package Calculator;

public class OpButtonObj extends ButtonObj 
{
  public static final OpButtonObj NO_OP_BUTTON_OBJ
                                     = new OpButtonObj( Calculator.NO_OP );

  private int       buttonOp;
  private ButtonObj equalButton;

  private OpButtonObj( int buttonID ) 
  {
    super( null, null );
    this.buttonOp = buttonID;
  }

  public OpButtonObj( int op,
		      ButtonObj equalButton,
		      CalcTextGUI gui,
		      CalculatorState stateObj ) 
  {
    super( gui, stateObj );
    this.buttonOp = op;
    this.equalButton = equalButton;
  }

  public void handleButton() 
  {
    this.stateObj.doneReadingNumber();

    if ( this.stateObj.getPendingOperation() != OpButtonObj.NO_OP_BUTTON_OBJ ) 
    {
      this.equalButton.handleButton();
    } else {
      this.stateObj.setPreviousOperand( this.gui.getValue() );
    }
    this.stateObj.setPendingOperation( this );
  }

  public double doOperation ( double leftOperand, double rightOperand ) 
  {
	switch ( this.buttonOp ) 
	{
	    case Calculator.OP_MUL:
		return ( leftOperand * rightOperand );
	    case Calculator.OP_DIV:
		return ( leftOperand / rightOperand );
	    case Calculator.OP_SUB:
		return ( leftOperand - rightOperand );
	    case Calculator.OP_ADD:
		return ( leftOperand + rightOperand );
	    case Calculator.NO_OP:
		// fall through....
	    default:
		return ( rightOperand );
	}
  }

}