/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

#include "SDL_win32video.h"

/* WGL implementation of SDL OpenGL support */

#if SDL_VIDEO_OPENGL_WGL

#include "SDL_opengl.h"

#define DEFAULT_OPENGL "OPENGL32.DLL"

int

WIN_GL_LoadLibrary(_THIS, const char *path)

{

    LPTSTR wpath;

    HANDLE handle;

    if (_this->gl_config.driver_loaded) {

        if (path) {

            SDL_SetError("OpenGL library already loaded");

            return -1;

        } else {

            ++_this->gl_config.driver_loaded;

            return 0;

        }

    }

    if (path == NULL) {

        path = SDL_getenv("SDL_OPENGL_LIBRARY");

    }

    if (path == NULL) {

        path = DEFAULT_OPENGL;

    }

    wpath = WIN_UTF8ToString(path);

    handle = LoadLibrary(wpath);

    SDL_free(wpath);

    if (!handle) {

        char message[1024];

        SDL_snprintf(message, SDL_arraysize(message), "LoadLibrary(\"%s\")",

                     path);

        WIN_SetError(message);

        return -1;

    }

    /* Load function pointers */

    _this->gl_data->wglGetProcAddress = (void *(WINAPI *) (const char *))

        GetProcAddress(handle, "wglGetProcAddress");

    _this->gl_data->wglCreateContext = (HGLRC(WINAPI *) (HDC))

        GetProcAddress(handle, "wglCreateContext");

    _this->gl_data->wglDeleteContext = (BOOL(WINAPI *) (HGLRC))

        GetProcAddress(handle, "wglDeleteContext");

    _this->gl_data->wglMakeCurrent = (BOOL(WINAPI *) (HDC, HGLRC))

        GetProcAddress(handle, "wglMakeCurrent");

    _this->gl_data->wglSwapIntervalEXT = (void (WINAPI *) (int))

        GetProcAddress(handle, "wglSwapIntervalEXT");

    _this->gl_data->wglGetSwapIntervalEXT = (int (WINAPI *) (void))

        GetProcAddress(handle, "wglGetSwapIntervalEXT");

    if (!_this->gl_data->wglGetProcAddress ||

        !_this->gl_data->wglCreateContext ||

        !_this->gl_data->wglDeleteContext ||

        !_this->gl_data->wglMakeCurrent) {

        SDL_SetError("Could not retrieve OpenGL functions");

        FreeLibrary(handle);

        return -1;

    }

    _this->gl_config.dll_handle = handle;

    SDL_strlcpy(_this->gl_config.driver_path, path,

                SDL_arraysize(_this->gl_config.driver_path));

    _this->gl_config.driver_loaded = 1;

    return 0;

}

void *

WIN_GL_GetProcAddress(_THIS, const char *proc)

{

    void *func;

    /* This is to pick up extensions */

    func = _this->gl_data->wglGetProcAddress(proc);

    if (!func) {

        /* This is probably a normal GL function */

        func = GetProcAddress(_this->gl_config.dll_handle, proc);

    }

    return func;

}

static void

WIN_GL_UnloadLibrary(_THIS)

{

    if (_this->gl_config.driver_loaded > 0) {

        if (--_this->gl_config.driver_loaded > 0) {

            return;

        }

        FreeLibrary((HMODULE) _this->gl_config.dll_handle);

        _this->gl_config.dll_handle = NULL;

    }

}

static void

WIN_GL_SetupPixelFormat(_THIS, PIXELFORMATDESCRIPTOR * pfd)

{

    SDL_zerop(pfd);

    pfd->nSize = sizeof(*pfd);

    pfd->nVersion = 1;

    pfd->dwFlags = (PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL);

    if (_this->gl_config.double_buffer) {

        pfd->dwFlags |= PFD_DOUBLEBUFFER;

    }

    if (_this->gl_config.stereo) {

        pfd->dwFlags |= PFD_STEREO;

