/*
 * Copyright © 2017 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

/*
 * Tests GLX config/visual selection and sRGB. See init_glx() function for
 * different methods for selection.
 *
 * g++ -g -ggdb -o glxapp test.cpp -lX11 -lXrender -lGL
 *
 */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>
#include <X11/extensions/Xrender.h>

#include <GL/glx.h>
#include <GL/glxext.h>

#include <GL/gl.h>
#include <GL/glext.h>

static Visual*
find_depth_visual(Display *dpy, int scr, int depth)
{
  XVisualInfo *xvi;
  XVisualInfo vtemplate;
  int nvi, i;
  XRenderPictFormat *format;
  Visual *visual;

  vtemplate.screen = scr;
  vtemplate.depth = depth;
  vtemplate.c_class = TrueColor;
  xvi = XGetVisualInfo(dpy,
                       VisualScreenMask |
                       VisualDepthMask |
                       VisualClassMask,
                       &vtemplate,
                       &nvi);
  if (xvi == NULL)
    return NULL;

  visual = NULL;
  for (i = 0; i < nvi; i++) {
    format = XRenderFindVisualFormat (dpy, xvi[i].visual);
    if (format->type == PictTypeDirect && format->direct.alphaMask) {
      visual = xvi[i].visual;
      break;
    }
  }
  XFree (xvi);
  return visual;
}

static Bool WaitForNotify(Display *d, XEvent *e, char *arg)
{
  return (e->type == MapNotify) && (e->xmap.window == (Window) arg);
}

class glxapp
{
public:
   explicit glxapp(unsigned w, unsigned h)
   {
      init_failed = true;

      xdpy  = XOpenDisplay(NULL);
      scr   = DefaultScreen(xdpy);
      root  = RootWindow(xdpy, scr);
      depth = DefaultDepth(xdpy, scr);
      xres  = ScreenOfDisplay(xdpy, scr)->width;
      yres  = ScreenOfDisplay(xdpy, scr)->height;

      glxctx = NULL;

#if 1
      // 'regular' visual
      vis = DefaultVisual(xdpy, scr);
#else
      // visual with per pixel alpha
      vis = find_depth_visual(xdpy, scr, 32);
      depth = 32;
#endif

      if (!vis) {
         fprintf(stderr, "could not find such X visual\n");
         return;
      }

      visual_id = XVisualIDFromVisual(vis);
      cmap = XCreateColormap(xdpy, root, vis, AllocNone);
      wa.background_pixel = 0x00000000;
      wa.colormap = cmap;
      wa.border_pixel = 0;

      XEvent event;

      // create and map X window
      xwin = XCreateWindow(xdpy,
                           root,
                           0,
                           0,
                           w,
                           h,
                           0,
                           depth,
                           InputOutput,
                           vis,
                           CWBackPixel | CWBorderPixel | CWColormap,
                           &wa);

      delete_atom = XInternAtom(xdpy, "WM_DELETE_WINDOW", False);
      XSetWMProtocols(xdpy, xwin, &delete_atom, 1);
      XSelectInput(xdpy, xwin, StructureNotifyMask | VisibilityNotify | ExposureMask | KeyPressMask);
      XClearWindow(xdpy, xwin);
      XMapWindow(xdpy, xwin);
      XFlush(xdpy);
      XIfEvent(xdpy, &event, WaitForNotify, (char*) xwin);

      fprintf(stderr, "created window with visual id %d\n", visual_id);
      init_failed = false;
   }

   int glx_attrib(GLXFBConfig config, int attr)
   {
      int value;
      glXGetFBConfigAttrib(xdpy, config, attr, &value);
      return value;
   }

   void print_conf(GLXFBConfig conf)
   {
      printf("using visual 0x%x (srgb %d) (rgba %d%d%d%d)\n",
             glx_attrib(conf, GLX_VISUAL_ID),
             glx_attrib(conf, GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB),
             glx_attrib(conf, GLX_RED_SIZE),
             glx_attrib(conf, GLX_GREEN_SIZE),
             glx_attrib(conf, GLX_BLUE_SIZE),
             glx_attrib(conf, GLX_ALPHA_SIZE));
   }

