import java.util.Map;
   
   import org.kuali.common.util.CollectionUtils;
   import org.kuali.common.util.ReflectionUtils;
   
  import com.google.common.base.Optional;
  
  public class NoBlankMapKeysValidator extends AbstractFieldsValidator<NoBlankMapKeys, Object> {
  
  	@Override
  	protected Optional<String> validate(Field field, Object instance) {
  
  		// This field may not be a Map<String,?>
  		if (!ReflectionUtils.isStringKeyedMap(field)) {
  			return Optional.absent();
  		}
  
  		// Extract the value of the field into an optional
  		Optional<?> fieldValue = ReflectionUtils.get(field, instance);
  
  		// If there is no value for this field, we are done
  		if (!fieldValue.isPresent()) {
  			return Optional.absent();
  		}
  
  		// We know the field is a map that uses strings for it's keys at this point
  		@SuppressWarnings("unchecked")
  		Map<String, ?> map = (Map<String, ?>) fieldValue.get();
  
  		// Extract any entries with a blank key
  		Collection<String> blanks = CollectionUtils.getBlanks(map.keySet());
  		if (blanks.size() > 0) {
  			return Validation.errorMessage(field, "contains " + blanks.size() + " blank keys");
  		} else {
  			return Optional.absent();
  		}
  	}
  }