/* jshint esversion: 6 */
"use strict";

const assert  = require('assert');

const lua     = require('./lua.js');
const lapi    = require('./lapi.js');
const lauxlib = require('./lauxlib.js');
const CT      = lua.constant_types;

const luaB_print = function(L) {
    let n = lapi.lua_gettop(L); /* number of arguments */
    let str = "";

    lapi.lua_getglobal(L, "tostring");
    for (let i = 1; i <= n; i++) {
        lapi.lua_pushvalue(L, -1);  /* function to be called */
        lapi.lua_pushvalue(L, i);  /* value to print */
        lapi.lua_call(L, 1, 1);
        let s = lapi.lua_tolstring(L, -1);
        if (s === null)
            throw new Error("'tostring' must return a string to 'print");
        if (i > 1) s = `\t${s}`;
        str = `${str}${s}`;
        lapi.lua_pop(L, 1);
    }

    console.log(str);
    return 0;
};

const luaB_tostring = function(L) {
    lauxlib.luaL_checkany(L, 1);
    lauxlib.luaL_tolstring(L, 1);

    return 1;
};

const luaB_getmetatable = function(L) {
    lauxlib.luaL_checkany(L, 1);
    if (!lapi.lua_getmetatable(L, 1)) {
        lapi.lua_pushnil(L);
        return 1;  /* no metatable */
    }
    lauxlib.luaL_getmetafield(L, 1, "__metatable");
    return 1;  /* returns either __metatable field (if present) or metatable */
};

const luaB_setmetatable = function(L) {
    let t = lapi.lua_type(L, 2);
    lauxlib.luaL_checktype(L, 1, CT.LUA_TTABLE);
    lauxlib.luaL_argcheck(L, t === CT.LUA_TNIL || t === CT.LUA_TTABLE, 2, "nil or table expected");
    if (lauxlib.luaL_getmetafield(L, 1, "__metatable") !== CT.LUA_TNIL)
        throw new Error("cannot change a protected metatable");
    lapi.lua_settop(L, 2);
    lapi.lua_setmetatable(L, 1);
    return 1;
};

const luaB_rawequal = function(L) {
    lauxlib.luaL_checkany(L, 1);
    lauxlib.luaL_checkany(L, 2);
    lapi.lua_pushboolean(L, lapi.lua_rawequal(L, 1, 2));
    return 1;
};

const luaB_rawget = function(L) {
    lauxlib.luaL_checktype(L, 1, CT.LUA_TTABLE);
    lauxlib.luaL_checkany(L, 2);
    lapi.lua_settop(L, 2);
    lapi.lua_rawget(L, 1);
    return 1;
};

const luaB_rawset = function(L) {
    lauxlib.luaL_checktype(L, 1, CT.LUA_TTABLE);
    lauxlib.luaL_checkany(L, 2);
    lauxlib.luaL_checkany(L, 3);
    lapi.lua_settop(L, 3);
    lapi.lua_rawset(L, 1);
    return 1;
};

const luaB_type = function(L) {
    let t = lapi.lua_type(L, 1);
    lauxlib.luaL_argcheck(L, t != CT.LUA_TNONE, 1, "value expected");
    lapi.lua_pushstring(L, lapi.lua_typename(L, t));
    return 1;
};

const luaB_error = function(L) {
    let level = lauxlib.luaL_optinteger(L, 2, 1);
    lapi.lua_settop(L, 1);
    if (lapi.lua_type(L, 1) === CT.LUA_TSTRING && level > 0) {
        lauxlib.luaL_where(L, level);  /* add extra information */
        lapi.lua_pushvalue(L, 1);
        lapi.lua_concat(L, 2);
    }
    return lapi.lua_error(L);
};

const base_funcs = {
    "collectgarbage": function () {},
    "print":          luaB_print,
    "tostring":       luaB_tostring,
    "getmetatable":   luaB_getmetatable,
    "setmetatable":   luaB_setmetatable,
    "rawequal":       luaB_rawequal,
    "rawset":         luaB_rawset,
    "rawget":         luaB_rawget,
    "type":           luaB_type,
    "error":          luaB_error
};

const luaopen_base = function(L) {
    /* open lib into global table */
    lapi.lua_pushglobaltable(L);
    lauxlib.luaL_setfuncs(L, base_funcs, 0);
    /* set global _G */
    lapi.lua_pushvalue(L, -1);
    lapi.lua_setfield(L, -2, "_G");
    /* set global _VERSION */
    lapi.lua_pushliteral(L, lua.LUA_VERSION);
    lapi.lua_setfield(L, -2, "_VERSION");
    return 1;
};

module.exports.luaopen_base      = luaopen_base;