/*
  Copyright 2012-2020 David Robillard <d@drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "stub.h"
#include "types.h"
#include "win.h"

#include "pugl/gl.h"

#include <windows.h>

#include <GL/gl.h>

#include <stdbool.h>
#include <stdlib.h>

#define WGL_DRAW_TO_WINDOW_ARB 0x2001
#define WGL_ACCELERATION_ARB 0x2003
#define WGL_SUPPORT_OPENGL_ARB 0x2010
#define WGL_DOUBLE_BUFFER_ARB 0x2011
#define WGL_PIXEL_TYPE_ARB 0x2013
#define WGL_RED_BITS_ARB 0x2015
#define WGL_GREEN_BITS_ARB 0x2017
#define WGL_BLUE_BITS_ARB 0x2019
#define WGL_ALPHA_BITS_ARB 0x201b
#define WGL_DEPTH_BITS_ARB 0x2022
#define WGL_STENCIL_BITS_ARB 0x2023
#define WGL_FULL_ACCELERATION_ARB 0x2027
#define WGL_TYPE_RGBA_ARB 0x202b
#define WGL_SAMPLE_BUFFERS_ARB 0x2041
#define WGL_SAMPLES_ARB 0x2042

#define WGL_CONTEXT_MAJOR_VERSION_ARB 0x2091
#define WGL_CONTEXT_MINOR_VERSION_ARB 0x2092
#define WGL_CONTEXT_FLAGS_ARB 0x2094
#define WGL_CONTEXT_PROFILE_MASK_ARB 0x9126

#define WGL_CONTEXT_CORE_PROFILE_BIT_ARB 0x00000001
#define WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB 0x00000002
#define WGL_CONTEXT_DEBUG_BIT_ARB 0x00000001

typedef HGLRC(WINAPI* WglCreateContextAttribs)(HDC, HGLRC, const int*);

typedef BOOL(WINAPI* WglSwapInterval)(int);

typedef BOOL(WINAPI* WglChoosePixelFormat)(HDC,
                                           const int*,
                                           const FLOAT*,
                                           UINT,
                                           int*,
                                           UINT*);

typedef struct {
  WglChoosePixelFormat    wglChoosePixelFormat;
  WglCreateContextAttribs wglCreateContextAttribs;
  WglSwapInterval         wglSwapInterval;
} PuglWinGlProcs;

typedef struct {
  PuglWinGlProcs procs;
  HGLRC          hglrc;
} PuglWinGlSurface;

// Struct to manage the fake window used during configuration
typedef struct {
  HWND hwnd;
  HDC  hdc;
} PuglFakeWindow;

static PuglStatus
puglWinError(PuglFakeWindow* fakeWin, const PuglStatus status)
{
  if (fakeWin->hwnd) {
    ReleaseDC(fakeWin->hwnd, fakeWin->hdc);
    DestroyWindow(fakeWin->hwnd);
  }

  return status;
}

static PuglWinGlProcs
puglWinGlGetProcs(void)
{
  const PuglWinGlProcs procs = {
    (WglChoosePixelFormat)(wglGetProcAddress("wglChoosePixelFormatARB")),
    (WglCreateContextAttribs)(wglGetProcAddress("wglCreateContextAttribsARB")),
    (WglSwapInterval)(wglGetProcAddress("wglSwapIntervalEXT"))};

  return procs;
}

static PuglStatus
puglWinGlConfigure(PuglView* view)
{
  PuglInternals* impl = view->impl;

  // Set attributes to default if they are unset
  // (There is no GLX_DONT_CARE equivalent on Windows)
  if (view->hints[PUGL_DEPTH_BITS] == PUGL_DONT_CARE) {
    view->hints[PUGL_DEPTH_BITS] = 0;
  }
  if (view->hints[PUGL_STENCIL_BITS] == PUGL_DONT_CARE) {
    view->hints[PUGL_STENCIL_BITS] = 0;
  }
  if (view->hints[PUGL_SAMPLES] == PUGL_DONT_CARE) {
    view->hints[PUGL_SAMPLES] = 1;
  }
  if (view->hints[PUGL_DOUBLE_BUFFER] == PUGL_DONT_CARE) {
    view->hints[PUGL_DOUBLE_BUFFER] = 1;
  }
  if (view->hints[PUGL_SWAP_INTERVAL] == PUGL_DONT_CARE) {
    view->hints[PUGL_SWAP_INTERVAL] = 1;
  }