    }

    pfd->iLayerType = PFD_MAIN_PLANE;

    pfd->iPixelType = PFD_TYPE_RGBA;

    pfd->cRedBits = _this->gl_config.red_size;

    pfd->cGreenBits = _this->gl_config.green_size;

    pfd->cBlueBits = _this->gl_config.blue_size;

    pfd->cAlphaBits = _this->gl_config.alpha_size;

    if (_this->gl_config.buffer_size) {

        pfd->cColorBits =

            _this->gl_config.buffer_size - _this->gl_config.alpha_size;

    } else {

        pfd->cColorBits = (pfd->cRedBits + pfd->cGreenBits + pfd->cBlueBits);

    }

    pfd->cAccumRedBits = _this->gl_config.accum_red_size;

    pfd->cAccumGreenBits = _this->gl_config.accum_green_size;

    pfd->cAccumBlueBits = _this->gl_config.accum_blue_size;

    pfd->cAccumAlphaBits = _this->gl_config.accum_alpha_size;

    pfd->cAccumBits =

        (pfd->cAccumRedBits + pfd->cAccumGreenBits + pfd->cAccumBlueBits +

         pfd->cAccumAlphaBits);

    pfd->cDepthBits = _this->gl_config.depth_size;

    pfd->cStencilBits = _this->gl_config.stencil_size;

}

/* Choose the closest pixel format that meets or exceeds the target.

   FIXME: Should we weight any particular attribute over any other?

*/

static int

WIN_GL_ChoosePixelFormat(HDC hdc, PIXELFORMATDESCRIPTOR * target)

{

    PIXELFORMATDESCRIPTOR pfd;

    int count, index, best = 0;

    unsigned int dist, best_dist = ~0U;

    count = DescribePixelFormat(hdc, 1, sizeof(pfd), NULL);

    for (index = 1; index <= count; index++) {

        if (!DescribePixelFormat(hdc, index, sizeof(pfd), &pfd)) {

            continue;

        }

        if ((pfd.dwFlags & target->dwFlags) != target->dwFlags) {

            continue;

        }

        if (pfd.iLayerType != target->iLayerType) {

            continue;

        }

        if (pfd.iPixelType != target->iPixelType) {

            continue;

        }

        dist = 0;

        if (pfd.cColorBits < target->cColorBits) {

            continue;

        } else {

            dist += (pfd.cColorBits - target->cColorBits);

        }

        if (pfd.cRedBits < target->cRedBits) {

            continue;

        } else {

            dist += (pfd.cRedBits - target->cRedBits);

        }

        if (pfd.cGreenBits < target->cGreenBits) {

            continue;

        } else {

            dist += (pfd.cGreenBits - target->cGreenBits);

        }

        if (pfd.cBlueBits < target->cBlueBits) {

            continue;

        } else {

            dist += (pfd.cBlueBits - target->cBlueBits);

        }

        if (pfd.cAlphaBits < target->cAlphaBits) {

            continue;

        } else {

            dist += (pfd.cAlphaBits - target->cAlphaBits);

        }

        if (pfd.cAccumBits < target->cAccumBits) {

            continue;

        } else {

            dist += (pfd.cAccumBits - target->cAccumBits);

        }

        if (pfd.cAccumRedBits < target->cAccumRedBits) {

            continue;

        } else {

            dist += (pfd.cAccumRedBits - target->cAccumRedBits);

        }

        if (pfd.cAccumGreenBits < target->cAccumGreenBits) {

            continue;

        } else {

            dist += (pfd.cAccumGreenBits - target->cAccumGreenBits);

        }

        if (pfd.cAccumBlueBits < target->cAccumBlueBits) {

            continue;

        } else {

            dist += (pfd.cAccumBlueBits - target->cAccumBlueBits);

        }

        if (pfd.cAccumAlphaBits < target->cAccumAlphaBits) {

            continue;

        } else {

            dist += (pfd.cAccumAlphaBits - target->cAccumAlphaBits);

        }

        if (pfd.cDepthBits < target->cDepthBits) {

            continue;

        } else {

            dist += (pfd.cDepthBits - target->cDepthBits);

        }

        if (pfd.cStencilBits < target->cStencilBits) {

            continue;

