/*      $NetBSD: humanize_number.c,v 1.14 2008/04/28 20:22:59 martin Exp $      */

/*
 * Copyright (c) 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
 * Copyright 2013 John-Mark Gurney <jmg@FreeBSD.org>
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center, by Luke Mewburn and by Tomas Svensson.
 *
 * 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.
 *
 * $FreeBSD: head/lib/libutil/humanize_number.c 256130 2013-10-07 22:22:57Z jmg $
 */

#include <sys/types.h>
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <libutil.h>

static const int maxscale = 7;

int
humanize_number(char *buf, size_t len, int64_t quotient,
    const char *suffix, int scale, int flags)
{
        const char *prefixes, *sep;
        int     i, r, remainder, s1, s2, sign;
        int     divisordeccut;
        int64_t divisor, max;
        size_t  baselen;

        /* validate args */
        if (buf == NULL)
                return (-1);
        if (scale < 0)
                return (-1);
        else if (scale >= maxscale &&
            ((scale & ~(HN_AUTOSCALE|HN_GETSCALE)) != 0))
                return (-1);
        if ((flags & HN_DIVISOR_1000) && (flags & HN_IEC_PREFIXES))
                return (-1);

        /* Since so many callers don't check -1, NUL terminate the buffer */
        if (len > 0)
                buf[0] = '\0';

        if (suffix == NULL)
                suffix = "";

        /* setup parameters */
        remainder = 0;

        if (flags & HN_IEC_PREFIXES) {
                baselen = 2;
                /*
                 * Use the prefixes for power of two recommended by
                 * the International Electrotechnical Commission
                 * (IEC) in IEC 80000-3 (i.e. Ki, Mi, Gi...).
                 *
                 * HN_IEC_PREFIXES implies a divisor of 1024 here
                 * (use of HN_DIVISOR_1000 would have triggered
                 * an assertion earlier).
                 */
                divisor = 1024;
                divisordeccut = 973;    /* ceil(.95 * 1024) */
                if (flags & HN_B)
                        prefixes = "B\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
                else
                        prefixes = "\0\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
        } else {
                baselen = 1;
        if (flags & HN_DIVISOR_1000) {
                divisor = 1000;
                        divisordeccut = 950;
                if (flags & HN_B)
                                prefixes = "B\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
                else
                                prefixes = "\0\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
        } else {
                divisor = 1024;
                        divisordeccut = 973;    /* ceil(.95 * 1024) */
                if (flags & HN_B)
                                prefixes = "B\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
                else
                                prefixes = "\0\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
                }
        }

#define SCALE2PREFIX(scale)     (&prefixes[(scale) * 3])

        if (quotient < 0) {
                sign = -1;
                quotient = -quotient;
                baselen += 2;           /* sign, digit */
        } else {
                sign = 1;
                baselen += 1;           /* digit */
        }
        if (flags & HN_NOSPACE)
                sep = "";
        else {
                sep = " ";
                baselen++;
        }
        baselen += strlen(suffix);

        /* Check if enough room for `x y' + suffix + `\0' */
        if (len < baselen + 1)
                return (-1);

        if (scale & (HN_AUTOSCALE | HN_GETSCALE)) {
                /* See if there is additional columns can be used. */
                for (max = 1, i = len - baselen; i-- > 0;)
                        max *= 10;

                /*
                 * Divide the number until it fits the given column.
                 * If there will be an overflow by the rounding below,
                 * divide once more.
                 */
                for (i = 0;
                    (quotient >= max || (quotient == max - 1 &&
                    remainder >= divisordeccut)) && i < maxscale; i++) {
                        remainder = quotient % divisor;
                        quotient /= divisor;
                }

                if (scale & HN_GETSCALE)
                        return (i);
        } else {
                for (i = 0; i < scale && i < maxscale; i++) {
                        remainder = quotient % divisor;
                        quotient /= divisor;
                }
        }

        /*
         * Generate base output
         */
        r = snprintf(buf, len, "%" PRId64 "%s%s%s",
            sign * (quotient + (remainder + divisor / 2) / divisor),
            sep, SCALE2PREFIX(i), suffix);

        if ((flags & HN_FRACTIONAL) && (u_int)r + 3 <= len && i) {
                /*
                 * If FRACTIONAL is specified output up to two fractional
                 * digits, unless the value was not divided out.
                 */
                int64_t frac;
                int n;

                n = (int)len - r - 2;
                frac = 1;
                if (n > 2)      /* max 2 fractional digits */
                        n = 2;

                while (n) {
                        frac = frac * 10;
                        --n;
                }
                s1 = (int)quotient + ((remainder * frac + divisor / 2) /
                    divisor / frac);
                s2 = ((remainder * frac + divisor / 2) / divisor) % frac;
                r = snprintf(buf, len, "%d%s%d%s%s%s",
                    sign * s1, localeconv()->decimal_point, s2,
                    sep, SCALE2PREFIX(i), suffix);
        } else if ((flags & HN_DECIMAL) && (u_int)r + 3 <= len &&
                (((quotient == 9 && remainder < divisordeccut) ||
                    quotient < 9) && i > 0)) {
                /*
                 * If DECIMAL is specified and the value is <= 9.9 after
                 * rounding, and it fits, add one fractional digit.
                 */
                s1 = (int)quotient + ((remainder * 10 + divisor / 2) /
                    divisor / 10);
                s2 = ((remainder * 10 + divisor / 2) / divisor) % 10;
                r = snprintf(buf, len, "%d%s%d%s%s%s",
                    sign * s1, localeconv()->decimal_point, s2,
                    sep, SCALE2PREFIX(i), suffix);
        }
        return (r);
}