/*      $OpenBSD: seq.c,v 1.8 2023/06/13 21:10:41 millert Exp $ */

/*-
 * Copyright (c) 2005 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Brian Ginsbach.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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 <ctype.h>
#include <err.h>
#include <errno.h>
#include <getopt.h>
#include <math.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define VERSION "1.0"
#define ZERO    '0'
#define SPACE   ' '

#define MAXIMUM(a, b)   (((a) < (b))? (b) : (a))
#define ISSIGN(c)       ((int)(c) == '-' || (int)(c) == '+')
#define ISEXP(c)        ((int)(c) == 'e' || (int)(c) == 'E')
#define ISODIGIT(c)     ((int)(c) >= '0' && (int)(c) <= '7')

/* Globals */

static const char *decimal_point = "."; /* default */
static char default_format[] = { "%g" };        /* default */

static const struct option long_opts[] = {
        {"format",      required_argument,      NULL, 'f'},
        {"help",        no_argument,            NULL, 'h'},
        {"separator",   required_argument,      NULL, 's'},
        {"version",     no_argument,            NULL, 'v'},
        {"equal-width", no_argument,            NULL, 'w'},
        {NULL,          no_argument,            NULL, 0}
};

/* Prototypes */

static double e_atof(const char *);

static int decimal_places(const char *);
static int numeric(const char *);
static int valid_format(const char *);

static char *generate_format(double, double, double, int, char);

static __dead void usage(int error);

/*
 * The seq command will print out a numeric sequence from 1, the default,
 * to a user specified upper limit by 1.  The lower bound and increment
 * maybe indicated by the user on the command line.  The sequence can
 * be either whole, the default, or decimal numbers.
 */
int
main(int argc, char *argv[])
{
        int c = 0;
        int equalize = 0;
        double first = 1.0;
        double last = 0.0;
        double incr = 0.0;
        double prev = 0.0;
        double cur, step;
        struct lconv *locale;
        char *fmt = NULL;
        const char *sep = "\n";
        const char *term = "\n";
        char *cur_print, *last_print, *prev_print;
        char pad = ZERO;

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

        /* Determine the locale's decimal point. */
        locale = localeconv();
        if (locale && locale->decimal_point && locale->decimal_point[0] != '\0')
                decimal_point = locale->decimal_point;

        /*
         * Process options, but handle negative numbers separately
         * least they trip up getopt(3).
         */
        while ((optind < argc) && !numeric(argv[optind]) &&
            (c = getopt_long(argc, argv, "+f:s:w", long_opts, NULL)) != -1) {

                switch (c) {
                case 'f':       /* format (plan9/GNU) */
                        fmt = optarg;
                        equalize = 0;
                        break;
                case 's':       /* separator (GNU) */
                        sep = optarg;
                        break;
                case 'v':       /* version (GNU) */
                        printf("seq version %s\n", VERSION);
                        return 0;
                case 'w':       /* equal width (plan9/GNU) */
                        if (fmt == NULL) {
                                if (equalize++)
                                        pad = SPACE;
                        }
                        break;
                case 'h':       /* help (GNU) */
                        usage(0);
                        break;
                default:
                        usage(1);
                        break;
                }
        }

        argc -= optind;
        argv += optind;
        if (argc < 1 || argc > 3)
                usage(1);

        last = e_atof(argv[argc - 1]);

        if (argc > 1)
                first = e_atof(argv[0]);

        if (argc > 2) {
                incr = e_atof(argv[1]);
                /* Plan 9/GNU don't do zero */
                if (incr == 0.0)
                        errx(1, "zero %screment", (first < last) ? "in" : "de");
        }

        /* default is one for Plan 9/GNU work alike */
        if (incr == 0.0)
                incr = (first < last) ? 1.0 : -1.0;

        if (incr <= 0.0 && first < last)
                errx(1, "needs positive increment");

        if (incr >= 0.0 && first > last)
                errx(1, "needs negative decrement");

        if (fmt != NULL) {
                if (!valid_format(fmt))
                        errx(1, "invalid format string: `%s'", fmt);
                /*
                 * XXX to be bug for bug compatible with Plan 9 add a
                 * newline if none found at the end of the format string.
                 */
        } else
                fmt = generate_format(first, incr, last, equalize, pad);

        for (step = 1, cur = first; incr > 0 ? cur <= last : cur >= last;
            cur = first + incr * step++) {
                if (cur != first)
                        fputs(sep, stdout);
                printf(fmt, cur);
                prev = cur;
        }

        /*
         * Did we miss the last value of the range in the loop above?
         *
         * We might have, so check if the printable version of the last
         * computed value ('cur') and desired 'last' value are equal.  If
         * they are equal after formatting truncation, but 'cur' and 'prev'
         * are different, it means the exit condition of the loop held true
         * due to a rounding error and we still need to print 'last'.
         */
        if (asprintf(&cur_print, fmt, cur) == -1 ||
            asprintf(&last_print, fmt, last) == -1 ||
            asprintf(&prev_print, fmt, prev) == -1)
                err(1, "asprintf");
        if (strcmp(cur_print, last_print) == 0 &&
            strcmp(cur_print, prev_print) != 0) {
                if (cur != first)
                        fputs(sep, stdout);
                fputs(last_print, stdout);
        }
        free(cur_print);
        free(last_print);
        free(prev_print);

        fputs(term, stdout);

        return 0;
}

/*
 * numeric - verify that string is numeric
 */
static int
numeric(const char *s)
{
        int seen_decimal_pt, decimal_pt_len;

