#include <lua.h>
#include <string.h>
#include <stdio.h>
#include <X11/Xatom.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xfixes.h>
#include <X11/extensions/XInput2.h>
#include <X11/extensions/Xrandr.h>
#include <threads.h>

#define DEBUG

#ifdef DEBUG
static FILE *log_file = NULL;
static void dbg(const char *fmt, ...) {
    va_list args;
    if (log_file == NULL) {
        log_file = fopen("/home/mutzi/xdpb.txt", "a+");
    }
    va_start(args, fmt);
    vfprintf(log_file, fmt, args);
    va_end(args);
    fflush(log_file);
}
#else
static inline void dbg(const char *fmt, ...) {}
#endif

static struct {
    Display *display;
    Window root_window;

    int have_barriers;
    PointerBarrier t, b, l, r;
} globals;

static PointerBarrier mkbar(int x1, int y1, int x2, int y2, int directions) {
    PointerBarrier pb = XFixesCreatePointerBarrier(globals.display, globals.root_window, x1, y1, x2, y2, directions, 0, NULL);
    dbg("mkbar(%d, %d, %d, %d, %d) = %lu\n", x1, y1, x2, y2, directions, pb);
    return pb;
}

static int toggle_constrain(lua_State *L) {
    dbg("Toggling constrain\n");
    if (globals.have_barriers == 0) {
        lua_getfield(L, -1, "x");
        lua_getfield(L, -2, "y");
        lua_getfield(L, -3, "width");
        lua_getfield(L, -4, "height");

        int x = (int)lua_tointeger(L, -4), y = (int)lua_tointeger(L, -3), w = (int)lua_tointeger(L, -2), h = (int)lua_tointeger(L, -1);

        dbg("Window x: %d y: %d w: %d h: %d\n", x, y, w, h);

        globals.t = mkbar(x - 1, y, x + w + 1, y, BarrierPositiveY);
        globals.b = mkbar(x - 1, y + h, x + w + 1, y + h, BarrierNegativeY);
        globals.l = mkbar(x, y - 1, x, y + h + 1, BarrierPositiveX);
        globals.r = mkbar(x + w, y - 1, x + w, y + h + 1, BarrierNegativeX);

        globals.have_barriers = 1;
        char msg_format[200];
        lua_getfield(L, -5, "name");
        snprintf(msg_format, 200, "Constraining mouse to %s", lua_tostring(L, -1));
        lua_pushstring(L, msg_format);
    } else {
        XFixesDestroyPointerBarrier(globals.display, globals.t);
        XFixesDestroyPointerBarrier(globals.display, globals.b);
        XFixesDestroyPointerBarrier(globals.display, globals.l);
        XFixesDestroyPointerBarrier(globals.display, globals.r);

        globals.have_barriers = 0;
        lua_pushstring(L, "Released mouse");
    }
    XSync(globals.display, 0);
    return 1;
}

int luaopen_libconstrain(lua_State *L) {
    dbg("Constrain opened\n");
    globals.have_barriers = 0;
    globals.display = XOpenDisplay(NULL);
    globals.root_window = XDefaultRootWindow(globals.display);
    lua_newtable(L);
    lua_pushcfunction(L, toggle_constrain);
    lua_setfield(L, -2, "toggle");
    return 1;
}