(ns age-of-sail.simulation)

(def tickrate 100)
(def hooks (atom '()))
(defn subscribe!
  "Adds a hook to the hooks"
  [f]
  (swap! hooks conj f))

(defonce program (atom :stopped))

(defn game-loop
  []
  (while (#{:running :paused} @program)
    (when (= :running @program)
      (doseq [hook @hooks]
        (hook)))
    (Thread/sleep (quot 1000 tickrate)))
  (when-not (compare-and-set! program :killed :stopped)
    (throw "Error: tried to stop a program that wasn't killed!")))

(defn pause-program
  []
  (compare-and-set! program :running :paused))

(defn kill-program
  []
  (compare-and-set! program :running :paused)
  (compare-and-set! program :paused :killed))

(defn start-program
  []
  (when (= (first (reset-vals! program :running)) :stopped)
    (.start (Thread. game-loop))))