/*
 * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * 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.
 * 3. Neither the name of The DragonFly Project 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 *
 * $DragonFly: src/usr.bin/seq/seq.c,v 1.1 2005/01/22 19:09:40 joerg Exp $
 */

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <math.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define ZERO    '0'
#define SPACE   ' '

#define MAX(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 */

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

/* Prototypes */

double  e_atof(const char *);

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

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

/*
 * 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, errflg = 0;
        int equalize = 0;
        double first = 1.0;
        double last = 0.0;
        double incr = 0.0;
        struct lconv *locale;
        char *fmt = NULL;
        const char *sep = "\n";
        const char *term = NULL;
        char pad = ZERO;

        /* 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(argc, argv, "f:hs:t:w")) != -1) {

                switch (c) {
                case 'f':       /* format (plan9) */
                        fmt = optarg;
                        equalize = 0;
                        break;
                case 's':       /* separator (GNU) */
                        sep = unescape(optarg);
                        break;
                case 't':       /* terminator (new) */
                        term = unescape(optarg);
                        break;
                case 'w':       /* equal width (plan9) */
                        if (!fmt)
                                if (equalize++)
                                        pad = SPACE;
                        break;
                case 'h':       /* help (GNU) */
                default:
                        errflg++;
                        break;
                }
        }

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

        if (errflg) {
                fprintf(stderr,
                    "usage: %s [-f format] [-s str] [-t str] [-w] [first [incr]] last\n",
                    getprogname());
                exit(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);
                fmt = unescape(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);

        if (incr > 0) {
                for (; first <= last; first += incr) {
                        printf(fmt, first);
                        fputs(sep, stdout);
                }
        } else {
                for (; first >= last; first += incr) {
                        printf(fmt, first);
                        fputs(sep, stdout);
                }
        }
        if (term != NULL)
                fputs(term, stdout);

        return(0);
}

/*
 * numeric - verify that string is numeric
 */
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 != '\0') {
                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)) {
                                        s++;
                                        continue;
                                }
                        }
                        break;
                }
                s++;
        }
        return(*s == '\0');
}

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

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

                                /* ok %% */
                                if (*fmt == '%') {
                                        fmt++;
                                        break;
                                }
                                /* valid conversions */
                                if (strchr("eEfgG", *fmt) &&
                                    conversions++ < 1) {
                                        fmt++;
                                        break;
                                }
                                /* flags, width and precsision */
                                if (isdigit((unsigned char)*fmt) ||
                                    strchr("+- 0#.", *fmt))
                                        continue;

                                /* oops! bad conversion format! */
                                return(0);
                        } while (*fmt != '\0');
                }
        }

        return(conversions <= 1);
}

/*
 * unescape - handle C escapes in a string
 */
char *
unescape(char *orig)
{
        char c, *cp, *new = orig;
        int i;

        for (cp = orig; (*orig = *cp) != '\0'; cp++, orig++) {
                if (*cp != '\\')
                        continue;

                switch (*++cp) {
                case 'a':       /* alert (bell) */
                        *orig = '\a';
                        continue;
                case 'b':       /* backspace */
                        *orig = '\b';
                        continue;
                case 'e':       /* escape */
                        *orig = '\e';
                        continue;
                case 'f':       /* formfeed */
                        *orig = '\f';
                        continue;
                case 'n':       /* newline */
                        *orig = '\n';
                        continue;
                case 'r':       /* carriage return */
                        *orig = '\r';
                        continue;
                case 't':       /* horizontal tab */
                        *orig = '\t';
                        continue;
                case 'v':       /* vertical tab */
                        *orig = '\v';
                        continue;
                case '\\':      /* backslash */
                        *orig = '\\';
                        continue;
                case '\'':      /* single quote */
                        *orig = '\'';
                        continue;
                case '\"':      /* double quote */
                        *orig = '"';
                        continue;
                case '0':
                case '1':
                case '2':
                case '3':       /* octal */
                case '4':
                case '5':
                case '6':
                case '7':       /* number */
                        for (i = 0, c = 0;
                             ISODIGIT((unsigned char)*cp) && i < 3;
                             i++, cp++) {
                                c <<= 3;
                                c |= (*cp - '0');
                        }
                        *orig = c;
                        continue;
                case 'x':       /* hexidecimal number */
                        cp++;   /* skip 'x' */
                        for (i = 0, c = 0;
                             isxdigit((unsigned char)*cp) && i < 2;
                             i++, cp++) {
                                c <<= 4;
                                if (isdigit((unsigned char)*cp))
                                        c |= (*cp - '0');
                                else
                                        c |= ((toupper((unsigned char)*cp) -
                                            'A') + 10);
                        }
                        *orig = c;
                        continue;
                default:
                        --cp;
                        break;
                }
        }

        return(new);
}

/*
 * 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
 */
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)
 */
int
decimal_places(const char *number)
{
        int places = 0;
        char *dp;

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

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

/*
 * generate_format - create a format string
 *
 * XXX to be bug for bug compatable with Plan9 and GNU return "%g"
 * when "%g" prints as "%e" (this way no width adjustments are made)
 */
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 = MAX(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));

        if (precision) {
                snprintf(buf, sizeof(buf), "%%%c%d.%d%c", pad,
                    MAX(width1, width2) + (int) strlen(decimal_point) +
                    precision, precision, (cc) ? cc : 'f');
        } else {
                snprintf(buf, sizeof(buf), "%%%c%d%c", pad,
                    MAX(width1, width2), (cc) ? cc : 'g');
        }

        return(buf);
}