/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.iotdb.tsfile.utils;

import java.io.File;

import org.apache.iotdb.tsfile.fileSystem.FSFactoryProducer;

/**
 * FileUtils is just used for return file attribute like file size, and contains
 * some measurement conversion among B, KB, MB etc.
 */
public class FileUtils {

  public static double getLocalFileByte(String filePath, Unit unit) {
    File f = FSFactoryProducer.getFSFactory().getFile(filePath);
    return getLocalFileByte(f, unit);
  }

  public static double getLocalFileByte(File file, Unit unit) {
    return format(transformUnit(file.length(), unit), 2);
  }

  /**
   * transform the byte value number to another unit.
   *
   * @param value - a number represented Byte which to be transformed
   * @param unit  - the target unit to be transformed
   * @return - value number in unit of given parameter
   */
  public static double transformUnit(double value, Unit unit) {
    return value / Math.pow(1024, unit.ordinal());
  }

  /**
   * transform the value number from other unit to Byte unit.
   *
   * @param value - a number to be transformed
   * @param unit  - the source unit to be transformed, maybe in unit of KB, MB, GB
   * @return - value number in unit of Byte
   */
  public static double transformUnitToByte(double value, Unit unit) {
    return value * Math.pow(1024, unit.ordinal());
  }

  /**
   * reserves some decimal for given double value
   *
   * @param num   - given double value
   * @param round - reserved decimal number
   * @return - double value in given decimal number
   */
  public static double format(double num, int round) {
    long a = (long) (num * Math.pow(10, round));
    return ((double) a) / Math.pow(10, round);
  }

  public static enum Unit {
    B, KB, MB, GB, TB, PB, EB
  }
}
