using System;
using System.Runtime.Serialization;

[Serializable]
public class Date{
  private ushort year;
  private byte month, day;

  [NonSerialized()]
  private DayOfWeek nameOfDay;

  public Date(int year, int month, int day){
    this.year =  (ushort)year; 
    this.month = (byte)month; 
    this.day =   (byte)day;
    this.nameOfDay = (new DateTime(year, month, day)).DayOfWeek;
  }

  public Date(Date d){
    this.year = d.year; this.month = d.month; 
    this.day = d.day; this.nameOfDay = d.nameOfDay;
  }

  [OnDeserialized()]
  internal void FixDateAfterDeserializing(
                                   StreamingContext context){
    nameOfDay = (new DateTime(year, month, day)).DayOfWeek;    
  }

  public int Year{get{return year;}}
  public int Month{get{return month;}}
  public int Day{get{return day;}}

  // return this minus other, as of usual birthday calculations.
  public int YearDiff(Date other){
    if (this.Equals(other))
       return 0;
    else if ((new Date(other.year, this.month, this.day)).IsBefore(other))
      return this.year - other.year - 1; 
    else
      return this.year - other.year;
  }

  public override bool Equals(Object obj){
     if (obj == null)
       return false;
     else if (this.GetType() != obj.GetType())
       return false;
     else if (ReferenceEquals(this, obj))
       return true;
     else if (this.year == ((Date)obj).year &&
              this.month == ((Date)obj).month &&
              this.day == ((Date)obj).day)
       return true;
     else return false;
   }

  // Is this date less than other date
  public bool IsBefore(Date other){
    return 
      this.year < other.year ||
      this.year == other.year && this.month < other.month ||
      this.year == other.year && this.month == other.month && this.day < other.day;
  }


  public static Date Today{
    get{
      DateTime now = DateTime.Now;
      return new Date(now.Year, now.Month, now.Day);}
  }

  public override string ToString(){
    return string.Format("{0} {1}.{2}.{3}", nameOfDay, day, month, year);
  }
}