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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rapiddweller.common.file;

import com.rapiddweller.common.BinaryScale;

import java.text.DecimalFormat;

/**
 * Formats a number in a human-friendly manner, e.g. a file size in megabytes.
 * Created: 06.03.2011 15:12:55
 *
 * @author Volker Bergmann
 * @since 0.5.8
 */
public class BinaryScaleFormatter {

  private final BinaryScale scale;
  private final DecimalFormat numberFormat;
  private final String unit;

  /**
   * Instantiates a new Binary scale formatter.
   *
   * @param scale the scale
   * @param unit  the unit
   */
  public BinaryScaleFormatter(BinaryScale scale, String unit) {
    this.scale = scale;
    this.unit = unit;
    this.numberFormat = new DecimalFormat();
    setGroupingUsed(true);
  }

  /**
   * Sets grouping used.
   *
   * @param groupingUsed the grouping used
   */
  public void setGroupingUsed(boolean groupingUsed) {
    this.numberFormat.setGroupingUsed(groupingUsed);
  }

  /**
   * Format string.
   *
   * @param number the number
   * @return the string
   */
  public String format(long number) {
    if (scale != null) {
      return applyScale(scale, number);
    } else {
      return applyAutoScale(number);
    }
  }

  private String applyScale(BinaryScale scale, long number) {
    return numberFormat.format(Math.floor((number + scale.getFactor() - 1) / scale.getFactor())) + " " + scale.getDesignator() + unit;
  }

  private String applyAutoScale(long number) {
    if (number >= 10 * BinaryScale.TERA.getFactor()) {
      return applyScale(BinaryScale.TERA, number);
    } else if (number >= 10 * BinaryScale.GIGA.getFactor()) {
      return applyScale(BinaryScale.GIGA, number);
    } else if (number >= 10 * BinaryScale.MEGA.getFactor()) {
      return applyScale(BinaryScale.MEGA, number);
    } else if (number >= 10 * BinaryScale.KILO.getFactor()) {
      return applyScale(BinaryScale.KILO, number);
    } else {
      return applyScale(BinaryScale.NONE, number);
    }
  }

}