package org.opengroupware.jope.foundation;

public interface NSValidation {
  
  public Object validateValueForKey(Object _value, String _key)
    throws ValidationException;
  
  /* utility class (use those methods to query objects with KVC) */

  public class Utility {
    
    public Object validateValueForKey(Object _o, Object _value, String _key) 
      throws ValidationException
    {
      if (_o == null)
        return null;
      
      if (_o instanceof NSValidation)
        return ((NSValidation)_o).validateValueForKey(_value, _key);
      
      return NSValidation.DefaultImplementation
        .validateValueForKey(_o, _value, _key);
    }
  }

  /* this can be used by Object subclasses which want to implement
   * NSValidation
   */
  public class DefaultImplementation {
    
    public static Object validateValueForKey(Object _o, Object _v, String _key) 
      throws ValidationException
    {
      if (_o == null)
        return null;
      
      // TODO: implement me (call validate<KEY>())
      
      return _v;
    }
    
  }
  
  /* exception class */

  public static class ValidationException extends NSException {
    private static final long serialVersionUID = 1L;
    
    public ValidationException() {
      super("validation failed");
    }
    public ValidationException(String _reason) {
      super(_reason);
    }
  }
}