1namespace domain
 2{
 3  using System;
 4
 5  public class Month : IComparable<Month>, IIncrementable<Month>
 6  {
 7    DateTime date;
 8    public static readonly Month Infinity = new Month(2099, 12);
 9
10    public Month(int year, int month)
11    {
12      date = new DateTime(year, month, 01);
13    }
14
15    public Month Plus(int months)
16    {
17      return ToMonth(date.AddMonths(months));
18    }
19
20    public bool IsBefore(Month other)
21    {
22      return this.CompareTo(other) < 0;
23    }
24
25    Month ToMonth(DateTime date)
26    {
27      return new Month(date.Year, date.Month);
28    }
29
30    static public Month Now()
31    {
32      var now = Clock.Now();
33      return new Month(now.Year, now.Month);
34    }
35
36    public int CompareTo(Month other)
37    {
38      return this.date.CompareTo(other.date);
39    }
40
41    public Month Next()
42    {
43      return Plus(1);
44    }
45
46    public bool Equals(Month other)
47    {
48      if (ReferenceEquals(null, other)) return false;
49      if (ReferenceEquals(this, other)) return true;
50      return other.date == date;
51    }
52
53    public override bool Equals(object obj)
54    {
55      if (ReferenceEquals(null, obj)) return false;
56      if (ReferenceEquals(this, obj)) return true;
57      if (obj.GetType() != typeof (Month)) return false;
58      return Equals((Month) obj);
59    }
60
61    public override int GetHashCode()
62    {
63      unchecked
64      {
65        return (date.Year*397) ^ date.Month;
66      }
67    }
68
69    public override string ToString()
70    {
71      return string.Format("{0} {1}", date.Year, date.Month);
72    }
73  }
74}