/*
 * Copyright (c) 1985, 1987, 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)date.c   8.2 (Berkeley) 4/28/95
 * $FreeBSD: src/bin/date/date.c,v 1.47 2005/01/10 08:39:21 imp Exp $
 */

#include <sys/param.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <locale.h>
#include <libutil.h>
#include <utmpx.h>

#include "vary.h"

#ifndef TM_YEAR_BASE
#define TM_YEAR_BASE    1900
#endif

static time_t tval;

static void badformat(void);
static void setthetime(const char *, const char *, int);
static void usage(void);

static const struct iso8601_fmt {
        const char *refname;
        const char *format;
} iso8601_fmts[] = {
        { "date", "%Y-%m-%d" },
        { "hours", "%Y-%m-%dT%H" },
        { "minutes", "%Y-%m-%dT%H:%M" },
        { "seconds", "%Y-%m-%dT%H:%M:%S" },
};
static const struct iso8601_fmt *iso8601_selected;

static const char *rfc2822_format = "%a, %d %b %Y %T %z";

int
main(int argc, char **argv)
{
        int ch, rflag;
        int Iflag, jflag, Rflag;
        const char *format;
        char buf[1024], tzbuf[8];
        char *fmt;
        char *tmp;
        struct vary *v;
        const struct vary *badv;
        struct tm lt;
        size_t i;

        v = NULL;
        fmt = NULL;
        setlocale(LC_TIME, "");
        rflag = 0;
        Iflag = jflag = Rflag = 0;
        while ((ch = getopt(argc, argv, "d:f:I::jnRr:uv:")) != -1) {
                switch (ch) {
                case 'f':
                        fmt = optarg;
                        break;
                case 'I':               /* ISO 8601 datetime format */
                        if (Rflag)
                                errx(1, "multiple output formats specified");
                        Iflag = 1;
                        if (optarg == NULL) {
                                iso8601_selected = iso8601_fmts;
                                break;
                        }
                        for (i = 0; i < nitems(iso8601_fmts); i++) {
                                if (strncmp(optarg, iso8601_fmts[i].refname,
                                            strlen(optarg)) == 0)
                                        break;
                        }
                        if (i == nitems(iso8601_fmts))
                                errx(1, "invalid argument '%s' for -I", optarg);
                        iso8601_selected = &iso8601_fmts[i];
                        break;
                case 'j':
                        jflag = 1;      /* don't set time */
                        break;
                case 'n':               /* don't set network */
                        break;
                case 'R':               /* RFC 2822 datetime format */
                        if (Iflag)
                                errx(1, "multiple output formats specified");
                        Rflag = 1;
                        break;
                case 'r':               /* user specified seconds */
                        rflag = 1;
                        tval = strtoll(optarg, &tmp, 0);
                        if (*tmp != 0)
                                usage();
                        break;
                case 'u':               /* do everything in UTC */
                        if (setenv("TZ", "UTC0", 1) != 0)
                                err(1, "setenv: cannot set TZ=UTC0");
                        break;
                case 'd':
                case 'v':
                        if (strncmp(optarg, "TZ=", 3) == 0) {
                                tmp = strdup(optarg);
                                size_t tzlen;

                                for (tzlen = 0; !isspace(tmp[tzlen]); ++tzlen)
                                        ;
                                if (tmp[0] == '"' && tmp[tzlen - 1] == '"') {
                                        tmp[tzlen - 1] = 0;
                                        setenv("TZ", tmp + 1, 1);
                                } else {
                                        tmp[tzlen] = 0;
                                        setenv("TZ", tmp, 1);
                                }
                                while (isspace(tmp[tzlen]))
                                        ++tzlen;
                                if (tmp[tzlen])
                                        v = vary_append(v, optarg + tzlen);
                        } else {
                                v = vary_append(v, optarg);
                        }
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (!rflag && time(&tval) == -1)
                err(1, "time");

        format = "%+";

        if (Rflag)
                format = rfc2822_format;
        if (Iflag)
                format = iso8601_selected->format;

        /* allow the operands in any order */
        if (*argv && **argv == '+') {
                if (Iflag || Rflag)
                        errx(1, "multiple output formats specified");
                format = *argv + 1;
                ++argv;
        }

        if (*argv) {
                setthetime(fmt, *argv, jflag);
                ++argv;
        } else if (fmt != NULL)
                usage();

        if (*argv && **argv == '+') {
                if (Iflag || Rflag)
                        errx(1, "multiple output formats specified");
                format = *argv + 1;
        }

        badv = vary_apply(v, tval, &lt);
        if (badv) {
                fprintf(stderr, "%s: Cannot apply date adjustment\n",
                        badv->arg);
                vary_destroy(v);
                usage();
        }
        vary_destroy(v);

        if (format == rfc2822_format) {
                /*
                 * When using RFC 2822 datetime format, don't honor the
                 * locale.
                 */
                setlocale(LC_TIME, "C");
        }

        strftime(buf, sizeof(buf), format, &lt);
        if (Iflag && iso8601_selected > iso8601_fmts) {
                strftime(tzbuf, sizeof(tzbuf), "%z", &lt);
                memmove(&tzbuf[4], &tzbuf[3], 3);
                tzbuf[3] = ':';
                strlcat(buf, tzbuf, sizeof(buf));
        }
        printf("%s\n", buf);
        if (fflush(stdout) != 0)
                err(1, "stdout");
        exit(EXIT_SUCCESS);
}