  // clang-format off
  const int pixelAttrs[] = {
    WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
    WGL_ACCELERATION_ARB,   WGL_FULL_ACCELERATION_ARB,
    WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
    WGL_DOUBLE_BUFFER_ARB,  view->hints[PUGL_DOUBLE_BUFFER],
    WGL_PIXEL_TYPE_ARB,     WGL_TYPE_RGBA_ARB,
    WGL_SAMPLE_BUFFERS_ARB, view->hints[PUGL_SAMPLES] ? 1 : 0,
    WGL_SAMPLES_ARB,        view->hints[PUGL_SAMPLES],
    WGL_RED_BITS_ARB,       view->hints[PUGL_RED_BITS],
    WGL_GREEN_BITS_ARB,     view->hints[PUGL_GREEN_BITS],
    WGL_BLUE_BITS_ARB,      view->hints[PUGL_BLUE_BITS],
    WGL_ALPHA_BITS_ARB,     view->hints[PUGL_ALPHA_BITS],
    WGL_DEPTH_BITS_ARB,     view->hints[PUGL_DEPTH_BITS],
    WGL_STENCIL_BITS_ARB,   view->hints[PUGL_STENCIL_BITS],
    0,
  };
  // clang-format on

  PuglWinGlSurface* const surface =
    (PuglWinGlSurface*)calloc(1, sizeof(PuglWinGlSurface));
  impl->surface = surface;

  // Create fake window for getting at GL context
  PuglStatus         st      = PUGL_SUCCESS;
  PuglFakeWindow     fakeWin = {0, 0};
  static const char* title   = "Pugl Configuration";
  if ((st = puglWinCreateWindow(view, title, &fakeWin.hwnd, &fakeWin.hdc))) {
    return puglWinError(&fakeWin, st);
  }

  // Set pixel format for fake window
  const PuglWinPFD fakePfd  = puglWinGetPixelFormatDescriptor(view->hints);
  const int        fakePfId = ChoosePixelFormat(fakeWin.hdc, &fakePfd);
  if (!fakePfId || !SetPixelFormat(fakeWin.hdc, fakePfId, &fakePfd)) {
    return puglWinError(&fakeWin, PUGL_SET_FORMAT_FAILED);
  }

  // Create fake GL context to get at the functions we need
  HGLRC fakeRc = wglCreateContext(fakeWin.hdc);
  if (!fakeRc) {
    return puglWinError(&fakeWin, PUGL_CREATE_CONTEXT_FAILED);
  }

  // Enter fake context and get extension functions
  wglMakeCurrent(fakeWin.hdc, fakeRc);
  surface->procs = puglWinGlGetProcs();

  if (surface->procs.wglChoosePixelFormat) {
    // Choose pixel format based on attributes
    UINT numFormats = 0;
    if (!surface->procs.wglChoosePixelFormat(
          fakeWin.hdc, pixelAttrs, NULL, 1u, &impl->pfId, &numFormats)) {
      return puglWinError(&fakeWin, PUGL_SET_FORMAT_FAILED);
    }

    DescribePixelFormat(impl->hdc, impl->pfId, sizeof(impl->pfd), &impl->pfd);
  } else {
    // Modern extensions not available, use basic pixel format
    impl->pfd  = fakePfd;
    impl->pfId = fakePfId;
  }

  // Dispose of fake window and context
  wglMakeCurrent(NULL, NULL);
  wglDeleteContext(fakeRc);
  ReleaseDC(fakeWin.hwnd, fakeWin.hdc);
  DestroyWindow(fakeWin.hwnd);

  return PUGL_SUCCESS;
}

static PuglStatus
puglWinGlCreate(PuglView* view)
{
  PuglInternals* const    impl    = view->impl;
  PuglWinGlSurface* const surface = (PuglWinGlSurface*)impl->surface;
  PuglStatus              st      = PUGL_SUCCESS;

  const int contextAttribs[] = {
    WGL_CONTEXT_MAJOR_VERSION_ARB,
    view->hints[PUGL_CONTEXT_VERSION_MAJOR],

