/*
** $Id: loslib.c,v 1.19.1.3 2008/01/18 16:38:18 roberto Exp $
** Standard Operating System library
** See Copyright Notice in lua.h
*/

#include <errno.h>
#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define loslib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

static int os_pushresult(lua_State *L, int i, const char *filename)
{
    int en = errno; /* calls to Lua API may change this value */
    if (i) {
        lua_pushboolean(L, 1);
        return 1;
    }
    else {
        lua_pushnil(L);
        lua_pushfstring(L, "%s: %s", filename, strerror(en));
        lua_pushinteger(L, en);
        return 3;
    }
}

static int os_execute(lua_State *L)
{
    lua_pushinteger(L, system(luaL_optstring(L, 1, NULL)));
    return 1;
}

static int os_remove(lua_State *L)
{
    const char *filename = luaL_checkstring(L, 1);
    return os_pushresult(L, remove(filename) == 0, filename);
}

static int os_rename(lua_State *L)
{
    const char *fromname = luaL_checkstring(L, 1);
    const char *toname = luaL_checkstring(L, 2);
    return os_pushresult(L, rename(fromname, toname) == 0, fromname);
}

static int os_tmpname(lua_State *L)
{
    char buff[LUA_TMPNAMBUFSIZE];
    int err;
    lua_tmpnam(buff, err);
    if (err)
        return luaL_error(L, "unable to generate a unique filename");
    lua_pushstring(L, buff);
    return 1;
}

static int os_getenv(lua_State *L)
{
    lua_pushstring(L, getenv(luaL_checkstring(L, 1))); /* if NULL push nil */
    return 1;
}

static int os_clock(lua_State *L)
{
    lua_pushnumber(L, ((lua_Number)clock()) / (lua_Number)CLOCKS_PER_SEC);
    return 1;
}

/*
** {======================================================
** Time/Date operations
** { year=%Y, month=%m, day=%d, hour=%H, min=%M, sec=%S,
**   wday=%w+1, yday=%j, isdst=? }
** =======================================================
*/

static void setfield(lua_State *L, const char *key, int value)
{
    lua_pushinteger(L, value);
    lua_setfield(L, -2, key);
}

static void setboolfield(lua_State *L, const char *key, int value)
{
    if (value < 0) /* undefined? */
        return;    /* does not set field */
    lua_pushboolean(L, value);
    lua_setfield(L, -2, key);
}

static int getboolfield(lua_State *L, const char *key)
{
    int res;
    lua_getfield(L, -1, key);
    res = lua_isnil(L, -1) ? -1 : lua_toboolean(L, -1);
    lua_pop(L, 1);
    return res;
}

static int getfield(lua_State *L, const char *key, int d)
{
    int res;
    lua_getfield(L, -1, key);
    if (lua_isnumber(L, -1))
        res = (int)lua_tointeger(L, -1);
    else {
        if (d < 0)
            return luaL_error(L, "field " LUA_QS " missing in date table", key);
        res = d;
    }
    lua_pop(L, 1);
    return res;
}

static int os_date(lua_State *L)
{
    const char *s = luaL_optstring(L, 1, "%c");
    time_t t = luaL_opt(L, (time_t)luaL_checknumber, 2, time(NULL));
    struct tm *stm;
    if (*s == '!') { /* UTC? */
        stm = gmtime(&t);
        s++; /* skip `!' */
    }
    else
        stm = localtime(&t);
    if (stm == NULL) /* invalid date? */
        lua_pushnil(L);
    else if (strcmp(s, "*t") == 0) {
        lua_createtable(L, 0, 9); /* 9 = number of fields */
        setfield(L, "sec", stm->tm_sec);
        setfield(L, "min", stm->tm_min);
        setfield(L, "hour", stm->tm_hour);
        setfield(L, "day", stm->tm_mday);
        setfield(L, "month", stm->tm_mon + 1);
        setfield(L, "year", stm->tm_year + 1900);
        setfield(L, "wday", stm->tm_wday + 1);
        setfield(L, "yday", stm->tm_yday + 1);
        setboolfield(L, "isdst", stm->tm_isdst);
    }
    else {
        char cc[3];
        luaL_Buffer b;
        cc[0] = '%';
        cc[2] = '\0';
        luaL_buffinit(L, &b);
        for (; *s; s++) {
            if (*s != '%' || *(s + 1) == '\0') /* no conversion specifier? */
                luaL_addchar(&b, *s);
            else {
                size_t reslen;
                char buff
                    [200]; /* should be big enough for any conversion result */
                cc[1] = *(++s);
                reslen = strftime(buff, sizeof(buff), cc, stm);
                luaL_addlstring(&b, buff, reslen);
            }
        }
        luaL_pushresult(&b);
    }
    return 1;
}

static int os_time(lua_State *L)
{
    time_t t;
    if (lua_isnoneornil(L, 1)) /* called without args? */
        t = time(NULL);        /* get current time */
    else {
        struct tm ts;
        luaL_checktype(L, 1, LUA_TTABLE);
        lua_settop(L, 1); /* make sure table is at the top */
        ts.tm_sec = getfield(L, "sec", 0);
        ts.tm_min = getfield(L, "min", 0);
        ts.tm_hour = getfield(L, "hour", 12);
        ts.tm_mday = getfield(L, "day", -1);
        ts.tm_mon = getfield(L, "month", -1) - 1;
        ts.tm_year = getfield(L, "year", -1) - 1900;
        ts.tm_isdst = getboolfield(L, "isdst");
        t = mktime(&ts);
    }
    if (t == (time_t)(-1))
        lua_pushnil(L);
    else
        lua_pushnumber(L, (lua_Number)t);
    return 1;
}

static int os_difftime(lua_State *L)
{
    lua_pushnumber(L, difftime((time_t)(luaL_checknumber(L, 1)),
                               (time_t)(luaL_optnumber(L, 2, 0))));
    return 1;
}

/* }====================================================== */

static int os_setlocale(lua_State *L)
{
    static const int cat[] = {LC_ALL,      LC_COLLATE, LC_CTYPE,
                              LC_MONETARY, LC_NUMERIC, LC_TIME};
    static const char *const catnames[] = {
        "all", "collate", "ctype", "monetary", "numeric", "time", NULL};
    const char *l = luaL_optstring(L, 1, NULL);
    int op = luaL_checkoption(L, 2, "all", catnames);
    lua_pushstring(L, setlocale(cat[op], l));
    return 1;
}

static int os_exit(lua_State *L) { exit(luaL_optint(L, 1, EXIT_SUCCESS)); }

static const luaL_Reg syslib[] = {
    {"clock", os_clock},         {"date", os_date},
    {"difftime", os_difftime},   {"execute", os_execute},
    {"exit", os_exit},           {"getenv", os_getenv},
    {"remove", os_remove},       {"rename", os_rename},
    {"setlocale", os_setlocale}, {"time", os_time},
    {"tmpname", os_tmpname},     {NULL, NULL}};

/* }====================================================== */

LUALIB_API int luaopen_os(lua_State *L)
{
    luaL_register(L, LUA_OSLIBNAME, syslib);
    return 1;
}
