001package scpc.model;
002
003import javax.script.ScriptException;
004
005/**
006 * Promotion rule that result in bonus item.
007 * <br>定義優惠的規則
008 *
009 * @author Kent Yeh
010 * @param <T> type of real cart item.
011 */
012public interface ILeafRule<T> extends IRule<T> {
013
014    /**
015     * 優惠品項.
016     *
017     * @return Instance of Bonus.
018     */
019    public IItem<T> getBonus();
020
021    /**
022     * Current visit item is bonus item.
023     * <br>優惠品項就是當下走訪的品項
024     *
025     * @param item current visit item.
026     * @return Clone item when returning bonus is current visit item.
027     */
028    public IItem<T> getCurrentAsBonus(IItem<T> item);
029
030    /**
031     * Quantity measure of bonus after {@link IRule#isTriggered(scpc.model.SingleItem)
032     * }.
033     * <br> 觸發觸發後，優惠品項的數量估值
034     *
035     * @return evulate quantity of bonus
036     * @throws ScriptException Error prone when quantity measure meet an error.
037     */
038    public double evalQuantity() throws ScriptException;
039
040    /**
041     * Only the last measure set to quantity.<br>
042     * <br>只承認最後一次的數量估值
043     *
044     * @return whether the last measure set to quantity.
045     */
046    public boolean isLastQuantityOnly();
047
048}