/*      $OpenBSD: number.c,v 1.20 2016/03/07 12:07:56 mestre Exp $      */

/*
 * Copyright (c) 1988, 1993, 1994
 *      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 <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define MAXNUM          65              /* Biggest number we handle. */
#define LINELEN         256

static const char       *const name1[] = {
        "",             "one",          "two",          "three",
        "four",         "five",         "six",          "seven",
        "eight",        "nine",         "ten",          "eleven",
        "twelve",       "thirteen",     "fourteen",     "fifteen",
        "sixteen",      "seventeen",    "eighteen",     "nineteen",
},
                *const name2[] = {
        "",             "ten",          "twenty",       "thirty",
        "forty",        "fifty",        "sixty",        "seventy",
        "eighty",       "ninety",
},
                *const name3[] = {
        "hundred",      "thousand",     "million",      "billion",
        "trillion",     "quadrillion",  "quintillion",  "sextillion",
        "septillion",   "octillion",    "nonillion",    "decillion",
        "undecillion",  "duodecillion", "tredecillion", "quattuordecillion",
        "quindecillion",                "sexdecillion", 
        "septendecillion",              "octodecillion",
        "novemdecillion",               "vigintillion",
};

void    convert(char *);
void    convertexp(char *);
int     number(const char *, int);
void    pfract(int);
int     unit(int, const char *);
__dead void     usage(void);

int lflag;

int
main(int argc, char *argv[])
{
        int ch, first;
        char line[LINELEN];

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

        lflag = 0;
        while ((ch = getopt(argc, argv, "hl")) != -1)
                switch (ch) {
                case 'l':
                        lflag = 1;
                        break;
                case 'h':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (*argv == NULL)
                for (first = 1;
                    fgets(line, sizeof(line), stdin) != NULL; first = 0) {
                        if (strchr(line, '\n') == NULL)
                                errx(1, "line too long.");
                        if (!first)
                                (void)printf("...\n");
                        convert(line);
                        if (lflag)
                                (void)printf("\n");
                }
        else
                for (first = 1; *argv != NULL; first = 0, ++argv) {
                        if (!first)
                                (void)printf("...\n");
                        convert(*argv);
                        if (lflag)
                                (void)printf("\n");
                }
        return 0;
}

void
convert(char *line)
{
        int flen, len, rval;
        char *p, *fraction;

        /* strip trailing and leading whitespace */
        len = strlen(line) - 1;
        while ((isblank((unsigned char)line[len])) || (line[len] == '\n'))
                line[len--] = '\0';
        while ((isblank((unsigned char)line[0])) || (line[0] == '\n'))
                line++;
        if (strchr(line, 'e') || strchr(line, 'E'))
                convertexp(line);
        else {
        fraction = NULL;
        for (p = line; *p != '\0' && *p != '\n'; ++p) {
                if (isblank((unsigned char)*p))
                        goto badnum;
                if (isdigit((unsigned char)*p))
                        continue;
                switch (*p) {
                case '.':
                        if (fraction != NULL)
                                goto badnum;
                        fraction = p + 1;
                        *p = '\0';
                        break;
                case '-':
                case '+':
                        if (p == line)
                                break;
                        /* FALLTHROUGH */
                default:
badnum:                 errx(1, "illegal number: %s", line);
                        break;
                }
        }
        *p = '\0';

        if ((len = strlen(line)) > MAXNUM ||
            ((fraction != NULL) && (flen = strlen(fraction)) > MAXNUM))
                errx(1, "number too long (max %d digits).", MAXNUM);

        if (*line == '-') {
                (void)printf("minus%s", lflag ? " " : "\n");
                ++line;
                --len;
        }
        if (*line == '+') {
                (void)printf("plus%s", lflag ? " " : "\n");
                ++line;
                --len;
        }

        rval = len > 0 ? unit(len, line) : 0;
        if (fraction != NULL && flen != 0)
                for (p = fraction; *p != '\0'; ++p)
                        if (*p != '0') {
                                if (rval)
                                        (void)printf("%sand%s",
                                            lflag ? " " : "",
                                            lflag ? " " : "\n");
                                if (unit(flen, fraction)) {
                                        if (lflag)
                                                (void)printf(" ");
                                        pfract(flen);
                                        rval = 1;
                                }
                                break;
                        }
        if (!rval)
                (void)printf("zero%s", lflag ? "" : ".\n");
        }
}

void
convertexp(char *line)
{
        char locline[LINELEN];
        char *part1, *part2, *part3, *part4;
        char tmp[2];
        int  i, j;

