/*
实例：
汤宝宝成为了收银员，消费者可以使用现金或者支付宝支付。
*/

interface Strategy {
    pay(amount: number): string;
    }

class CashStrategy implements Strategy {
    pay(amount: number): string {
        return `使用现金支付了${amount.toFixed(2)}元`;
    }
}

class AlipayStrategy implements Strategy {
    pay(amount: number): string {
        return `使用支付宝支付了${amount.toFixed(2)}元`;
    }
}

class Context {
    private strategy: Strategy| null = null;

    setStrategy(strategy: Strategy) {
        this.strategy = strategy;
    }

    pay(amount: number): string {
        if (!this.strategy) {
            throw new Error("支付策略未设置");
        }
        return this.strategy.pay(amount);
    }
}

(function(){
    console.log("=========== 策略模式 ===========")
    const context = new Context();

    context.setStrategy(new CashStrategy());
    console.log(context.pay(100));

    context.setStrategy(new AlipayStrategy());
    console.log(context.pay(200));

    console.log("\n========= 策略模式结束 =========")
})()