/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"

#if SDL_VIDEO_DRIVER_X11

#include "SDL_x11video.h"
#include "SDL_assert.h"

/* GLX implementation of SDL OpenGL support */

#if SDL_VIDEO_OPENGL_GLX
#include "SDL_loadso.h"

#if defined(__IRIX__)
/* IRIX doesn't have a GL library versioning system */
#define DEFAULT_OPENGL	"libGL.so"
#elif defined(__MACOSX__)
#define DEFAULT_OPENGL	"/usr/X11R6/lib/libGL.1.dylib"
#elif defined(__QNXNTO__)
#define DEFAULT_OPENGL	"libGL.so.3"
#else
#define DEFAULT_OPENGL	"libGL.so.1"
#endif

#ifndef GLX_NONE_EXT
#define GLX_NONE_EXT                       0x8000
#endif

#ifndef GLX_ARB_multisample
#define GLX_ARB_multisample
#define GLX_SAMPLE_BUFFERS_ARB             100000
#define GLX_SAMPLES_ARB                    100001
#endif

#ifndef GLX_EXT_visual_rating
#define GLX_EXT_visual_rating
#define GLX_VISUAL_CAVEAT_EXT              0x20
#define GLX_NONE_EXT                       0x8000
#define GLX_SLOW_VISUAL_EXT                0x8001
#define GLX_NON_CONFORMANT_VISUAL_EXT      0x800D
#endif

#ifndef GLX_ARB_create_context
#define GLX_ARB_create_context
#define GLX_CONTEXT_MAJOR_VERSION_ARB      0x2091
#define GLX_CONTEXT_MINOR_VERSION_ARB      0x2092
#define GLX_CONTEXT_FLAGS_ARB              0x2094
#define GLX_CONTEXT_DEBUG_BIT_ARB          0x0001
#define GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB 0x0002

#ifndef GLX_EXT_swap_control
#define GLX_SWAP_INTERVAL_EXT              0x20F1
#define GLX_MAX_SWAP_INTERVAL_EXT          0x20F2
#endif

/* Typedef for the GL 3.0 context creation function */
typedef GLXContext(*PFNGLXCREATECONTEXTATTRIBSARBPROC) (Display * dpy,
                                                        GLXFBConfig config,
                                                        GLXContext
                                                        share_context,
                                                        Bool direct,
                                                        const int
                                                        *attrib_list);
#endif

#define OPENGL_REQUIRES_DLOPEN
#if defined(OPENGL_REQUIRES_DLOPEN) && defined(SDL_LOADSO_DLOPEN)
#include <dlfcn.h>
#define GL_LoadObject(X)	dlopen(X, (RTLD_NOW|RTLD_GLOBAL))
#define GL_LoadFunction		dlsym
#define GL_UnloadObject		dlclose
#else
#define GL_LoadObject	SDL_LoadObject
#define GL_LoadFunction	SDL_LoadFunction
#define GL_UnloadObject	SDL_UnloadObject
#endif

static void X11_GL_InitExtensions(_THIS);


int
X11_GL_LoadLibrary(_THIS, const char *path)
{
    void *handle;

    /* Load the OpenGL library */
    if (path == NULL) {
        path = SDL_getenv("SDL_OPENGL_LIBRARY");
    }
    if (path == NULL) {
        path = DEFAULT_OPENGL;
    }
    _this->gl_config.dll_handle = GL_LoadObject(path);
    if (!_this->gl_config.dll_handle) {
#if defined(OPENGL_REQUIRES_DLOPEN) && defined(SDL_LOADSO_DLOPEN)
        SDL_SetError("Failed loading %s: %s", path, dlerror());
#endif
        return -1;
    }
    SDL_strlcpy(_this->gl_config.driver_path, path,
                SDL_arraysize(_this->gl_config.driver_path));

    /* Allocate OpenGL memory */
    _this->gl_data =
        (struct SDL_GLDriverData *) SDL_calloc(1,
                                               sizeof(struct
                                                      SDL_GLDriverData));
    if (!_this->gl_data) {
        SDL_OutOfMemory();
        return -1;
    }

