Coffee.kt

interface Coffee {
    fun cost(): Double
    fun ingredients(): String
}

class Espresso : Coffee {
    override fun cost() = 2.0

    override fun ingredients() = "Espresso"
}

abstract class CoffeeDecorator(private val coffee: Coffee) : Coffee {
    override fun cost() = coffee.cost()
    override fun ingredients() = coffee.ingredients()
}

class MilkDecorator(coffee: Coffee) : CoffeeDecorator(coffee) {
    override fun cost() = super.cost() + 0.5
    override fun ingredients() = "${super.ingredients()} + Milk"
}

class SugarDecorator(coffee: Coffee) : CoffeeDecorator(coffee) {
    override fun cost() = super.cost() + 0.3
    override fun ingredients() = "${super.ingredients()} + Sugar"
}

val coffee = Espresso()
println("Coffee: ${coffee.ingredients()} - Cost: ${coffee.cost()}")

val coffeeWithMilk = MilkDecorator(coffee)
println("Coffee with Milk: ${coffeeWithMilk.ingredients()} - Cost: ${coffeeWithMilk.cost()}")

val coffeeWithMilkAndSugar = SugarDecorator(coffeeWithMilk)
println("Coffee with Milk and Sugar: ${coffeeWithMilkAndSugar.ingredients()} - Cost: ${coffeeWithMilkAndSugar.cost()}")