#include "luastack.hpp"

LuaSlot LuaRegistry(LUA_REGISTRYINDEX);
LuaSlot LuaGlobals(LUA_GLOBALSINDEX);

void LuaStack::count_slots_finalize(int narg, int nvar, int nret) {
    narg_ = narg;
    nret_ = nret;
    nvar_ = nvar;
    ngap_ = nret - nvar - narg;
    if (ngap_ < 0) ngap_ = 0;

    int argtop = lua_gettop(L_);
    argpos_ = argtop + 1 - narg_;
    gappos_ = argpos_ + narg_;
    varpos_ = gappos_ + ngap_;
    retpos_ = varpos_ + nvar_;

    rettop_ = retpos_ + nret_ - 1;
    finaltop_ = argpos_ + nret_ - 1;
}

void LuaStack::clear_frame() {
    lua_settop(L_, varpos_ - 1);
    for (int i = 0; i < nvar_ + nret_; i++) {
        lua_pushnil(L_);
    }
}

int LuaStack::result() {
    lua_settop(L_, rettop_);
    int i = finaltop_;
    for (int j = 0; j < nret_; j++) {
        lua_replace(L_, i);
        i -= 1;
    }
    lua_settop(L_, finaltop_);
    return nret_;
}

void LuaStack::reg(lua_State *L, const char *classname, const char *funcname, lua_CFunction fn) {
    int top = lua_gettop(L);
    lua_pushvalue(L, LUA_GLOBALSINDEX);
    luaL_Reg reg;
    reg.name = funcname;
    reg.func = fn;
    luaL_register(L, classname, &reg);
    lua_settop(L, top);
}

void LuaStack::setnil(LuaSlot target) const {
    lua_pushnil(L_);
    lua_replace(L_, target);
}

void LuaStack::setboolean(LuaSlot target, bool b) const {
    lua_pushboolean(L_, b ? 1 : 0);
    lua_replace(L_, target);
}

void LuaStack::setboolean(LuaSlot target, int b) const {
    lua_pushboolean(L_, b);
    lua_replace(L_, target);
}

void LuaStack::setstring(LuaSlot target, const char *str) const {
    lua_pushstring(L_, str);
    lua_replace(L_, target);
}

void LuaStack::setstring(LuaSlot target, const std::string &str) const {
    lua_pushlstring(L_, str.c_str(), str.size());
    lua_replace(L_, target);
}

void LuaStack::setnumber(LuaSlot target, double value) const {
    lua_pushnumber(L_, value);
    lua_replace(L_, target);
}

std::string LuaStack::tostring(LuaSlot s) const {
    size_t len;
    const char *str = lua_tolstring(L_, s, &len);
    return std::string(str, len);
}

std::string LuaStack::checkstring(LuaSlot s) const {
    size_t len;
    const char *str = luaL_checklstring(L_, s, &len);
    return std::string(str, len);
}

void LuaStack::clearmetatable(LuaSlot tab) const {
    lua_pushnil(L_);
    lua_setmetatable(L_, tab);
}

void LuaStack::setmetatable(LuaSlot tab, LuaSlot mt) const {
    lua_pushvalue(L_, mt);
    lua_setmetatable(L_, tab);
}

void LuaStack::checknometa(LuaSlot index) const {
    if (lua_istable(L_, index)) {
        if (!lua_getmetatable(L_, index)) {
            return;
        }
    }
    luaL_error(L_, "expected simple table with no metatable");
}

int LuaStack::next(LuaSlot tab, LuaSlot key, LuaSlot value) const {
    lua_pushvalue(L_, key);
    int ret = lua_next(L_, tab);
    if (ret != 0) {
        lua_replace(L_, value);
        lua_replace(L_, key);
    }
    return ret;
}

void LuaStack::newtable(LuaSlot target) const {
    lua_newtable(L_);
    lua_replace(L_, target);
}