require 'green_shoes'

Shoes.app(title: "My calculator", width: 200, height: 240) do
	number_field = nil
	@number = 0
	@op = nil
	@previous = 0

	flow width: 200, height: 240 do
		flow width: 0.7, height: 0.2 do
			background rgb(0, 157, 228)
			number_field = para @number, margin: 10
		end

		flow width: 0.3, height: 0.2 do
			button 'Clr', width: 1.0, height: 1.0 do
				@number = 0
				number_field.replace(@number)
			end
		end

		flow width: 1.0, height: 0.8 do
			background rgb(139, 206, 236)
			%w(7 8 9 + 4 5 6 - 1 2 3 / 0 . = *).each do |btn|
				button btn, width: 50, height: 50 do
					case btn
						when /[0-9]/
							@number = @number.to_i * 10 + btn.to_i
						when '='
							@number = @previous.send(@op, @number)
						else
							@previous, @number = @number, nil
							@op = btn
					end
					number_field.replace(@number)
				end
			end
		end
	end
end