/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Portions Copyright 2007 Sun Microsystems, Inc.
 */
package org.opends.server.admin;



import java.util.HashMap;
import java.util.Map;



/**
 * This enumeration defines various duration units.
 */
public enum DurationUnit {

  /**
   * A millisecond unit.
   */
  MILLI_SECONDS(1L, "ms", "milliseconds"),

  /**
   * A second unit.
   */
  SECONDS(1000L, "s", "seconds"),

  /**
   * A minute unit.
   */
  MINUTES((long) 60 * 1000, "m", "minutes"),

  /**
   * An hour unit.
   */
  HOURS((long) 60 * 60 * 1000, "h", "hours"),

  /**
   * A day unit.
   */
  DAYS((long) 24 * 60 * 60 * 1000, "d", "days"),

  /**
   * A week unit.
   */
  WEEKS((long) 7 * 24 * 60 * 60 * 1000, "w", "weeks");

  // A lookup table for resolving a unit from its name.
  private static final Map<String, DurationUnit> nameToUnit;
  static {
    nameToUnit = new HashMap<String, DurationUnit>();

    for (DurationUnit unit : DurationUnit.values()) {
      nameToUnit.put(unit.shortName, unit);
      nameToUnit.put(unit.longName, unit);
    }
  }

  // The size of the unit in milli-seconds.
  private final long sz;

  // The abbreviation of the unit.
  private final String shortName;

  // The long name of the unit.
  private final String longName;



  // Private constructor.
  private DurationUnit(long sz, String shortName, String longName) {
    this.sz = sz;
    this.shortName = shortName;
    this.longName = longName;
  }



  /**
   * Get the unit corresponding to the provided unit name.
   *
   * @param s
   *          The name of the unit. Can be the abbreviated or long name and can
   *          contain white space and mixed case characters.
   * @return Returns the unit corresponding to the provided unit name.
   * @throws IllegalArgumentException
   *           If the provided name did not correspond to a known duration unit.
   */
  public static DurationUnit getUnit(String s) throws IllegalArgumentException {
    DurationUnit unit = nameToUnit.get(s.trim().toLowerCase());
    if (unit == null) {
      throw new IllegalArgumentException("Illegal duration unit \"" + s + "\"");
    }
    return unit;
  }



  /**
   * Get the abbreviated name of this unit.
   *
   * @return Returns the abbreviated name of this unit.
   */
  public String getShortName() {
    return shortName;
  }



  /**
   * Get the long name of this unit.
   *
   * @return Returns the long name of this unit.
   */
  public String getLongName() {
    return longName;
  }



  /**
   * Get the number of milli-seconds that this unit represents.
   *
   * @return Returns the number of milli-seconds that this unit represents.
   */
  public long getDuration() {
    return sz;
  }



  /**
   * Converts the specified duration in this unit to milli-seconds.
   *
   * @param duration
   *          The duration.
   * @return Returns the number of milli-seconds that the duration represents.
   */
  public long getDuration(double duration) {
    return (long) (sz * duration);
  }



  /**
   * Converts a duration in this unit to the specified unit.
   *
   * @param duration
   *          The duration.
   * @param unit
   *          The required unit.
   * @return Returns a value representing the duration in the specified unit.
   */
  public double getDuration(double duration, DurationUnit unit) {
    return (sz * duration) / unit.sz;
  }



  /**
   * Get the best-fit unit for the specified duration in this unit. For example,
   * if this unit is minutes and the duration 120 is provided, then the best fit
   * unit is hours: 2h. Similarly, if the duration is 0.5, then the best fit
   * unit will by seconds: 30s.
   *
   * @param duration
   *          The duration.
   * @return Returns the best-fit unit for the specified duration in this unit.
   */
  public DurationUnit getBestFitUnit(double duration) {
    for (DurationUnit unit :
            new DurationUnit[]{WEEKS, DAYS, HOURS, MINUTES, SECONDS}) {
      double v = getDuration(duration, unit);
      if (Double.isInfinite(v) || Double.isNaN(v) || v == 0) {
        return this;
      }
      if (v >= 1 && Math.floor(v) == Math.ceil(v)) {
        return unit;
      }
    }
    return MILLI_SECONDS;
  }



  /**
   * {@inheritDoc}
   * <p>
   * This implementation returns the abbreviated name of this duration unit.
   */
  @Override
  public String toString() {
    return shortName;
  }
}