class VendingMachine {
    constructor() {
        this.noCoinState = new NoCoinState(this);
        this.hasCoinState = new HasCoinState(this);
        this.currentState = this.noCoinState;
    }
    setState(state) { this.currentState = state; }
    insertCoin() { this.currentState.insertCoin(); }
    pushButton() { this.currentState.pushButton(); }
}

class NoCoinState {
    constructor(machine) { this.machine = machine; }
    insertCoin() {
        console.log("동전을 넣었습니다.");
        this.machine.setState(this.machine.hasCoinState);
    }
    pushButton() { console.log("동전을 먼저 넣어주세요."); }
}

class HasCoinState {
    constructor(machine) { this.machine = machine; }
    insertCoin() { console.log("이미 동전이 있습니다."); }
    pushButton() {
        console.log("음료수가 나옵니다.");
        this.machine.setState(this.machine.noCoinState);
    }
}

const machine = new VendingMachine();
machine.pushButton();
machine.insertCoin();
machine.pushButton();