        /* skip any sign */
        if (ISSIGN((unsigned char)*s))
                s++;

        seen_decimal_pt = 0;
        decimal_pt_len = strlen(decimal_point);
        while (*s) {
                if (!isdigit((unsigned char)*s)) {
                        if (!seen_decimal_pt &&
                            strncmp(s, decimal_point, decimal_pt_len) == 0) {
                                s += decimal_pt_len;
                                seen_decimal_pt = 1;
                                continue;
                        }
                        if (ISEXP((unsigned char)*s)) {
                                s++;
                                if (ISSIGN((unsigned char)*s) ||
                                    isdigit((unsigned char)*s)) {
                                        s++;
                                        continue;
                                }
                        }
                        break;
                }
                s++;
        }
        return *s == '\0';
}

/*
 * valid_format - validate user specified format string
 */
static int
valid_format(const char *fmt)
{
        unsigned conversions = 0;

        while (*fmt != '\0') {
                /* scan for conversions */
                if (*fmt != '%') {
                        fmt++;
                        continue;
                }
                fmt++;

                /* allow %% but not things like %10% */
                if (*fmt == '%') {
                        fmt++;
                        continue;
                }

                /* flags */
                while (*fmt != '\0' && strchr("#0- +'", *fmt)) {
                        fmt++;
                }

                /* field width */
                while (*fmt != '\0' && strchr("0123456789", *fmt)) {
                        fmt++;
                }

                /* precision */
                if (*fmt == '.') {
                        fmt++;
                        while (*fmt != '\0' && strchr("0123456789", *fmt)) {
                                fmt++;
                        }
                }

                /* conversion */
                switch (*fmt) {
                case 'A':
                case 'a':
                case 'E':
                case 'e':
                case 'F':
                case 'f':
                case 'G':
                case 'g':
                        /* floating point formats are accepted */
                        conversions++;
                        break;
                default:
                        /* anything else is not */
                        return 0;
                }
        }

        /* PR 236347 -- user format strings must have a conversion */
        return conversions == 1;
}

/*
 * e_atof - convert an ASCII string to a double
 *      exit if string is not a valid double, or if converted value would
 *      cause overflow or underflow
 */
static double
e_atof(const char *num)
{
        char *endp;
        double dbl;

        errno = 0;
        dbl = strtod(num, &endp);

        if (errno == ERANGE)
                /* under or overflow */
                err(2, "%s", num);
        else if (*endp != '\0')
                /* "junk" left in number */
                errx(2, "invalid floating point argument: %s", num);

        /* zero shall have no sign */
        if (dbl == -0.0)
                dbl = 0;
        return dbl;
}

/*
 * decimal_places - count decimal places in a number (string)
 */
static int
decimal_places(const char *number)
{
        int places = 0;
        char *dp;

        /* look for a decimal point */
        if ((dp = strstr(number, decimal_point))) {
                dp += strlen(decimal_point);

                while (isdigit((unsigned char)*dp++))
                        places++;
        }
        return places;
}

/*
 * generate_format - create a format string
 *
 * XXX to be bug for bug compatible with Plan9 and GNU return "%g"
 * when "%g" prints as "%e" (this way no width adjustments are made)
 */
static char *
generate_format(double first, double incr, double last, int equalize, char pad)
{
        static char buf[256];
        char cc = '\0';
        int precision, width1, width2, places;

        if (equalize == 0)
                return default_format;

        /* figure out "last" value printed */
        if (first > last)
                last = first - incr * floor((first - last) / incr);
        else
                last = first + incr * floor((last - first) / incr);

        snprintf(buf, sizeof(buf), "%g", incr);
        if (strchr(buf, 'e'))
                cc = 'e';
        precision = decimal_places(buf);

        width1 = snprintf(buf, sizeof(buf), "%g", first);
        if (strchr(buf, 'e'))
                cc = 'e';
        if ((places = decimal_places(buf)))
                width1 -= (places + strlen(decimal_point));

        precision = MAXIMUM(places, precision);

        width2 = snprintf(buf, sizeof(buf), "%g", last);
        if (strchr(buf, 'e'))
                cc = 'e';
        if ((places = decimal_places(buf)))
                width2 -= (places + strlen(decimal_point));

        /* XXX if incr is floating point fix the precision */
        if (precision) {
                snprintf(buf, sizeof(buf), "%%%c%d.%d%c", pad,
                    MAXIMUM(width1, width2) + (int)strlen(decimal_point) +
                    precision, precision, (cc) ? cc : 'f');
        } else {
                snprintf(buf, sizeof(buf), "%%%c%d%c", pad,
                    MAXIMUM(width1, width2), (cc) ? cc : 'g');
        }

        return buf;
}

static __dead void
usage(int error)
{
        fprintf(stderr,
            "usage: %s [-w] [-f format] [-s string] [first [incr]] last\n",
            getprogname());
        exit(error);
}