(ns lab.collisions
  [:require [quil.core :refer :all]
            [quil.middleware :as m]])

(def quant 7)
(def the-w 600)
(def the-h 400)
(def margin-l (+ 0 50))
(def margin-r (- the-w 50))
(def margin-u (+ 0 50))
(def margin-d (- the-h 50))

(defn rand-lower-upper [lower upper]
  (+ lower (rand (- upper lower))))

(defn generate-sprite []
  (hash-map
    :x (rand-lower-upper margin-l margin-r)
    :y (rand-lower-upper margin-u margin-d)
    :dx (rand-lower-upper -1.0 1.0)
    :dy (rand-lower-upper -1.0 1.0)
    :r (rand-int 256)
    :g (rand-int 256)
    :b (rand-int 256)
    :v (rand 4)))

(defn setup []
  (frame-rate 60)
  (take quant (repeatedly generate-sprite)))

(defn move [{:keys [dx dy v] :as sprite}]
  (-> sprite
      (update-in [:x] + (* v dx))
      (update-in [:y] + (* v dy))))

(defn bounce [{:keys [x y dx dy] :as sprite}]
  (let [fx (if (or (and (< x margin-l) (neg? dx))
                   (and (> x margin-r) (pos? dx))) -1 1)
        fy (if (or (and (< y margin-u) (neg? dy))
                   (and (> y margin-d) (pos? dy))) -1 1)]
    (-> sprite
        (update-in [:dx] * fx)
        (update-in [:dy] * fy))))

; alternate behavior to bounce : when sprite touches wall, it disappears and appears in the other side
(defn pass [{:keys [x y dx dy] :as sprite}]
  (let [mrgn-l (if (and (< x margin-l) (neg? dx)) (assoc sprite :x margin-r) sprite)
        mrgn-r (if (and (> x margin-r) (pos? dx)) (assoc mrgn-l :x margin-l) mrgn-l)
        mrgn-u (if (and (< y margin-u) (neg? dy)) (assoc mrgn-r :y margin-d) mrgn-r)
        mrgn-d (if (and (> y margin-d) (pos? dy)) (assoc mrgn-u :y margin-u) mrgn-u)]
    mrgn-d))

(defn my-update [state]
  (map (comp move bounce) state))

(defn draw-sprite [{:keys [x y r g b]}]
  (fill r g b)
  (rect (- x 15) (- y 15) 30 30))

(defn draw [state]
  (background 200 150 255)
  (dorun (map draw-sprite state)))

(defsketch collision
           :title "Colisões"
           :size [the-w the-h]
           :setup setup
           :draw draw
           :update my-update
           :middleware [m/fun-mode])