    /* Load function pointers */
    handle = _this->gl_config.dll_handle;
    _this->gl_data->glXGetProcAddress =
        (void *(*)(const GLubyte *))
            GL_LoadFunction(handle, "glXGetProcAddressARB");
    _this->gl_data->glXChooseVisual =
        (XVisualInfo * (*)(Display *, int, int *))
            X11_GL_GetProcAddress(_this, "glXChooseVisual");
    _this->gl_data->glXCreateContext =
        (GLXContext(*)(Display *, XVisualInfo *, GLXContext, int))
            X11_GL_GetProcAddress(_this, "glXCreateContext");
    _this->gl_data->glXDestroyContext =
        (void (*)(Display *, GLXContext))
            X11_GL_GetProcAddress(_this, "glXDestroyContext");
    _this->gl_data->glXMakeCurrent =
        (int (*)(Display *, GLXDrawable, GLXContext))
            X11_GL_GetProcAddress(_this, "glXMakeCurrent");
    _this->gl_data->glXSwapBuffers =
        (void (*)(Display *, GLXDrawable))
            X11_GL_GetProcAddress(_this, "glXSwapBuffers");
    _this->gl_data->glXQueryDrawable =
        (void (*)(Display*,GLXDrawable,int,unsigned int*))
            X11_GL_GetProcAddress(_this, "glXQueryDrawable");

    if (!_this->gl_data->glXChooseVisual ||
        !_this->gl_data->glXCreateContext ||
        !_this->gl_data->glXDestroyContext ||
        !_this->gl_data->glXMakeCurrent ||
        !_this->gl_data->glXSwapBuffers) {
        SDL_SetError("Could not retrieve OpenGL functions");
        return -1;
    }

    /* Initialize extensions */
    X11_GL_InitExtensions(_this);

    return 0;
}

void *
X11_GL_GetProcAddress(_THIS, const char *proc)
{
    if (_this->gl_data->glXGetProcAddress) {
        return _this->gl_data->glXGetProcAddress((const GLubyte *) proc);
    }
    return GL_LoadFunction(_this->gl_config.dll_handle, proc);
}

void
X11_GL_UnloadLibrary(_THIS)
{
    /* Don't actually unload the library, since it may have registered
     * X11 shutdown hooks, per the notes at:
     * http://dri.sourceforge.net/doc/DRIuserguide.html
     */
#if 0
    GL_UnloadObject(_this->gl_config.dll_handle);
    _this->gl_config.dll_handle = NULL;
#endif

    /* Free OpenGL memory */
    if (_this->gl_data) {
        SDL_free(_this->gl_data);
        _this->gl_data = NULL;
    }
}

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
X11_GL_InitExtensions(_THIS)
{
    Display *display = ((SDL_VideoData *) _this->driverdata)->display;
    int screen = DefaultScreen(display);
    XVisualInfo *vinfo;
    XSetWindowAttributes xattr;
    Window w;
    GLXContext context;
    const char *(*glXQueryExtensionsStringFunc) (Display *, int);
    const char *extensions;

    vinfo = X11_GL_GetVisual(_this, display, screen);
    if (!vinfo) {
        return;
    }
    xattr.background_pixel = 0;
    xattr.border_pixel = 0;
    xattr.colormap =
        XCreateColormap(display, RootWindow(display, screen), vinfo->visual,
                        AllocNone);
    w = XCreateWindow(display, RootWindow(display, screen), 0, 0, 32, 32, 0,
                      vinfo->depth, InputOutput, vinfo->visual,
                      (CWBackPixel | CWBorderPixel | CWColormap), &xattr);
    context = _this->gl_data->glXCreateContext(display, vinfo, NULL, True);
    if (context) {
        _this->gl_data->glXMakeCurrent(display, w, context);
    }
    XFree(vinfo);

    glXQueryExtensionsStringFunc =
        (const char *(*)(Display *, int)) X11_GL_GetProcAddress(_this,
                                                                "glXQueryExtensionsString");
    if (glXQueryExtensionsStringFunc) {
        extensions = glXQueryExtensionsStringFunc(display, screen);
    } else {
        extensions = NULL;
    }

