#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, 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, FMT_STRING("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, FMT_STRING("buffer size {} insufficient for minimum size {}"), len, baselen);
  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;
    return fmt::format(FMT_STRING("{}{}{}{}{}{}"), sign * s1, localeconv()->decimal_point, s2, sep, SCALE2PREFIX(i), suffix);
  } else
    return fmt::format(FMT_STRING("{}{}{}{}"), sign * (quotient + (remainder + divisor / 2) / divisor), sep,
                       SCALE2PREFIX(i), suffix);
}

} // namespace hecl