    WGL_CONTEXT_MINOR_VERSION_ARB,
    view->hints[PUGL_CONTEXT_VERSION_MINOR],

    WGL_CONTEXT_FLAGS_ARB,
    (view->hints[PUGL_USE_DEBUG_CONTEXT] ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),

    WGL_CONTEXT_PROFILE_MASK_ARB,
    (view->hints[PUGL_USE_COMPAT_PROFILE]
       ? WGL_CONTEXT_CORE_PROFILE_BIT_ARB
       : WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB),

    0};

  // Create real window with desired pixel format
  if ((st = puglWinCreateWindow(view, "Pugl", &impl->hwnd, &impl->hdc))) {
    return st;
  } else if (!SetPixelFormat(impl->hdc, impl->pfId, &impl->pfd)) {
    ReleaseDC(impl->hwnd, impl->hdc);
    DestroyWindow(impl->hwnd);
    impl->hwnd = NULL;
    impl->hdc  = NULL;
    return PUGL_SET_FORMAT_FAILED;
  }

  // Create GL context
  if (surface->procs.wglCreateContextAttribs &&
      !(surface->hglrc = surface->procs.wglCreateContextAttribs(
          impl->hdc, 0, contextAttribs))) {
    return PUGL_CREATE_CONTEXT_FAILED;
  } else if (!(surface->hglrc = wglCreateContext(impl->hdc))) {
    return PUGL_CREATE_CONTEXT_FAILED;
  }

  // Enter context and set swap interval
  wglMakeCurrent(impl->hdc, surface->hglrc);
  const int swapInterval = view->hints[PUGL_SWAP_INTERVAL];
  if (surface->procs.wglSwapInterval && swapInterval != PUGL_DONT_CARE) {
    surface->procs.wglSwapInterval(swapInterval);
  }

  return PUGL_SUCCESS;
}

static PuglStatus
puglWinGlDestroy(PuglView* view)
{
  PuglWinGlSurface* surface = (PuglWinGlSurface*)view->impl->surface;
  if (surface) {
    wglMakeCurrent(NULL, NULL);
    wglDeleteContext(surface->hglrc);
    free(surface);
    view->impl->surface = NULL;
  }

  return PUGL_SUCCESS;
}

static PuglStatus
puglWinGlEnter(PuglView* view, const PuglExposeEvent* expose)
{
  PuglWinGlSurface* surface = (PuglWinGlSurface*)view->impl->surface;

  wglMakeCurrent(view->impl->hdc, surface->hglrc);

  if (expose) {
    PAINTSTRUCT ps;
    BeginPaint(view->impl->hwnd, &ps);
  }

  return PUGL_SUCCESS;
}

static PuglStatus
puglWinGlLeave(PuglView* view, const PuglExposeEvent* expose)
{
  if (expose) {
    PAINTSTRUCT ps;
    EndPaint(view->impl->hwnd, &ps);
    SwapBuffers(view->impl->hdc);
  }

  wglMakeCurrent(NULL, NULL);
  return PUGL_SUCCESS;
}

PuglGlFunc
puglGetProcAddress(const char* name)
{
  const PuglGlFunc func = (PuglGlFunc)wglGetProcAddress(name);

  /* Windows has the annoying property that wglGetProcAddress returns NULL
     for functions from OpenGL 1.1, so we fall back to pulling them directly
     from opengl32.dll */

  return func
           ? func
           : (PuglGlFunc)GetProcAddress(GetModuleHandle("opengl32.dll"), name);
}

PuglStatus
puglEnterContext(PuglView* view)
{
  return view->backend->enter(view, NULL);
}

PuglStatus
puglLeaveContext(PuglView* view)
{
  return view->backend->leave(view, NULL);
}

const PuglBackend*
puglGlBackend(void)
{
  static const PuglBackend backend = {puglWinGlConfigure,
                                      puglWinGlCreate,
                                      puglWinGlDestroy,
                                      puglWinGlEnter,
                                      puglWinGlLeave,
                                      puglStubGetContext};

  return &backend;
}