    /* Check for GLX_EXT_swap_control */
    if (HasExtension("GLX_EXT_swap_control", extensions)) {
        _this->gl_data->glXSwapIntervalEXT =
            (int (*)(Display*,GLXDrawable,int))
                X11_GL_GetProcAddress(_this, "glXSwapIntervalEXT");
    }

    /* Check for GLX_MESA_swap_control */
    if (HasExtension("GLX_MESA_swap_control", extensions)) {
        _this->gl_data->glXSwapIntervalMESA =
            (int(*)(int)) X11_GL_GetProcAddress(_this, "glXSwapIntervalMESA");
        _this->gl_data->glXGetSwapIntervalMESA =
            (int(*)(void)) X11_GL_GetProcAddress(_this,
                                                   "glXGetSwapIntervalMESA");
    }

    /* Check for GLX_SGI_swap_control */
    if (HasExtension("GLX_SGI_swap_control", extensions)) {
        _this->gl_data->glXSwapIntervalSGI =
            (int (*)(int)) X11_GL_GetProcAddress(_this, "glXSwapIntervalSGI");
    }

    /* Check for GLX_EXT_visual_rating */
    if (HasExtension("GLX_EXT_visual_rating", extensions)) {
        _this->gl_data->HAS_GLX_EXT_visual_rating = SDL_TRUE;
    }

    if (context) {
        _this->gl_data->glXMakeCurrent(display, None, NULL);
        _this->gl_data->glXDestroyContext(display, context);
    }
    XDestroyWindow(display, w);
    X11_PumpEvents(_this);
}

int 
X11_GL_GetAttributes(_THIS, Display * display, int screen, int * attribs, int size)
{
    int i = 0;

    /* assert buffer is large enough to hold all SDL attributes. */ 
    /* assert(size >= 32);*/

    /* Setup our GLX attributes according to the gl_config. */
    attribs[i++] = GLX_RGBA;
    attribs[i++] = GLX_RED_SIZE;
    attribs[i++] = _this->gl_config.red_size;
    attribs[i++] = GLX_GREEN_SIZE;
    attribs[i++] = _this->gl_config.green_size;
    attribs[i++] = GLX_BLUE_SIZE;
    attribs[i++] = _this->gl_config.blue_size;

    if (_this->gl_config.alpha_size) {
        attribs[i++] = GLX_ALPHA_SIZE;
        attribs[i++] = _this->gl_config.alpha_size;
    }

    if (_this->gl_config.buffer_size) {
        attribs[i++] = GLX_BUFFER_SIZE;
        attribs[i++] = _this->gl_config.buffer_size;
    }

    if (_this->gl_config.double_buffer) {
        attribs[i++] = GLX_DOUBLEBUFFER;
    }

    attribs[i++] = GLX_DEPTH_SIZE;
    attribs[i++] = _this->gl_config.depth_size;

    if (_this->gl_config.stencil_size) {
        attribs[i++] = GLX_STENCIL_SIZE;
        attribs[i++] = _this->gl_config.stencil_size;
    }

    if (_this->gl_config.accum_red_size) {
        attribs[i++] = GLX_ACCUM_RED_SIZE;
        attribs[i++] = _this->gl_config.accum_red_size;
    }

    if (_this->gl_config.accum_green_size) {
        attribs[i++] = GLX_ACCUM_GREEN_SIZE;
        attribs[i++] = _this->gl_config.accum_green_size;
    }

    if (_this->gl_config.accum_blue_size) {
        attribs[i++] = GLX_ACCUM_BLUE_SIZE;
        attribs[i++] = _this->gl_config.accum_blue_size;
    }

    if (_this->gl_config.accum_alpha_size) {
        attribs[i++] = GLX_ACCUM_ALPHA_SIZE;
        attribs[i++] = _this->gl_config.accum_alpha_size;
    }

    if (_this->gl_config.stereo) {
        attribs[i++] = GLX_STEREO;
    }

    if (_this->gl_config.multisamplebuffers) {
        attribs[i++] = GLX_SAMPLE_BUFFERS_ARB;
        attribs[i++] = _this->gl_config.multisamplebuffers;
    }

