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A set of utilities for classes of the java.lang and the java.util packages.
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/*
 * Copyright (C) 2011-2021 Objectos Software LTDA.
 *
 * This file is part of the ObjectosComuns project.
 *
 * ObjectosComuns is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * ObjectosComuns is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with ObjectosComuns.  If not, see .
 */
package br.com.objectos.lang;

import static br.com.objectos.lang.Lang.checkArgument;

public final class ByteUnit {

  public static final ByteUnit BINARY = new ByteUnit(
      1024L, "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"
  );

  public static final ByteUnit DECIMAL = new ByteUnit(
      1000L, "kB", "MB", "GB", "TB", "PB", "EB"
  );

  private static final char DECIMAL_SEPARATOR = '.';

  private final long kilo;

  private final long mega;

  private final long giga;

  private final long tera;

  private final long peta;

  private final long exa;

  private final String[] units;

  private ByteUnit(long kilo, String... units) {
    this.kilo = kilo;

    mega = kilo * kilo;

    giga = mega * kilo;

    tera = giga * kilo;

    peta = tera * kilo;

    exa = peta * kilo;

    this.units = units;
  }

  final String format(long bytes) {
    checkArgument(bytes >= 0, "bytes must be >= 0");

    StringBuilder result;
    result = new StringBuilder();

    if (bytes < kilo) {
      result.append(bytes);

      result.append(' ');

      result.append('B');

      return result.toString();
    }

    if (bytes < mega) {
      return format0(result, bytes, kilo, units[0]);
    }

    if (bytes < giga) {
      return format0(result, bytes, mega, units[1]);
    }

    if (bytes < tera) {
      return format0(result, bytes, giga, units[2]);
    }

    if (bytes < peta) {
      return format0(result, bytes, tera, units[3]);
    }

    if (bytes < exa) {
      return format0(result, bytes, peta, units[4]);
    }

    return format0(result, bytes, exa, units[5]);
  }

  private String format0(StringBuilder result, long bytes, long base, String unit) {
    double doubleValue;
    doubleValue = (double) bytes / base;

    int integerPart;
    integerPart = (int) doubleValue;

    result.append(integerPart);

    result.append(DECIMAL_SEPARATOR);

    double fractionalPart0;
    fractionalPart0 = doubleValue - (long) doubleValue;

    int fractionalPart;
    fractionalPart = (int) (fractionalPart0 * 10);

    result.append(fractionalPart);

    result.append(' ');

    result.append(unit);

    return result.toString();
  }

}