/*      $OpenBSD: leave.c,v 1.20 2020/01/27 01:05:28 tedu Exp $ */
/*      $NetBSD: leave.c,v 1.4 1995/07/03 16:50:13 phil Exp $   */

/*
 * Copyright (c) 1980, 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.
 */

#include <sys/time.h>
#include <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static __dead void      usage(void);
static void             doalarm(u_int secs);

#define SECOND  1
#define MINUTE  (SECOND * 60)
#define FIVEMIN (5 * MINUTE)
#define HOUR    (MINUTE * 60)

/*
 * leave [[+]hhmm]
 *
 * Reminds you when you have to leave.
 * Leave prompts for input and goes away if you hit return.
 * It nags you like a mother hen.
 */
int
main(int argc, char *argv[])
{
        u_int secs;
        int hours, minutes;
        char c, *cp;
        struct tm *t;
        time_t now;
        int plusnow = 0, twentyfour;
        char buf[50];

        if (pledge("stdio proc", NULL) == -1)
                err(1, "pledge");

        if (setvbuf(stdout, NULL, _IOLBF, 0) != 0)
                errx(1, "Cannot set stdout to line buffered.");

        if (argc < 2) {
                (void)fputs("When do you have to leave? ", stdout);
                cp = fgets(buf, sizeof(buf), stdin);
                if (cp == NULL || *cp == '\n')
                        return 0;
        } else if (argc > 2)
                usage();
        else
                cp = argv[1];

        if (*cp == '+') {
                plusnow = 1;
                ++cp;
        }

        if (!plusnow && strlen(cp) != 4)
                usage();

        for (hours = 0; (c = *cp) && c != '\n'; ++cp) {
                if (!isdigit((unsigned char)c))
                        usage();
                hours = hours * 10 + (c - '0');
        }
        minutes = hours % 100;
        hours /= 100;
        /* determine 24 hours mode */
        twentyfour = hours > 12;

        if (minutes < 0 || minutes > 59)
                usage();
        if (plusnow)
                secs = (hours * HOUR) + (minutes * MINUTE);
        else {
                if (hours > 23)
                        usage();
                (void)time(&now);
                t = localtime(&now);
                while (t->tm_hour > hours || 
                    (t->tm_hour == hours && t->tm_min >= minutes)) {
                        if (twentyfour)
                                hours += 24;
                        else
                                hours += 12;
                }

                secs = (hours - t->tm_hour) * HOUR;
                secs += (minutes - t->tm_min) * MINUTE;
                secs -= t->tm_sec;      /* aim for beginning of minute */
        }
        doalarm(secs);
        return 0;
}

static void
doalarm(u_int secs)
{
        int bother;
        time_t daytime;
        pid_t pid;

        switch (pid = fork()) {
        case 0:
                break;
        case -1:
                err(1, "Fork failed");
                /* NOTREACHED */
        default:
                (void)time(&daytime);
                daytime += secs;
                printf("Alarm set for %.16s. (pid %ld)\n",
                    ctime(&daytime), (long)pid);
                exit(0);
        }
        sleep(2);                       /* let parent print set message */

        /*
         * if write fails, we've lost the terminal through someone else
         * causing a vhangup by logging in.
         */
        if (secs >= FIVEMIN) {
                sleep(secs - FIVEMIN);
                if (puts("\a\aYou have to leave in 5 minutes.") == EOF)
                        exit(0);
                secs = FIVEMIN;
        }

        if (secs >= MINUTE) {
                sleep(secs - MINUTE);
                if (puts("\a\aJust one more minute!") == EOF)
                        exit(0);
                secs = MINUTE;
        }

        sleep(secs);

        for (bother = 10; bother--;) {
                if (puts("\a\aTime to leave!") == EOF)
                        exit(0);
                if (bother)
                        sleep(MINUTE);
        }

        puts("\a\aThat was the last time I'll tell you.  Bye.");
        exit(0);
}

static __dead void
usage(void)
{
        fprintf(stderr, "usage: leave [[+]hhmm]\n");
        exit(1);
}