   /* 1. glXGetFBConfigs
    * 2. investigate attributes, match with x window visual id
    * 3. ask for sRGB via glXChooseVisual
    */
   bool init_glx_by_matching_visual()
   {
      int num_elements;
      GLXFBConfig *conf = glXGetFBConfigs(xdpy, scr, &num_elements);

      if (num_elements <= 0 || !conf)
         return false;

      // query window attributes, including visual id it got
      XWindowAttributes attributes;
      if (!XGetWindowAttributes(xdpy, xwin, &attributes))
      {
         fprintf(stderr, "error with XGetWindowAttributes\n");
         return false;
      }

      // paranoid check that visual id matches what we've got
      if (XVisualIDFromVisual(attributes.visual) != visual_id)
      {
         fprintf(stderr, "window has different visual than on creation\n");
         return false;
      }

      // find GLXFBConfig that matches our visual id and has srgb
      for (int i = 0; i < num_elements; i++) {

         if (glx_attrib(conf[i], GLX_VISUAL_ID) != visual_id)
            continue;

         fprintf(stderr, "found a matching visual id (%d)\n", visual_id);

         // ask for srgb
         int srgb_attr[] = {
            GLX_RENDER_TYPE, GLX_RGBA_BIT,
            GLX_RGBA,
            GLX_RED_SIZE,   8,
            GLX_GREEN_SIZE, 8,
            GLX_BLUE_SIZE,  8,
            GLX_ALPHA_SIZE, 0,
            GLX_DEPTH_SIZE, 8,
            GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB,
            None
         };

         XVisualInfo *vi = glXChooseVisual(xdpy, scr, srgb_attr);

         if (!vi) {
            printf("error with glXChooseVisual\n");
            return false;
         }

         print_conf(conf[i]);

         glxctx = glXCreateContext(xdpy, vi, NULL, True);
         glxwin = glXCreateWindow(xdpy, conf[i], xwin, NULL);
         XFree(vi);
      }
      return true;
   }

   /* 1. glXChooseFBConfig
    * 2. investigate attributes, match with GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT
    * 3. get visual with glXGetVisualFromFBConfig
    */
   bool init_glx_by_choosing_config()
   {
      const int attr[] = {
         GLX_RENDER_TYPE, GLX_RGBA_BIT,
         GLX_RED_SIZE, 4,
         GLX_GREEN_SIZE, 4,
         GLX_BLUE_SIZE, 4,
         GLX_ALPHA_SIZE, 0,
         GLX_DEPTH_SIZE, 8,
         GLX_DOUBLEBUFFER, True,
         GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT, True,
         None
      };

      int num_elements;
      GLXFBConfig *conf = glXChooseFBConfig(xdpy, scr, attr, &num_elements);

      if (num_elements <= 0 || !conf)
         return false;

      // search one that has GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT set
      for (int i = 0; i < num_elements; i++) {

         if (glx_attrib(conf[i], GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT) != 1)
            continue;

         XVisualInfo *vi = glXGetVisualFromFBConfig(xdpy, conf[i]);
         if (!vi) {
            printf("no srgb visual found!\n");
            return false;
         }

         print_conf(conf[i]);

         glxctx = glXCreateContext(xdpy, vi, NULL, True);
         glxwin = glXCreateWindow(xdpy, conf[i], xwin, NULL);
         return true;
      }
      return false;
   }

   /* 1. glXGetFBConfigs
    * 2. investigate attributes, match with GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT
    * 3. get visual with glXGetVisualFromFBConfig
    */
   bool init_glx_by_searching_for_srgb()
   {
      int num_elements;
      GLXFBConfig *conf = glXGetFBConfigs(xdpy, scr, &num_elements);

      if (num_elements <= 0 || !conf)
         return false;

      // search first config that has srgb support and has doublebuffer
      // and no alpha
      for (unsigned i = 0; i < num_elements; i++) {

         if (glx_attrib(conf[i], GLX_FRAMEBUFFER_SRGB_CAPABLE_EXT) != 1)
            continue;

         if (glx_attrib(conf[i], GLX_DOUBLEBUFFER) != 1)
            continue;

         if (glx_attrib(conf[i], GLX_ALPHA_SIZE) != 0)
            continue;

