#include <lauxlib.h>

#include "compat.h"

static int lua_absindex (lua_State *L, int i) {
  if (i < 0 && i > LUA_REGISTRYINDEX)
    i += lua_gettop(L) + 1;
  return i;
}

int luaL_getsubtable (lua_State *L, int i, const char *name) {
  int abs_i = lua_absindex(L, i);
  luaL_checkstack(L, 3, "not enough stack slots");
  lua_pushstring(L, name);
  lua_gettable(L, abs_i);
  if (lua_istable(L, -1))
    return 1;
  lua_pop(L, 1);
  lua_newtable(L);
  lua_pushstring(L, name);
  lua_pushvalue(L, -2);
  lua_settable(L, abs_i);
  return 0;
}

void luaL_requiref (lua_State *L, const char *modname, lua_CFunction openf, int glb) {
  luaL_checkstack(L, 3, "not enough stack slots available");
  luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
  lua_getfield(L, -1, modname);
  if (lua_isnil(L, -1)) {
    lua_pop(L, 1);
    lua_pushcfunction(L, openf);
    lua_pushstring(L, modname);
    lua_call(L, 1, 1);
    lua_pushvalue(L, -1);
    lua_setfield(L, -3, modname);
  }
  if (glb) {
    lua_pushvalue(L, -1);
    lua_setglobal(L, modname);
  }
  lua_replace(L, -2);
}

void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
  luaL_checkstack(L, nup+1, "too many upvalues");
  for (; l->name != NULL; l++) {  /* fill the table with given functions */
    int i;
    lua_pushstring(L, l->name);
    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
      lua_pushvalue(L, -(nup + 1));
    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
    lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
  }
  lua_pop(L, nup);  /* remove upvalues */
}


void luaL_setmetatable (lua_State *L, const char *tname) {
  luaL_checkstack(L, 1, "not enough stack slots");
  luaL_getmetatable(L, tname);
  lua_setmetatable(L, -2);
}