#define ATOI2(s)        ((s) += 2, ((s)[-2] - '0') * 10 + ((s)[-1] - '0'))

static void
setthetime(const char *fmt, const char *p, int jflag)
{
        struct tm *lt;
        struct timeval tv;
        const char *dot, *t;
        int century;

        if (fmt != NULL) {
                lt = localtime(&tval);
                t = strptime(p, fmt, lt);
                if (t == NULL) {
                        fprintf(stderr, "Failed conversion of ``%s''"
                                " using format ``%s''\n", p, fmt);
                        badformat();
                } else if (*t != '\0')
                        fprintf(stderr, "Warning: Ignoring %ld extraneous"
                                " characters in date string (%s)\n",
                                (long) strlen(t), t);
        } else {
                for (t = p, dot = NULL; *t; ++t) {
                        if (isdigit(*t))
                                continue;
                        if (*t == '.' && dot == NULL) {
                                dot = t;
                                continue;
                        }
                        badformat();
                }

                lt = localtime(&tval);

                if (dot != NULL) {                      /* .ss */
                        dot++; /* *dot++ = '\0'; */
                        if (strlen(dot) != 2)
                                badformat();
                        lt->tm_sec = ATOI2(dot);
                        if (lt->tm_sec > 61)
                                badformat();
                } else
                        lt->tm_sec = 0;

                century = 0;
                /* if p has a ".ss" field then let's pretend it's not there */
                switch (strlen(p) - ((dot != NULL) ? 3 : 0)) {
                case 12:                                /* cc */
                        lt->tm_year = ATOI2(p) * 100 - TM_YEAR_BASE;
                        century = 1;
                        /* FALLTHROUGH */
                case 10:                                /* yy */
                        if (century)
                                lt->tm_year += ATOI2(p);
                        else {                          /* hack for 2000 ;-} */
                                lt->tm_year = ATOI2(p);
                                if (lt->tm_year < 69)
                                        lt->tm_year += 2000 - TM_YEAR_BASE;
                                else
                                        lt->tm_year += 1900 - TM_YEAR_BASE;
                        }
                        /* FALLTHROUGH */
                case 8:                                 /* mm */
                        lt->tm_mon = ATOI2(p);
                        if (lt->tm_mon > 12)
                                badformat();
                        --lt->tm_mon;           /* time struct is 0 - 11 */
                        /* FALLTHROUGH */
                case 6:                                 /* dd */
                        lt->tm_mday = ATOI2(p);
                        if (lt->tm_mday > 31)
                                badformat();
                        /* FALLTHROUGH */
                case 4:                                 /* HH */
                        lt->tm_hour = ATOI2(p);
                        if (lt->tm_hour > 23)
                                badformat();
                        /* FALLTHROUGH */
                case 2:                                 /* MM */
                        lt->tm_min = ATOI2(p);
                        if (lt->tm_min > 59)
                                badformat();
                        break;
                default:
                        badformat();
                }
        }

        /* Let mktime() decide whether summer time is in effect. */
        lt->tm_isdst = -1;

        /* convert broken-down time to GMT clock time */
        if ((tval = mktime(lt)) == -1)
                errx(1, "nonexistent time");

        if (!jflag) {
                logwtmpx("|", "date", "", 0, OLD_TIME);
                tv.tv_sec = tval;
                tv.tv_usec = 0;
                if (settimeofday(&tv, NULL))
                        err(1, "settimeofday (timeval)");
                logwtmpx("{", "date", "", 0, NEW_TIME);

                if ((p = getlogin()) == NULL)
                        p = "???";
                syslog(LOG_AUTH | LOG_NOTICE, "date set by %s", p);
        }
}

static void
badformat(void)
{
        warnx("illegal time format");
        usage();
}

static void
usage(void)
{
        fprintf(stderr, "%s\n%s\n",
            "usage: date [-jnRu] [-r seconds] [-v[+|-]val[ymwdHMS]] ... ",
            "            "
            "[-I [date | hours | minutes | seconds]]"
            "            "
            "[-f fmt date | [[[[[cc]yy]mm]dd]HH]MM[.ss]] [+format]");
        exit(1);
}