#lang racket/base

(require data/heap)

(provide

(all-defined-out))

(define (make-renderer sdl-renderer)

(define make-render-queue-item cons)

(define render-queue-item-order car)

(define render-queue-item-proc cdr)

(define (render-queue-item-comparator x y)

(<= (render-queue-item-order x) (render-queue-item-order y)))

(define render-queue (make-heap render-queue-item-comparator))

(define (render order render-proc)

(heap-add! render-queue (make-render-queue-item order render-proc)))

(define (do-draw)

(for ([item (in-heap/consume! render-queue)])

((render-queue-item-proc item) sdl-renderer)))

(lambda (msg)

(case msg

[(render) render]

[(do-draw) do-draw]

[else (error 'renderer "Unknown message: ~a" msg)])))

(define (renderer-render r o p)

((r 'render) o p))

(define (renderer-do-draw r)

((r 'do-draw)))