(local (w h) (love.window.getMode))

(local keys {:a [:left -1] :z [:left 1] :up [:right -1] :down [:right 1]})

(global Pong {})
(set Pong.__index Pong)

(fn Pong.init [cls]
  (let [t {:x 100 :y 100
           :dx 2 :dy 1
           :left (- (/ h 2) 50) :right (- (/ h 2) 50)
           :speed 1 :ball-speed 200
           :pause false}]
    (setmetatable t cls)))

(fn Pong.on-paddle? [self]
  (or (and (< self.x 20)
           (< self.left self.y) (< self.y (+ self.left 100)))
      (and (< (- w 20) self.x)
           (< self.right self.y) (< self.y (+ self.right 100)))))

(fn Pong.update [self dt set-mode]
  (when (not self.pause)
    (set self.x (+ self.x (* self.dx dt self.ball-speed)))
    (set self.y (+ self.y (* self.dy dt self.ball-speed)))
    (each [key action (pairs keys)]
      (let [[player dir] action]
        (when (love.keyboard.isDown key)
          (tset self player (+ (. self player) (* dir self.speed))))))

    (when (or
           (< self.y 0)
           (> self.y h))
      (set self.dy (- 0 self.dy)))

    (when (: self :on-paddle?)
      (set self.dx (- 0 self.dx)))

    (when (< self.x 0)
      (set-mode "mode.end" "2"))
    (when (> self.x w)
      (set-mode "mode.end" "1"))))

(fn Pong.keypressed [self key set-mode]
  (when (= "p" key)
    (set self.pause (not self.pause))))

(fn Pong.draw [self m]
  (when (not self.pause)
    (love.graphics.rectangle "fill" 10 self.left 10 100)
    (love.graphics.rectangle "fill" (- w 20) self.right 10 100)
    (love.graphics.circle "fill" self.x self.y 10))
  (when self.pause
    (love.graphics.printf "Press 'p' to unpause" 0 (/ h 3) w "center")))

Pong