gistfile1.scala

case class RichDate(val timestamp: Long) extends AnyVal with Ordered[RichDate] {
  //case class RichDate(val timestamp: Long) extends Ordered[RichDate] {
  // these are mutable, don't keep them around
  def value: Date = new java.util.Date(timestamp)

  def +(interval: Duration) = interval.addTo(this)
  def -(interval: Duration) = interval.subtractFrom(this)

  //Inverse of the above, d2 + (d1 - d2) == d1
  def -(that: RichDate) = AbsoluteDuration.fromMillisecs(timestamp - that.timestamp)

  override def compare(that: RichDate): Int =
    Ordering[Long].compare(timestamp, that.timestamp)

  /*
  //True of the other is a RichDate with equal value, or a Date equal to value
  override def equals(that: Any) =
    that match {
      case d: Date => d.getTime == timestamp
      case RichDate(ts) => ts == timestamp
      case _ => false
    }

*/
  /**
   * Use String.format to format the date, as opposed to toString with uses SimpleDateFormat
   */
  def format(pattern: String)(implicit tz: TimeZone): String = String.format(pattern, toCalendar(tz))

  /**
   * Make sure the hashCode is the same as Date for the (questionable) choice
   * to make them equal. this is the same as what java does (and only sane thing):
   * http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/util/Date.java#989
   */
  /*
  override def hashCode =
    (timestamp.toInt) ^ ((timestamp >> 32).toInt)
    */

  def toCalendar(implicit tz: TimeZone) = {
    val cal = Calendar.getInstance(tz)
    cal.setTime(value)
    cal
  }
  override def toString = value.toString

  /**
   * Use SimpleDateFormat to print the string
   */
  def toString(fmt: String)(implicit tz: TimeZone): String = {
    val cal = toCalendar(tz)
    val sdfmt = new SimpleDateFormat(fmt)
    sdfmt.setCalendar(cal)
    sdfmt.format(cal.getTime)
  }
}