    if (_this->gl_config.multisamplesamples) {
        attribs[i++] = GLX_SAMPLES_ARB;
        attribs[i++] = _this->gl_config.multisamplesamples;
    }

    if (_this->gl_config.accelerated >= 0 &&
        _this->gl_data->HAS_GLX_EXT_visual_rating) {
        attribs[i++] = GLX_VISUAL_CAVEAT_EXT;
        attribs[i++] = _this->gl_config.accelerated ? GLX_NONE_EXT :
                                                      GLX_SLOW_VISUAL_EXT;
    }

    attribs[i++] = None;
 
    return i;
}

XVisualInfo *
X11_GL_GetVisual(_THIS, Display * display, int screen)
{
    XVisualInfo *vinfo;

    /* 64 seems nice. */
    const int max_attrs = 64;
    int attribs[max_attrs];
    const int i = X11_GL_GetAttributes(_this,display,screen,attribs,max_attrs);
    SDL_assert(i <= max_attrs);

    if (!_this->gl_data) {
        /* The OpenGL library wasn't loaded, SDL_GetError() should have info */
        return NULL;
    }

    vinfo = _this->gl_data->glXChooseVisual(display, screen, attribs);
    if (!vinfo) {
        SDL_SetError("Couldn't find matching GLX visual");
    }
    return vinfo;
}

SDL_GLContext
X11_GL_CreateContext(_THIS, SDL_Window * window)
{
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
    Display *display = data->videodata->display;
    int screen =
        ((SDL_DisplayData *) SDL_GetDisplayForWindow(window)->driverdata)->screen;
    XWindowAttributes xattr;
    XVisualInfo v, *vinfo;
    int n;
    GLXContext context = NULL;

    /* We do this to create a clean separation between X and GLX errors. */
    XSync(display, False);
    XGetWindowAttributes(display, data->xwindow, &xattr);
    v.screen = screen;
    v.visualid = XVisualIDFromVisual(xattr.visual);
    vinfo = XGetVisualInfo(display, VisualScreenMask | VisualIDMask, &v, &n);
    if (vinfo) {
        if (_this->gl_config.major_version < 3) {
            context =
                _this->gl_data->glXCreateContext(display, vinfo, NULL, True);
        } else {
            /* If we want a GL 3.0 context or later we need to get a temporary
               context to grab the new context creation function */
            GLXContext temp_context =
                _this->gl_data->glXCreateContext(display, vinfo, NULL, True);
            if (!temp_context) {
                SDL_SetError("Could not create GL context");
                return NULL;
            } else {
                int attribs[] = {
                    GLX_CONTEXT_MAJOR_VERSION_ARB,
                    _this->gl_config.major_version,
                    GLX_CONTEXT_MINOR_VERSION_ARB,
                    _this->gl_config.minor_version,
                    0
                };

                /* Get a pointer to the context creation function for GL 3.0 */
                PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribs =
                    (PFNGLXCREATECONTEXTATTRIBSARBPROC) _this->gl_data->
                    glXGetProcAddress((GLubyte *)
                                      "glXCreateContextAttribsARB");
                if (!glXCreateContextAttribs) {
                    SDL_SetError("GL 3.x is not supported");
                    context = temp_context;
                } else {
                    int glxAttribs[64];

                    /* Create a GL 3.x context */
                    GLXFBConfig *framebuffer_config = NULL;
                    int fbcount = 0;
                    GLXFBConfig *(*glXChooseFBConfig) (Display * disp,
                                                       int screen,
                                                       const int *attrib_list,
                                                       int *nelements);

                    glXChooseFBConfig =
                        (GLXFBConfig *
                         (*)(Display *, int, const int *,
                             int *)) _this->gl_data->
                        glXGetProcAddress((GLubyte *) "glXChooseFBConfig");

