21 Sticks

class MyApp extends App{
	
	numberOfSticksLeft = 21
	
	take3Sticks(){
		a.numberOfSticksLeft -= 3
	}
	
	take2Sticks(){
		a.numberOfSticksLeft -= 2
	}
	
	take1Stick(){
		a.numberOfSticksLeft -= 1
	}
	
	createStartPage(){
		return AskUserToMakeAMove
	}
	
}

class AskUserToMakeAMove extends Page{
	
	createGui(){
		
		return Rows.children(
			Space,
			Text.text(`There are ${a.numberOfSticksLeft} sticks left.`),
			Space,
			Text.text(`How many sticks do you want to take?`),
			Columns.children(
				Space,
				Button.text(`1 sticks`).handler(a.take1Stick),
				Space,
				Button.keepIf(2 <= a.numberOfSticksLeft).text(`2 sticks`).handler(a.take2Sticks),
				Space.keepIf(2 <= a.numberOfSticksLeft),
				Button.keepIf(3 <= a.numberOfSticksLeft).text(`3 sticks`).handler(a.take3Sticks),
				Space.keepIf(3 <= a.numberOfSticksLeft),
			),
			Space,
		)
		
	}
	
	createAfterDirections(){
		
		return [
			Direction.page(ComputerWon).when(a.numberOfSticksLeft == 0).text(`The computer won`),
			Direction.page(ShowGameAfterUserMove).when(true).text(`Game not finished`),
		]
		
	}
	
}

class ShowGameAfterUserMove extends Page{
	
	createGui(){
		return Rows.children(
			Space,
			Text.text(`There are ${a.numberOfSticksLeft} sticks left.`),
			Space,
			Columns.children(
				Space,
				Button.text(`The computer's turn...`).page(ShowGameAfterComputerMove),
				Space,
			),
			Space,
		)
		
	}
	
}

class ShowGameAfterComputerMove extends Page{
	
	numberOfSticksTheComputerTakes = 0
	
	onBefore(){
		
		// Compute how many sticks the computer may take.
		const maxSticksToTake = m.lowest(3, a.numberOfSticksLeft)
		
		// Then the computer will get a random number of sticks.
		p.numberOfSticksTheComputerTakes = m.randomInt(1, maxSticksToTake)
		
		a.numberOfSticksLeft -= p.numberOfSticksTheComputerTakes
		
	}
	
	createGui(){
		return Rows.children(
			Space,
			Text.text(`The computer takes ${p.numberOfSticksTheComputerTakes} sticks.`),
			Space,
			Text.text(`Now there are ${a.numberOfSticksLeft} sticks left.`),
			Space,
			Button.text(`OK`),
			Space,
		)
	}
	
	createAfterDirections(){
		
		return [
			Direction.page(PlayerWon).when(a.numberOfSticksLeft == 0).text(`The player won`),
			Direction.page(AskUserToMakeAMove).when(true).text(`Game not finished`),
		]
		
	}
	
}

class ComputerWon extends Page{
	createGui(){
		return Rows.children(
			Space,
			Text.text(`Too bad, the computer won ☹️`),
			Space,
		)
	}
}

class PlayerWon extends Page{
	createGui(){
		return Rows.children(
			Space,
			Text.text(`Congratulation, you won! 😊`),
			Space,
		)
	}
}