feat: implement game-run! — SDL2 init, lifecycle hooks, frame loop

2 files changed, 67 insertions, 3 deletions

diff --git a/engine.scm b/engine.scm
index f6c9db7..73e88f0 100644
--- a/engine.scm
+++ b/engine.scm
@@ -71,9 +71,69 @@
   (asset-set! (game-assets game) key value))
 
 ;; ── game-run! ──────────────────────────────────────────────────────────────
-;; Stub — implemented in Task 4
+;; Main event loop and lifecycle orchestration
 
 (define (game-run! game)
-  (error "game-run! not yet implemented"))
+  ;; 1. SDL2 init (audio excluded — mixer.scm not yet extracted;
+  ;;    user calls init-audio! in their preload: hook)
+  (sdl2:set-main-ready!)
+  (sdl2:init! '(video joystick game-controller))
+  (ttf:init!)
+  (img:init! '(png))
+
+  ;; Open any already-connected game controllers
+  (let init-controllers ((i 0))
+    (when (< i (sdl2:num-joysticks))
+      (when (sdl2:is-game-controller? i)
+        (sdl2:game-controller-open! i))
+      (init-controllers (+ i 1))))
+
+  ;; 2. Create window + renderer
+  (game-window-set! game
+    (sdl2:create-window! (game-title game) 'centered 'centered
+                         (game-width game) (game-height game) '()))
+  (game-renderer-set! game
+    (sdl2:create-renderer! (game-window game) -1 '(accelerated vsync)))
+
+  ;; 3. preload: hook — user loads assets here
+  (when (game-preload-hook game)
+    ((game-preload-hook game) game))
+
+  ;; 4. create: hook — user builds initial scene here
+  (when (game-create-hook game)
+    ((game-create-hook game) game))
+
+  ;; 5. Frame loop
+  (let loop ((last-ticks (sdl2:get-ticks)))
+    (let* ((now    (sdl2:get-ticks))
+           (dt     (- now last-ticks)))
+      ;; Collect all pending SDL2 events
+      (sdl2:pump-events!)
+      (let* ((events (let collect ((lst '()))
+                       (if (not (sdl2:has-events?))
+                           (reverse lst)
+                           (let ((e (sdl2:make-event)))
+                             (sdl2:poll-event! e)
+                             (collect (cons e lst))))))
+             (input  (input-state-update (game-input game) events
+                                         (game-input-config game))))
+        (game-input-set! game input)
+        (unless (input-held? input 'quit)
+          ;; update: hook — user game logic
+          (when (game-update-hook game)
+            ((game-update-hook game) game dt))
+          ;; render: engine draws world, then user overlay
+          (sdl2:render-clear! (game-renderer game))
+          (when (game-scene game)
+            (render-scene! (game-renderer game) (game-scene game)))
+          (when (game-render-hook game)
+            ((game-render-hook game) game))
+          (sdl2:render-present! (game-renderer game))
+          (sdl2:delay! (game-frame-delay game))
+          (loop now)))))
+
+  ;; 6. Cleanup
+  (sdl2:destroy-window! (game-window game))
+  (sdl2:quit!))
 
 ) ;; end module
diff --git a/tests/engine-test.scm b/tests/engine-test.scm
index b026ce4..2c443cc 100644
--- a/tests/engine-test.scm
+++ b/tests/engine-test.scm
@@ -64,7 +64,11 @@
       controller-axis-bindings: '((left-x right left) (left-y down up))
       deadzone: 8000))
   (define (create-input-state config)
-    (make-input-state '() '())))
+    (make-input-state '() '()))
+  (define (input-state-update state events config)
+    state)
+  (define (input-held? state action)
+    #f))
 (import downstroke/input)
 
 ;; --- World module (mock) ---