#include "../include/mgl/mgl.h"
#include <X11/Xutil.h>
#include <X11/XKBlib.h>
#include <X11/extensions/Xrender.h>
#include <stdio.h>
#ifndef NDEBUG
#include <stdlib.h>
#endif

static mgl_context context;
static int init_count = 0;
static XErrorHandler prev_xerror = NULL;
static XIOErrorHandler prev_xioerror = NULL;

static int ignore_xerror(Display *display, XErrorEvent *ee) {
    (void)display;
    (void)ee;
    return 0;
}

static int ignore_xioerror(Display *display) {
    (void)display;
    return 0;
}

static int glx_context_init() {
    const int attr[] = {
        GLX_RENDER_TYPE, GLX_RGBA_BIT,
        GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
        GLX_DOUBLEBUFFER, True,
        GLX_RED_SIZE, 8,
        GLX_GREEN_SIZE, 8,
        GLX_BLUE_SIZE, 8,
        GLX_ALPHA_SIZE, 8,
        GLX_DEPTH_SIZE, 0,
        None
    };

    context.fbconfigs = NULL;
    context.visual_info = NULL;
    context.fbconfig = NULL;

    int numfbconfigs = 0;
    context.fbconfigs = context.gl.glXChooseFBConfig(context.connection, DefaultScreen(context.connection), attr, &numfbconfigs);
    for(int i = 0; i < numfbconfigs; i++) {
        context.visual_info = context.gl.glXGetVisualFromFBConfig(context.connection, context.fbconfigs[i]);
        if(!context.visual_info)
            continue;

        XRenderPictFormat *pict_format = XRenderFindVisualFormat(context.connection, ((XVisualInfo*)context.visual_info)->visual);
        if(!pict_format) {
            XFree(context.visual_info);
            context.visual_info = NULL;
            continue;
        }

        context.fbconfig = context.fbconfigs[i];
        if(pict_format->direct.alphaMask > 0)
            break;

        XFree(context.visual_info);
        context.visual_info = NULL;
        context.fbconfig = NULL;
    }

    if(!context.visual_info) {
        fprintf(stderr, "mgl error: no appropriate visual found\n");
        return -1;
    }

    return 0;
}

static void glx_context_deinit() {
    if(context.visual_info) {
        XFree(context.visual_info);
        context.visual_info = NULL;
    }

    if(context.fbconfigs) {
        XFree(context.fbconfigs);
        context.fbconfigs = NULL;
    }
}

int mgl_init(void) {
    ++init_count;
    if(init_count == 1) {
        context.connection = XOpenDisplay(NULL);
        if(!context.connection) {
            fprintf(stderr, "mgl error:XOpenDisplay(NULL) failed\n");
            mgl_deinit();
            return -1;
        }

        prev_xerror = XSetErrorHandler(ignore_xerror);
        prev_xioerror = XSetIOErrorHandler(ignore_xioerror);
        XInitThreads();
        XkbSetDetectableAutoRepeat(context.connection, True, NULL);

        context.wm_delete_window_atom = XInternAtom(context.connection, "WM_DELETE_WINDOW", False);
        if(!context.wm_delete_window_atom) {
            mgl_deinit();
            return -1;
        }

        context.net_wm_ping_atom = XInternAtom(context.connection, "_NET_WM_PING", True);
        context.net_wm_pid_atom = XInternAtom(context.connection, "_NET_WM_PID", True);

        if(mgl_gl_load(&context.gl) != 0) {
            mgl_deinit();
            return -1;
        }

        if(glx_context_init() != 0) {
            mgl_deinit();
            return -1;
        }
    }
    return 0;
}

void mgl_deinit(void) {
    if(init_count == 1) {
        if(context.connection) {
            XSetIOErrorHandler(prev_xioerror);
            prev_xioerror = NULL;

            XSetErrorHandler(prev_xerror);
            prev_xerror = NULL;

            XCloseDisplay(context.connection);
            context.connection = NULL;

            /*
                GLX needs to be unloaded after closing the display on nvidia because
                nvidia registers cleanup callbacks on exit, that uses the x11 display.
            */
            glx_context_deinit();
            mgl_gl_unload(&context.gl);
        }
    }

    if(init_count > 0)
        --init_count;
}

mgl_context* mgl_get_context(void) {
#ifndef NDEBUG
    if(init_count == 0) {
        fprintf(stderr, "mgl error: mgl_get_context was called before mgl_init\n");
        abort();
    }
#endif
    return &context;
}