#define _GNU_SOURCE 1
#include <string.h>
#include <stdio.h>
#include <err.h>
#include <errno.h>
#include "uname.h"
#include <lauxlib.h>
#include <lua.h>
#include <sys/utsname.h>

#define ERRBUF_SIZE 1024

static int l_numid(lua_State *L) {
    lua_Number x = luaL_checknumber(L, 1);
    printf("%f\n", x);
    
    lua_pushnumber(L, x);

    return 1;
}

/*
 * Add one
 */
long long plus_one(int x) {
    return x + 1;
}

static int l_plus_one(lua_State *L) {
    // argument number check is not conventional in lua?
    int argc = lua_gettop(L);
    if (argc != 1)
        return luaL_error(L, "Invalid number of argument");

    // Type check and get
    lua_Integer x = luaL_checkinteger(L, 1);

    lua_Integer result = plus_one(x);

    // Push the result
    lua_pushinteger(L, result);
    // How many elements from the top is return value
    return 1;
}

static int l_uname(lua_State *L) {
    struct utsname name;
    if (uname(&name)) {
        char errbuf[ERRBUF_SIZE];
        if (strerror_r(errno, errbuf, ERRBUF_SIZE))
            perror("Error while making error msg");
        return luaL_error(L, errbuf);
    }
    lua_newtable(L);
    lua_pushstring(L, "sysname");
    lua_pushstring(L, name.sysname);
    lua_settable(L, -3);
    lua_pushstring(L, "machine");
    lua_pushstring(L, name.machine);
    lua_settable(L, -3);
    lua_pushstring(L, "release");
    lua_pushstring(L, name.release);
    lua_settable(L, -3);
    lua_pushstring(L, "version");
    lua_pushstring(L, name.version);
    lua_settable(L, -3);
    return 1;
}

static const struct luaL_Reg llib_uname [] = {
    {"uname", l_uname},
    {"numid", l_numid},
    {"plusone", l_plus_one},
    {NULL, NULL},
};

// for `require`
int luaopen_uname(lua_State *L) {
    luaL_newlib(L, llib_uname);
    return 1;
}