discountCalculatorFactory.ts

export class DiscountCalculatorFactory {
    static for(numberOfSameBook: number): DiscountCalculator {
        switch (numberOfSameBook) {
            case 1:
                return new NoDiscountCalculator()
            case 2:
                return new TwoSameBooksDiscountCalculator()
            default:
                return new ThreeOrMoreSameBooksDiscountCalculator()
        }
    }
}