         XVisualInfo *vi = glXGetVisualFromFBConfig(xdpy, conf[i]);
         if (!vi) {
            printf("no srgb visual found for config!\n");
            return false;
         } else {

            print_conf(conf[i]);

            glxctx = glXCreateContext(xdpy, vi, NULL, True);
            glxwin = glXCreateWindow(xdpy, conf[i], xwin, NULL);
            XFree(vi);
            return true;
         }
      }
      return false;
   }

   bool init_glx()
   {
      if (init_failed)
         return false;

      // OPTION 1
      // this kind of works even though GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB is
      // set as 0 since glGetFramebufferAttachmentParameterivEXT returns 0x8c40
      //return init_glx_by_matching_visual();

      // OPTION 2
      // works nicely, has srgb set
      //return init_glx_by_searching_for_srgb();

      // OPTION 3
      // works nicely, has srgb set
      return init_glx_by_choosing_config();

      return false;
   }

   ~glxapp()
   {
      if (init_failed)
         return;

      if (glxctx) {
         glXMakeContextCurrent(xdpy, None, None, glxctx);
         glXDestroyContext(xdpy, glxctx);
      }

      XDestroyWindow(xdpy, xwin);
      XCloseDisplay(xdpy);
   }

   GLint ask_fb_param(GLenum p)
   {
      static PFNGLGETFRAMEBUFFERATTACHMENTPARAMETERIVEXTPROC func =
         (PFNGLGETFRAMEBUFFERATTACHMENTPARAMETERIVEXTPROC)
         glXGetProcAddressARB((const GLubyte*)
                              "glGetFramebufferAttachmentParameterivEXT");
      if (func) {
         GLint param = 0xdeadbeef;
         func(GL_DRAW_FRAMEBUFFER, GL_BACK_LEFT, p, &param);
         return param;
      }
      return 0xdeadbeef;
   }

   int exec()
   {
      if (init_failed)
         return -1;

      if (!glxctx)
         return -1;

      if (!glXMakeCurrent(xdpy, glxwin, glxctx)) {
         printf("glXMakeCurrent failed\n");
         return -1;
      }

      GLint fb_type = ask_fb_param(GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE);

      if (fb_type == GL_NONE) {
         printf("huh! maybe config was not doublebuffered?\n");
         return 0;
      }

      glClearColor(1, 1, 1, 1);

      XEvent event;
      long key_pressed;
      Bool done = False;

#define PRINT_PARAM(p) printf("%s 0x%x\n", #p, ask_fb_param(p));

      PRINT_PARAM(GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE);
      PRINT_PARAM(GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE);
      PRINT_PARAM(GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE);
      PRINT_PARAM(GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE);
      PRINT_PARAM(GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING);

      GLenum err = glGetError();
      if (err != GL_NO_ERROR) {
         printf("gl error 0x%x when asking fb parameters\n", err);
         return 0;
      }

      while (!done) {
         if (XEventsQueued(xdpy, QueuedAfterReading) <= 0) {
            glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
         } else {
            XNextEvent(xdpy, &event);
            switch (event.type) {
            case ButtonRelease:
               done = True;
               break;
            case KeyPress :
              key_pressed = XLookupKeysym((XKeyEvent *)&event, 0);
              if (key_pressed == XK_Escape)
                 done = True;
              break;
            case ClientMessage :
               if ((signed)event.xclient.data.l[0] == delete_atom)
                  done = True;
               break;
            }
         }
         glXSwapBuffers(xdpy, glxwin);
      }
      return 0;
   }

private:

  Display *xdpy;
  Window xwin;
  Window root;
  Atom delete_atom;

  XSetWindowAttributes wa;
  Colormap cmap;
  Visual *vis;

  GLXContext glxctx;
  GLXWindow glxwin;

  bool init_failed;

  // X window visual ID
  int visual_id;

  int scr;
  int depth;
  int xres;
  int yres;
};

int main()
{
   glxapp app(256, 256);

   if (!app.init_glx()) {
      printf("error initializing glx\n");
      return -1;
   }

   return app.exec();
}