/*      $NetBSD: humanize_number.c,v 1.19 2024/01/20 14:52:47 christos Exp $    */

/*
 * Copyright (c) 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
 * 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.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: humanize_number.c,v 1.19 2024/01/20 14:52:47 christos Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>

int
humanize_number(char *buf, size_t len, int64_t bytes,
    const char *suffix, int scale, int flags)
{
        const char *prefixes, *sep;
        int     b, i, r, s1, s2, sign;
        int64_t divisor, max, post = 1;
        size_t  baselen;
        int     maxscale;

        _DIAGASSERT(buf != NULL);
        _DIAGASSERT(scale >= 0);

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

        if (flags & HN_DIVISOR_1000) {
                /* SI for decimal multiplies */
                divisor = 1000;
                if (flags & HN_B)
                        prefixes = "B\0k\0M\0G\0T\0P\0E";
                else
                        prefixes = "\0\0k\0M\0G\0T\0P\0E";
        } else {
                /*
                 * binary multiplies
                 * XXX IEC 60027-2 recommends Ki, Mi, Gi...
                 */
                divisor = 1024;
                if (flags & HN_B)
                        prefixes = "B\0K\0M\0G\0T\0P\0E";
                else
                        prefixes = "\0\0K\0M\0G\0T\0P\0E";
        }

#define SCALE2PREFIX(scale)     (&prefixes[(scale) << 1])
        maxscale = 6;

        if (scale < 0 || (scale > maxscale &&
            (scale & (HN_AUTOSCALE | HN_GETSCALE)) == 0))
                return (-1);

        if (buf == NULL)
                return (-1);

        if (len > 0)
                buf[0] = '\0';

        if (bytes < 0) {
                sign = -1;
                baselen = 3;            /* sign, digit, prefix */
                if (-bytes < INT64_MAX / 100)
                        bytes *= -100;
                else {
                        bytes = -bytes;
                        post = 100;
                        baselen += 2;
                }
        } else {
                sign = 1;
                baselen = 2;            /* digit, prefix */
                if (bytes < INT64_MAX / 100)
                        bytes *= 100;
                else {
                        post = 100;
                        baselen += 2;
                }
        }
        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)) {
                /*
                 * 19 is number of digits in biggest possible int64_t
                 * If we don't do this, the calc of max just below can
                 * overflow, leading to absurd results.   If the buffer
                 * is big enough for the number, simply use it, no scaling.
                 */
                if (len - baselen > 19)
                        i = 0;
                else {
                        size_t j;
                        /* See if there are additional columns to be used. */
                        for (max = 100, j = len - baselen; j-- > 0;)
                                max *= 10;

                        /*
                         * Divide the number until it fits the avail buffer.
                         * If there will be an overflow by the rounding below,
                         * (the "-50") divide once more.
                         */
                        for (i = 0; bytes >= max - 50 && i < maxscale; i++)
                                bytes /= divisor;
                }
                if (scale & HN_GETSCALE) {
                        _DIAGASSERT(__type_fit(int, i));
                        return i;
                }
        } else {
                /* XXX
                 * we already know scale <= maxscale, so
                 * i < scale ==> i < maxscale
                 */
                for (i = 0; i < scale && i < maxscale; i++)
                        bytes /= divisor;
        }

        if (i == 0) {
                /*
                 * Cannot go the bytes *= post route, as
                 * that can cause overflow of bytes
                 *
                 * but if we already scaled up, undo that.
                 */
                if (post == 1)
                        bytes /= 100;

                r = snprintf(buf, len, "%" PRId64 "%s%s%s",
                    sign * bytes, sep, SCALE2PREFIX(0), suffix);
        } else {
                /*
                 * Here this is safe, as if i > 0, we have already
                 * divided bytes by at least 1000, post <= 100, so ...
                 */
                bytes *= post;

                /* If a value <= 9.9 after rounding and ... */
                if (bytes < 995 && i > 0 && flags & HN_DECIMAL) {
                        /* baselen + \0 + .N */
                        if (len < baselen + 1 + 1 +
                            strlen(localeconv()->decimal_point))
                                return (-1);
                        b = ((int)bytes + 5) / 10;
                        s1 = b / 10;
                        s2 = b % 10;
                        r = snprintf(buf, len, "%d%s%d%s%s%s",
                            sign * s1, localeconv()->decimal_point, s2,
                            sep, SCALE2PREFIX(i), suffix);
                } else
                        r = snprintf(buf, len, "%" PRId64 "%s%s%s",
                            sign * ((bytes + 50) / 100),
                            sep, SCALE2PREFIX(i), suffix);
        }

        if ((size_t)r > len)
                r = -1;

        return (r);
}