        } else {

            dist += (pfd.cStencilBits - target->cStencilBits);

        }

        if (dist < best_dist) {

            best = index;

            best_dist = dist;

        }

    }

    return best;

}

static SDL_bool

HasExtension(const char *extension, const char *extensions)

{

    const char *start;

    const char *where, *terminator;

    /* Extension names should not have spaces. */

    where = SDL_strchr(extension, ' ');

    if (where || *extension == '\0')

        return SDL_FALSE;

    if (!extensions)

        return SDL_FALSE;

    /* It takes a bit of care to be fool-proof about parsing the

     * OpenGL extensions string. Don't be fooled by sub-strings,

     * etc. */

    start = extensions;

    for (;;) {

        where = SDL_strstr(start, extension);

        if (!where)

            break;

        terminator = where + SDL_strlen(extension);

        if (where == start || *(where - 1) == ' ')

            if (*terminator == ' ' || *terminator == '\0')

                return SDL_TRUE;

        start = terminator;

    }

    return SDL_FALSE;

}

static void

{

    const char *(WINAPI * wglGetExtensionsStringARB) (HDC) = 0;

    const char *extensions;

    wglGetExtensionsStringARB = (const char *(WINAPI *) (HDC))

        _this->gl_data->wglGetProcAddress("wglGetExtensionsStringARB");

    if (wglGetExtensionsStringARB) {

        extensions = wglGetExtensionsStringARB(hdc);

    } else {

        extensions = NULL;

    }

    /* Check for WGL_ARB_pixel_format */

    _this->gl_data->WGL_ARB_pixel_format = 0;

    if (HasExtension("WGL_ARB_pixel_format", extensions)) {

        _this->gl_data->wglChoosePixelFormatARB = (BOOL(WINAPI *)

                                                   (HDC, const int *,

                                                    const FLOAT *, UINT,

                                                    int *, UINT *))

            WIN_GL_GetProcAddress(_this, "wglChoosePixelFormatARB");

        _this->gl_data->wglGetPixelFormatAttribivARB =

            (BOOL(WINAPI *) (HDC, int, int, UINT, const int *, int *))

            WIN_GL_GetProcAddress(_this, "wglGetPixelFormatAttribivARB");

        if ((_this->gl_data->wglChoosePixelFormatARB != NULL) &&

            (_this->gl_data->wglGetPixelFormatAttribivARB != NULL)) {

            _this->gl_data->WGL_ARB_pixel_format = 1;

        }

    }

    /* Check for WGL_EXT_swap_control */

    if (HasExtension("WGL_EXT_swap_control", extensions)) {

        _this->gl_data->wglSwapIntervalEXT =

            WIN_GL_GetProcAddress(_this, "wglSwapIntervalEXT");

        _this->gl_data->wglGetSwapIntervalEXT =

            WIN_GL_GetProcAddress(_this, "wglGetSwapIntervalEXT");

    }

    if (hglrc) {

        _this->gl_data->wglMakeCurrent(NULL, NULL);

        _this->gl_data->wglDeleteContext(hglrc);

    }

    ReleaseDC(hwnd, hdc);

    DestroyWindow(hwnd);

    WIN_PumpEvents(_this);

}

static int

WIN_GL_Initialize(_THIS)

{

    if (_this->gl_data) {

        ++_this->gl_data->initialized;

        return 0;

    }

    _this->gl_data =

        (struct SDL_GLDriverData *) SDL_calloc(1,

                                               sizeof(struct

                                                      SDL_GLDriverData));

    if (!_this->gl_data) {

        SDL_OutOfMemory();

        return -1;

    }

    _this->gl_data->initialized = 1;

    if (WIN_GL_LoadLibrary(_this, NULL) < 0) {

        return -1;

    }

    return 0;

}

static void

WIN_GL_Shutdown(_THIS)

{

    if (!_this->gl_data || (--_this->gl_data->initialized > 0)) {

        return;

    }

    WIN_GL_UnloadLibrary(_this);

    SDL_free(_this->gl_data);