        (void)strlcpy(locline,line,LINELEN);
        part3 = locline;
        part2 = strsep(&part3, "eE");   /* part3 is the exponent */
        part4 = part3;
        (void)strsep(&part4, ".");      /* no decimal allowed in the exponent */        
        if (part4)
                errx(1, "illegal number: %s", line);
        part1 = strsep(&part2, ".");    /* we can have one in the mantissa */
        /* At this point everything should be null or a digit.  Check for
         * that before starting to convert.  Two characters may be + or -.
         */
        j = strlen(line);
        for (i = 0; i < j; i++)
                if ((!isdigit((unsigned char)locline[i])) && (locline[i]))
                        if (((locline[i] != '+') && (locline[i] != '-')) ||
                                ((i != 0) && (i != part3 - locline)))
                                errx(1, "illegal number: %s", line);
        convert(part1);
        printf("%s", lflag ? " " : "");
        if (part2 && part2[0]) {        /* do individual digits separately */
                (void)printf("point%s", lflag ? " " : "\n");
                j = strlen(part2); tmp[1] = '\0';
                for (i = 0 ; i < j; i++ ) {
                        tmp[0] = part2[i];
                        convert(tmp);
                        (void)printf("%s", lflag ? " " : "");
                }
        }
        (void)printf("times ten to the%s", lflag ? " " : "\n");
        if (part3 && part3[0])
                convert(part3);
        else
                (void)printf("zero%s", lflag ? " " : ".\n");
}

int
unit(int len, const char *p)
{
        int off, rval;

        rval = 0;
        if (len > 3) {
                if (len % 3) {
                        off = len % 3;
                        len -= off;
                        if (number(p, off)) {
                                rval = 1;
                                (void)printf(" %s%s",
                                    name3[len / 3], lflag ? " " : ".\n");
                        }
                        p += off;
                }
                for (; len > 3; p += 3) {
                        len -= 3;
                        if (number(p, 3)) {
                                rval = 1;
                                (void)printf(" %s%s",
                                    name3[len / 3], lflag ? " " : ".\n");
                        }
                }
        }
        if (number(p, len)) {
                if (!lflag)
                        (void)printf(".\n");
                rval = 1;
        }
        return (rval);
}

int
number(const char *p, int len)
{
        int val, rval;

        rval = 0;
        switch (len) {
        case 3:
                if (*p != '0') {
                        rval = 1;
                        (void)printf("%s hundred", name1[*p - '0']);
                }
                ++p;
                /* FALLTHROUGH */
        case 2:
                val = (p[1] - '0') + (p[0] - '0') * 10;
                if (val) {
                        if (rval)
                                (void)printf(" ");
                        if (val < 20)
                                (void)printf("%s", name1[val]);
                        else {
                                (void)printf("%s", name2[val / 10]);
                                if (val % 10)
                                        (void)printf("-%s", name1[val % 10]);
                        }
                        rval = 1;
                }
                break;
        case 1:
                if (*p != '0') {
                        rval = 1;
                        (void)printf("%s", name1[*p - '0']);
                }
        }
        return (rval);
}

void
pfract(int len)
{
        static const char *const pref[] = { "", "ten-", "hundred-" };

        switch(len) {
        case 1:
                (void)printf("tenths%s", lflag ? "" : ".\n");
                break;
        case 2:
                (void)printf("hundredths%s", lflag ? "" : ".\n");
                break;
        default:
                (void)printf("%s%sths%s", pref[len % 3], name3[len / 3],
                    lflag ? "" : ".\n");
                break;
        }
}

void
usage(void)
{
        (void)fprintf(stderr, "usage: %s [-l] [--] [# ...]\n", getprogname());
        exit(1);
}