#lang racket/base

(require ffi/unsafe
         ffi/unsafe/define)

(define-ffi-definer define-user32 (ffi-lib "user32"))
(define-ffi-definer define-kernel32 (ffi-lib "kernel32"))

(define _WindowClassStyles
  (_bitmask
   '(CS_VREDRAW          = #x0001
     CS_HREDRAW          = #x0002
     CS_OWNDC            = #x0020)))

(define _ExtendedWindowStyles
  (_bitmask
   '(WS_VSCROLL              = #x10000000
     WS_EX_CLIENTEDGE        = #x00000200
     WS_EX_WINDOWEDGE        = #x00000100)))

(define CW_USEDEFAULT #x80000000)

(define-cpointer-type _WNDPROC)
(define-cpointer-type _HANDLE)
(define-cpointer-type _HICON)
(define-cpointer-type _HCURSOR)
(define-cpointer-type _HBRUSH)
(define-cpointer-type _LPCSTR)
(define-cpointer-type _HMENU)
(define-cpointer-type _LPVOID)

(define-cstruct _WNDCLASSEXA ([cbSize _uint32]
                              [style _WindowClassStyles]
                              [lpfnWndProc _WNDPROC/null]
                              [cbClsExtra _uint32]
                              [cbWndExtra _uint32]
                              [hInstance _HANDLE/null]
                              [hIcon _HICON/null]
                              [hCursor _HCURSOR/null]
                              [hbrBackground _HBRUSH/null]
                              [lpszMenuName _string/utf-8]
                              [lpszClassName _string/utf-8]
                              [hIconSm _HICON/null]))

(define-kernel32 GetModuleHandleA (_fun _pointer -> _HANDLE/null))

(define-user32 RegisterClassExA (_fun _WNDCLASSEXA-pointer -> _ushort))

(define WindowClass
  (make-WNDCLASSEXA
   (ctype-sizeof _WNDCLASSEXA)
   '(CS_HREDRAW CS_VREDRAW CS_OWNDC)
   #f
   0
   0
   (GetModuleHandleA #f)
   #f
   #f
   #f
   #f
   "HandmadeHeroWindowClass"
   #f))

(RegisterClassExA WindowClass)

(define-user32 CreateWindowExA (_fun
                                _uint32 ;; dwExStyle
                                _string/utf-8 ;; lpClassName
                                _string/utf-8 ;; lpWindowName
                                _ExtendedWindowStyles ;; dwStyle
                                _uint32 ;; X
                                _uint32 ;; Y
                                _uint32 ;; nWidth
                                _uint32 ;; nHeight
                                _HANDLE/null ;; hWndParent
                                _HMENU/null ;; hMenu
                                _HANDLE/null ;; hInstance
                                _LPVOID/null ;; lpParam
                                -> _HANDLE))

(CreateWindowExA
 0
 (WNDCLASSEXA-lpszClassName WindowClass)
 "Handmade Hero in Racket"
 '(WS_EX_WINDOWEDGE WS_EX_CLIENTEDGE WS_VSCROLL)
 CW_USEDEFAULT
 CW_USEDEFAULT
 CW_USEDEFAULT
 CW_USEDEFAULT
 #f
 #f
 (GetModuleHandleA #f)
 #f)