package bjc.utils.dice;

/**
 * A dice expression that combines a scalar and a dice
 * 
 * @author ben
 *
 */
public class ScalarDiceExpression implements IDiceExpression {
	/**
	 * The operation to combine with
	 */
	private DiceExpressionType	det;
	/**
	 * The expression to be combined
	 */
	private IDiceExpression		exp;

	/**
	 * The scalar to be combined
	 */
	private int					scalar;

	/**
	 * Create a dice expression with a scalar
	 * @param dex The dice to use
	 * @param scalr The scalar to use
	 * @param dt The operation to combine with
	 */
	public ScalarDiceExpression(IDiceExpression dex, int scalr,
			DiceExpressionType dt) {
		exp = dex;
		scalar = scalr;
		det = dt;
	}

	@Override
	public int roll() {
		switch (det) {
			case ADD:
				return exp.roll() + scalar;
			case SUBTRACT:
				return exp.roll() - scalar;
			case MULTIPLY:
				return exp.roll() * scalar;
			case DIVIDE:
				return Math.round(exp.roll() / scalar);
			default:
				throw new IllegalStateException(
						"Got passed  a invalid ScalarExpressionType "
								+ det);
		}
	}
}