#include "hecl/hecl.hpp"
#include "logvisor/logvisor.hpp"

/*
 * 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.
 */

namespace hecl
{
static logvisor::Module Log("hecl::HumanizeNumber");

static const int maxscale = 7;

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

    /* validate args */
    if (suffix == nullptr)
        suffix = "";
    if ((flags & HNFlags::Divisor1000) != HNFlags::None && (flags & HNFlags::IECPrefixes) != HNFlags::None)
        Log.report(logvisor::Fatal, "invalid flags combo");

    /* setup parameters */
    remainder = 0;

    if ((flags & HNFlags::IECPrefixes) != HNFlags::None) {
        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 & HNFlags::B) != HNFlags::None)
            prefixes = "B\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
        else
            prefixes = "\0\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
    } else {
        baselen = 1;
        if ((flags & HNFlags::Divisor1000) != HNFlags::None) {
            divisor = 1000;
            divisordeccut = 950;
            if ((flags & HNFlags::B) != HNFlags::None)
                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 & HNFlags::B) != HNFlags::None)
                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 & HNFlags::NoSpace) != HNFlags::None)
        sep = "";
    else {
        sep = " ";
        baselen++;
    }
    baselen += strlen(suffix);

    /* Check if enough room for `x y' + suffix */
    if (len < baselen)
        Log.report(logvisor::Fatal,
                   "buffer size %" PRISize "insufficient for minimum size %" PRISize,
                   len, baselen);
    std::string ret(len, '\0');
    len += 1;

    if ((scale & int(HNScale::AutoScale)) != 0) {
        /* 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;
        }
    } else {
        for (i = 0; i < scale && i < maxscale; i++) {
            remainder = quotient % divisor;
            quotient /= divisor;
        }
    }

    /* If a value <= 9.9 after rounding and ... */
    /*
     * XXX - should we make sure there is enough space for the decimal
     * place and if not, don't do HN_DECIMAL?
     */
    if (((quotient == 9 && remainder < divisordeccut) || quotient < 9) &&
            i > 0 && (flags & HNFlags::Decimal) != HNFlags::None) {
        s1 = (int)quotient + ((remainder * 10 + divisor / 2) /
                              divisor / 10);
        s2 = ((remainder * 10 + divisor / 2) / divisor) % 10;
        r = snprintf(&ret[0], len, "%d%s%d%s%s%s",
                     sign * s1, localeconv()->decimal_point, s2,
                     sep, SCALE2PREFIX(i), suffix);
    } else
        r = snprintf(&ret[0], len, "%" PRId64 "%s%s%s",
                     sign * (quotient + (remainder + divisor / 2) / divisor),
                     sep, SCALE2PREFIX(i), suffix);

    return ret;
}

}