                    X11_GL_GetAttributes(_this,display,screen,glxAttribs,64);

                    if (!glXChooseFBConfig
                        || !(framebuffer_config =
                             glXChooseFBConfig(display,
                                               DefaultScreen(display), glxAttribs,
                                               &fbcount))) {
                        SDL_SetError
                            ("No good framebuffers found. GL 3.x disabled");
                        context = temp_context;
                    } else {
                        context =
                            glXCreateContextAttribs(display,
                                                    framebuffer_config[0],
                                                    NULL, True, attribs);
                        _this->gl_data->glXDestroyContext(display,
                                                          temp_context);
                    }
                }
            }
        }
        XFree(vinfo);
    }
    XSync(display, False);

    if (!context) {
        SDL_SetError("Could not create GL context");
        return NULL;
    }

    if (X11_GL_MakeCurrent(_this, window, context) < 0) {
        X11_GL_DeleteContext(_this, context);
        return NULL;
    }

    return context;
}

int
X11_GL_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context)
{
    Display *display = ((SDL_VideoData *) _this->driverdata)->display;
    Window drawable =
        (window ? ((SDL_WindowData *) window->driverdata)->xwindow : None);
    GLXContext glx_context = (GLXContext) context;
    int status;

    status = 0;
    if (!_this->gl_data->glXMakeCurrent(display, drawable, glx_context)) {
        SDL_SetError("Unable to make GL context current");
        status = -1;
    }
    XSync(display, False);

    return (status);
}

/* 
   0 is a valid argument to glxSwapInterval(MESA|EXT) and setting it to 0
   will undo the effect of a previous call with a value that is greater
   than zero (or at least that is what the docs say). OTOH, 0 is an invalid
   argument to glxSwapIntervalSGI and it returns an error if you call it
   with 0 as an argument.
*/

static int swapinterval = -1;
int
X11_GL_SetSwapInterval(_THIS, int interval)
{
    int status;

    if (_this->gl_data->glXSwapIntervalEXT) {
        Display *display = ((SDL_VideoData *) _this->driverdata)->display;
        const SDL_WindowData *windowdata = (SDL_WindowData *)
            _this->current_glwin->driverdata;
        Window drawable = windowdata->xwindow;
        status = _this->gl_data->glXSwapIntervalEXT(display,drawable,interval);
        if (status != 0) {
            SDL_SetError("glxSwapIntervalEXT failed");
            status = -1;
        } else {
            swapinterval = interval;
        }
    } else if (_this->gl_data->glXSwapIntervalMESA) {
        status = _this->gl_data->glXSwapIntervalMESA(interval);
        if (status != 0) {
            SDL_SetError("glxSwapIntervalMESA failed");
            status = -1;
        } else {
            swapinterval = interval;
        }
    } else if (_this->gl_data->glXSwapIntervalSGI) {
        status = _this->gl_data->glXSwapIntervalSGI(interval);
        if (status != 0) {
            SDL_SetError("glxSwapIntervalSGI failed");
            status = -1;
        } else {
            swapinterval = interval;
        }
    } else {
        SDL_Unsupported();
        status = -1;
    }
    return status;
}

int
X11_GL_GetSwapInterval(_THIS)
{
    if (_this->gl_data->glXSwapIntervalEXT) {
        Display *display = ((SDL_VideoData *) _this->driverdata)->display;
        const SDL_WindowData *windowdata = (SDL_WindowData *)
            _this->current_glwin->driverdata;
        Window drawable = windowdata->xwindow;
        unsigned int value = 0;
        _this->gl_data->glXQueryDrawable(display, drawable,
                                         GLX_SWAP_INTERVAL_EXT, &value);
        return (int) value;
    } else if (_this->gl_data->glXGetSwapIntervalMESA) {
        return _this->gl_data->glXGetSwapIntervalMESA();
    } else {
        return swapinterval;
    }
}

void
X11_GL_SwapWindow(_THIS, SDL_Window * window)
{
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
    Display *display = data->videodata->display;

    _this->gl_data->glXSwapBuffers(display, data->xwindow);
}

void
X11_GL_DeleteContext(_THIS, SDL_GLContext context)
{
    Display *display = ((SDL_VideoData *) _this->driverdata)->display;
    GLXContext glx_context = (GLXContext) context;

    _this->gl_data->glXDestroyContext(display, glx_context);
    XSync(display, False);
}

#endif /* SDL_VIDEO_OPENGL_GLX */

#endif /* SDL_VIDEO_DRIVER_X11 */

/* vi: set ts=4 sw=4 expandtab: */
