> For the complete documentation index, see [llms.txt](https://seunghyun-kim-1.gitbook.io/my-knowledge-library/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://seunghyun-kim-1.gitbook.io/my-knowledge-library/jetbrains-academy/kotlin-basics/coffee-machine/keep-track-of-the-supplies/work-on-project.md). # Work on project **Description** Just one action is not so interesting, is it? Let's improve the program so it can do multiple actions, one after another. It should repeatedly ask a user what they want to do. If the user types `"buy"`, `"fill"` or `"take"`, then the program should do exactly the same thing it did in the previous step. However, if the user wants to switch off the coffee machine, they should type `"exit"`. The program should terminate on this command. Also, when the user types `"remaining"`, the program should output all the resources that the coffee machine has. This means that you shouldn't show the remaining stock levels at the beginning/end of the program. Remember, that: * For the espresso, the coffee machine needs 250 ml of water and 16 g of coffee beans. It costs $4. * For the latte, the coffee machine needs 350 ml of water, 75 ml of milk, and 20 g of coffee beans. It costs $7. * And for the cappuccino, the coffee machine needs 200 ml of water, 100 ml of milk, and 12 g of coffee. It costs $6. **Objectives** Write a program that will work endlessly to make coffee for all interested persons until the shutdown signal is given. Introduce two new options: `"remaining"` and `"exit"`. Do not forget that you can be out of resources for making coffee. If the coffee machine doesn't have enough resources to make coffee, the program should output a message that says it can't make a cup of coffee and state what is missing. And the last improvement to the program at this step — if the user types `"buy"` to buy a cup of coffee and then changes his mind, they should be able to type `"back"` to return into the main cycle. **Example** Your coffee machine should have the same initial resources as in the example (*400 ml* of water, *540 ml* of milk, *120 g* of coffee beans, *9* disposable cups, *$550* in cash). The greater-than symbol followed by a space (`>` ) represents the user input. Note that it's not part of the input. ``` Write action (buy, fill, take, remaining, exit): > remaining The coffee machine has: 400 ml of water 540 ml of milk 120 g of coffee beans 9 disposable cups $550 of money Write action (buy, fill, take, remaining, exit): > buy What do you want to buy? 1 - espresso, 2 - latte, 3 - cappuccino, back - to main menu: > 2 I have enough resources, making you a coffee! Write action (buy, fill, take, remaining, exit): > remaining The coffee machine has: 50 ml of water 465 ml of milk 100 g of coffee beans 8 disposable cups $557 of money Write action (buy, fill, take, remaining, exit): > buy What do you want to buy? 1 - espresso, 2 - latte, 3 - cappuccino, back - to main menu: > 2 Sorry, not enough water! Write action (buy, fill, take, remaining, exit): > fill Write how many ml of water you want to add: > 1000 Write how many ml of milk you want to add: > 0 Write how many grams of coffee beans you want to add: > 0 Write how many disposable cups you want to add: > 0 Write action (buy, fill, take, remaining, exit): > remaining The coffee machine has: 1050 ml of water 465 ml of milk 100 g of coffee beans 8 disposable cups $557 of money Write action (buy, fill, take, remaining, exit): > buy What do you want to buy? 1 - espresso, 2 - latte, 3 - cappuccino, back - to main menu: > 2 I have enough resources, making you a coffee! Write action (buy, fill, take, remaining, exit): > remaining The coffee machine has: 700 ml of water 390 ml of milk 80 g of coffee beans 7 disposable cups $564 of money Write action (buy, fill, take, remaining, exit): > take I gave you $564 Write action (buy, fill, take, remaining, exit): > remaining The coffee machine has: 700 ml of water 390 ml of milk 80 g of coffee beans 7 disposable cups $0 of money Write action (buy, fill, take, remaining, exit): > exit ``` mycode: ```kotlin const val WELCOME_MESSAGE = "Write action (buy, fill, take, remaining, exit):" fun main() { var hasWater: Int = 400 var hasMilk: Int = 540 var hasBeans: Int = 120 var hasCups: Int = 9 var hasMoney: Int = 550 var system = "" while (system != "exit") { println(WELCOME_MESSAGE) var user = readln() println() when (user) { "remaining" -> { val hasMaterial = """ The coffee machine has: $hasWater ml of water $hasMilk ml of milk $hasBeans g of coffee beans $hasCups disposable cups $hasMoney of money """.trimIndent() println("$hasMaterial\n") } "exit" -> system = "exit" "buy" -> { while (true) { println("what do you want to buy? 1 - espresso, 2 - latte, 3 - cappuccino, back - to main menu:") val buyMenu = readln() if (buyMenu == "back") break else buyMenu.toInt() when (buyMenu) { "1" -> { if (hasWater < 250) { println("Sorry, not enough water!\n") break } else { println("I have enough resources, making you a coffee!\n") hasWater -= 250 hasBeans -= 16 hasCups -= 1 hasMoney += 4 break } } "2" -> { if (hasWater < 350) { println("Sorry, not enough water!\n") break } else { println("I have enough resources, making you a coffee!\n") hasWater -= 350 hasMilk -= 75 hasBeans -= 20 hasCups -= 1 hasMoney += 7 break } } "3" -> { if (hasWater < 200) { println("Sorry, not enough water!\n") break } else { println("I have enough resources, making you a coffee!\n") hasWater -= 200 hasMilk -= 100 hasBeans -= 12 hasCups -= 1 hasMoney += 6 break } } } } } "fill" -> { println("Write how many ml of water you want to add:") val fillWater = readln().toInt() println("Write how many ml of milk you want to add:") val fillMilk = readln().toInt() println("Write how many grams of coffee beans you want to add:") val fillBeans = readln().toInt() println("Write how many disposable cups you want to add:") val fillCups = readln().toInt() hasWater += fillWater hasMilk += fillMilk hasBeans += fillBeans hasCups += fillCups } "take" -> { println("I gave you $hasMoney") hasMoney -= hasMoney } } } } ```