/*
 * 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.spark.network.util;

public enum ByteUnit {
  BYTE (1),
  KiB (1024L),
  MiB ((long) Math.pow(1024L, 2L)),
  GiB ((long) Math.pow(1024L, 3L)),
  TiB ((long) Math.pow(1024L, 4L)),
  PiB ((long) Math.pow(1024L, 5L));

  ByteUnit(long multiplier) {
    this.multiplier = multiplier;
  }

  // Interpret the provided number (d) with suffix (u) as this unit type.
  // E.g. KiB.interpret(1, MiB) interprets 1MiB as its KiB representation = 1024k
  public long convertFrom(long d, ByteUnit u) {
    return u.convertTo(d, this);
  }

  // Convert the provided number (d) interpreted as this unit type to unit type (u).
  public long convertTo(long d, ByteUnit u) {
    if (multiplier > u.multiplier) {
      long ratio = multiplier / u.multiplier;
      if (Long.MAX_VALUE / ratio < d) {
        throw new IllegalArgumentException("Conversion of " + d + " exceeds Long.MAX_VALUE in "
          + name() + ". Try a larger unit (e.g. MiB instead of KiB)");
      }
      return d * ratio;
    } else {
      // Perform operations in this order to avoid potential overflow
      // when computing d * multiplier
      return d / (u.multiplier / multiplier);
    }
  }

  public double toBytes(long d) {
    if (d < 0) {
      throw new IllegalArgumentException("Negative size value. Size must be positive: " + d);
    }
    return d * multiplier;
  }

  public long toKiB(long d) { return convertTo(d, KiB); }
  public long toMiB(long d) { return convertTo(d, MiB); }
  public long toGiB(long d) { return convertTo(d, GiB); }
  public long toTiB(long d) { return convertTo(d, TiB); }
  public long toPiB(long d) { return convertTo(d, PiB); }

  private final long multiplier;
}