    _this->gl_data = NULL;

}

int

WIN_GL_SetupWindow(_THIS, SDL_Window * window)

{

    HDC hdc = ((SDL_WindowData *) window->driverdata)->hdc;

    PIXELFORMATDESCRIPTOR pfd;

    int pixel_format;

    int iAttribs[64];

    int *iAttr;

    float fAttribs[1] = { 0 };

    if (WIN_GL_Initialize(_this) < 0) {

        return -1;

    }

    WIN_GL_SetupPixelFormat(_this, &pfd);

    /* setup WGL_ARB_pixel_format attribs */

    iAttr = &iAttribs[0];

    *iAttr++ = WGL_DRAW_TO_WINDOW_ARB;

    *iAttr++ = GL_TRUE;

    *iAttr++ = WGL_ACCELERATION_ARB;

    *iAttr++ = WGL_FULL_ACCELERATION_ARB;

    *iAttr++ = WGL_RED_BITS_ARB;

    *iAttr++ = _this->gl_config.red_size;

    *iAttr++ = WGL_GREEN_BITS_ARB;

    *iAttr++ = _this->gl_config.green_size;

    *iAttr++ = WGL_BLUE_BITS_ARB;

    *iAttr++ = _this->gl_config.blue_size;

    if (_this->gl_config.alpha_size) {

        *iAttr++ = WGL_ALPHA_BITS_ARB;

        *iAttr++ = _this->gl_config.alpha_size;

    }

    *iAttr++ = WGL_DOUBLE_BUFFER_ARB;

    *iAttr++ = _this->gl_config.double_buffer;

    *iAttr++ = WGL_DEPTH_BITS_ARB;

    *iAttr++ = _this->gl_config.depth_size;

    if (_this->gl_config.stencil_size) {

        *iAttr++ = WGL_STENCIL_BITS_ARB;

        *iAttr++ = _this->gl_config.stencil_size;

    }

    if (_this->gl_config.accum_red_size) {

        *iAttr++ = WGL_ACCUM_RED_BITS_ARB;

        *iAttr++ = _this->gl_config.accum_red_size;

    }

    if (_this->gl_config.accum_green_size) {

        *iAttr++ = WGL_ACCUM_GREEN_BITS_ARB;

        *iAttr++ = _this->gl_config.accum_green_size;

    }

    if (_this->gl_config.accum_blue_size) {

        *iAttr++ = WGL_ACCUM_BLUE_BITS_ARB;

        *iAttr++ = _this->gl_config.accum_blue_size;

    }

    if (_this->gl_config.accum_alpha_size) {

        *iAttr++ = WGL_ACCUM_ALPHA_BITS_ARB;

        *iAttr++ = _this->gl_config.accum_alpha_size;

    }

    if (_this->gl_config.stereo) {

        *iAttr++ = WGL_STEREO_ARB;

        *iAttr++ = GL_TRUE;

    }

    if (_this->gl_config.multisamplebuffers) {

        *iAttr++ = WGL_SAMPLE_BUFFERS_ARB;

        *iAttr++ = _this->gl_config.multisamplebuffers;

    }

    if (_this->gl_config.multisamplesamples) {

        *iAttr++ = WGL_SAMPLES_ARB;

        *iAttr++ = _this->gl_config.multisamplesamples;

    }

    if (_this->gl_config.accelerated >= 0) {

        *iAttr++ = WGL_ACCELERATION_ARB;

        *iAttr++ =

            (_this->gl_config.

             accelerated ? WGL_GENERIC_ACCELERATION_ARB :

             WGL_NO_ACCELERATION_ARB);

    }

    *iAttr = 0;

    /* Choose and set the closest available pixel format */

        pixel_format = WIN_GL_ChoosePixelFormat(hdc, &pfd);

    }

    if (!pixel_format) {

        SDL_SetError("No matching GL pixel format available");

        return -1;

    }

    if (!SetPixelFormat(hdc, pixel_format, &pfd)) {

        WIN_SetError("SetPixelFormat()");

        return (-1);