GLFW Events for Lua

#include <GL/glfw3.h>
#include "lua.h"
#include "lj_obj.h"
#include "lauxlib.h"

lua_State *current_L;

void insert_simple_int_event(const char *type, const char *key, int value, GLFWwindow window) {
    lua_State *L = current_L;

    lua_createtable(L, 0, 3);

    lua_pushstring(L, "type");
    lua_pushstring(L, type);
    lua_rawset(L, -3);

    lua_pushstring(L, key);
    lua_pushinteger(L, value);
    lua_rawset(L, -3);

    lua_pushstring(L, "window");
    lua_pushinteger(L, (lua_Integer)window);
    lua_rawset(L, -3);

    lua_pushinteger(L, lua_objlen(L, -2) + 1);
    lua_insert(L, -2);
    lua_rawset(L, -3);
}

/*
  key will be the key identifier, action will be GLFW_PRESS or GLFW_RELEASE
*/
void handle_key_event(GLFWwindow window, int key, int action) {
    insert_simple_int_event((action == GLFW_PRESS) ? "keydown" : "keyup", "key", key, window);
}

/*
  char will be the unicode codepoint of the character typed
 */
void handle_char_event(GLFWwindow window, int chr) {
    insert_simple_int_event("char", "char", chr, window);
}

static int l_registerEventListeners(lua_State *L) {
    glfwSetKeyCallback(&handle_key_event);
    glfwSetCharCallback(&handle_char_event);
    return 0;
}

static int l_pollEvents(lua_State *L) {
    lua_newtable(L);
    current_L = L;
    glfwPollEvents();
    return 1;
}

static const struct luaL_Reg glfw_c [] = {
    {"registerEventListeners", l_registerEventListeners},
    {"pollEvents", l_pollEvents},
    {NULL, NULL}
};

int luaopen_c_glfw_c(lua_State *L) {
    luaL_register(L, "glfw_c", glfw_c);
    return 1;
}