# -*- mode: nim; Encoding: utf-8; coding: utf-8 -*-
# Last updated: <2017/09/16 00:00:00 +0900>
#
# OpenGLが利用できそうか確認するサンプル
# Google Gemini に作ってもらった
#
# Windows11 x64 25H2 + Nim 2.2.8 64bit

import winim/lean
import opengl
import std/monotimes

# 必要な情報をまとめる構造体
type AppWindow = object
  hwnd: HWND
  hdc: HDC
  hrc: HGLRC

# --- 1. ウィンドウプロシージャ（イベント処理） ---
proc windowProc(
    hwnd: HWND, uMsg: UINT, wParam: WPARAM, lParam: LPARAM
): LRESULT {.stdcall.} =
  case uMsg
  of WM_DESTROY:
    PostQuitMessage(0)
    return 0
  of WM_KEYDOWN:
    if wParam == VK_ESCAPE:
      PostMessage(hwnd, WM_CLOSE, 0, 0)
    return 0
  else:
    return DefWindowProc(hwnd, uMsg, wParam, lParam)

# --- 2. ウィンドウとOpenGLの初期化 ---
proc initWindow(width, height: int): AppWindow =
  let hInstance = GetModuleHandle(nil)
  let className = "NimGLWindow"

  var wc: WNDCLASS
  wc.lpfnWndProc = windowProc
  wc.hInstance = hInstance
  wc.lpszClassName = className
  wc.hCursor = LoadCursor(0, IDC_ARROW)
  RegisterClass(addr wc)

  let hwnd = CreateWindowEx(
    0,
    className,
    "Nim OpenGL - Single EXE Framework",
    WS_OVERLAPPEDWINDOW or WS_VISIBLE,
    CW_USEDEFAULT,
    CW_USEDEFAULT,
    width.int32,
    height.int32,
    0,
    0,
    hInstance,
    nil,
  )

  # OpenGL初期化
  let hdc = GetDC(hwnd)
  var pfd: PIXELFORMATDESCRIPTOR
  pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR).uint16
  pfd.nVersion = 1
  pfd.dwFlags = PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER
  pfd.iPixelType = PFD_TYPE_RGBA
  pfd.cColorBits = 32

  let pixFormat = ChoosePixelFormat(hdc, addr pfd)
  SetPixelFormat(hdc, pixFormat, addr pfd)

  let hrc = wglCreateContext(hdc)
  wglMakeCurrent(hdc, hrc)
  loadExtensions() # モダンな関数を使えるようにロード

  result = AppWindow(hwnd: hwnd, hdc: hdc, hrc: hrc)

# --- 3. 描画ロジック（アスペクト比補正付き） ---
proc render(app: AppWindow, angle: float32) =
  # ウィンドウサイズの取得
  var rect: RECT
  GetClientRect(app.hwnd, addr rect)
  let w = (rect.right - rect.left).float32
  let h = (rect.bottom - rect.top).float32

  # ビューポートと投影行列の設定（引き伸ばし防止）
  glViewport(0, 0, w.int32, h.int32)
  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()

  let aspect =
    if h != 0:
      w / h
    else:
      1.0
  if w >= h:
    glOrtho(-aspect, aspect, -1.0, 1.0, -1.0, 1.0)
  else:
    glOrtho(-1.0, 1.0, -1.0 / aspect, 1.0 / aspect, -1.0, 1.0)

  # モデルビュー行列のリセットと描画
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()

  glClearColor(0.1, 0.2, 0.3, 1.0)
  glClear(GL_COLOR_BUFFER_BIT)

  # 回転の適用
  glRotatef(angle, 0, 0, 1)

  # 三角形の描画
  glBegin(GL_TRIANGLES)
  glColor3f(1.0, 0.0, 0.0)
  glVertex2f(0.0, 0.8)
  glColor3f(0.0, 1.0, 0.0)
  glVertex2f(-0.8, -0.8)
  glColor3f(0.0, 0.0, 1.0)
  glVertex2f(0.8, -0.8)
  glEnd()

# --- 4. メインループ ---
proc mainLoop(app: AppWindow) =
  var msg: MSG
  var angle: float32 = 0.0
  let rotationSpeed: float32 = 90.0 # 1秒間に90度

  var lastTicks = getMonoTime().ticks

  while true:
    if PeekMessage(addr msg, 0, 0, 0, PM_REMOVE) != 0:
      if msg.message == WM_QUIT:
        break
      TranslateMessage(addr msg)
      DispatchMessage(addr msg)
    else:
      # デルタタイム計算 (.ticks を使用)
      let currentTicks = getMonoTime().ticks
      let dt = (currentTicks - lastTicks).float32 / 1_000_000_000.0
      lastTicks = currentTicks

      angle += rotationSpeed * dt
      # if angle > 360.0:
      #   angle -= 360.0

      render(app, angle)
      SwapBuffers(app.hdc)
      Sleep(15)

# --- 5. メイン ---
proc main() =
  let app = initWindow(800, 600)

  # 使用中のOpenGLのバージョンを表示
  # echo "Vendor:   ", $glGetString(GL_VENDOR)
  # echo "Renderer: ", $glGetString(GL_RENDERER)
  # echo "Version:  ", $glGetString(GL_VERSION)

  mainLoop(app)

main()