using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;

namespace DerivedEquals
{
  internal sealed class NamedAsciiEncoding : ASCIIEncoding
  {
    public readonly string Name;

    public NamedAsciiEncoding(string name)
    {
      Name = name;
    }

    public override bool Equals(object obj)
    {
      var other = obj as NamedAsciiEncoding;
      if (other == null)
        return false;
      if (!base.Equals(other))
        return false;
      return Name == other.Name;
    }

    public override int GetHashCode()
    {
      int hash = base.GetHashCode();
      if (Name != null)
        hash ^= Name.GetHashCode();
      return hash;
    }
  }

  internal sealed class AnnotatedCultureInfo : CultureInfo
  {
    public readonly string Annotation;

    public AnnotatedCultureInfo(string cultureName, string annotation)
      : base(cultureName)
    {
      Annotation = annotation;
    }

    public override bool Equals(object obj)
    {
      var other = obj as AnnotatedCultureInfo;
      if (other == null)
        return false;
      if (!base.Equals(other))
        return false;
      return Annotation == other.Annotation;
    }

    public override int GetHashCode()
    {
      int hash = base.GetHashCode();
      if (Annotation != null)
        hash ^= Annotation.GetHashCode();
      return hash;
    }
  }

  internal sealed class ColoredUri : Uri
  {
    public readonly string Color;

    public ColoredUri(string uriString, string color)
      : base(uriString)
    {
      Color = color;
    }

    public override bool Equals(object obj)
    {
      var other = obj as ColoredUri;
      if (other == null)
        return false;
      if (!base.Equals(other))
        return false;
      return Color == other.Color;
    }

    public override int GetHashCode()
    {
      int hash = base.GetHashCode();
      if (Color != null)
        hash ^= Color.GetHashCode();
      return hash;
    }
  }

  internal static class Program
  {
    private static void Main()
    {
      var baseAE = new ASCIIEncoding();
      var johnDoeAE = new NamedAsciiEncoding("John Doe");
      Console.WriteLine(Object.Equals(baseAE, johnDoeAE)); // True
      Console.WriteLine(Object.Equals(johnDoeAE, baseAE)); // False
      Console.WriteLine(EqualityComparer<ASCIIEncoding>.Default.Equals(baseAE, johnDoeAE)); // True
      Console.WriteLine(EqualityComparer<ASCIIEncoding>.Default.Equals(johnDoeAE, baseAE)); // False


      var baseCI = new CultureInfo("da-DK");
      var annCI = new AnnotatedCultureInfo("da-DK", "Remember these words!");
      Console.WriteLine(Object.Equals(baseCI, annCI)); // True
      Console.WriteLine(Object.Equals(annCI, baseCI)); // False
      Console.WriteLine(EqualityComparer<CultureInfo>.Default.Equals(baseCI, annCI)); // True
      Console.WriteLine(EqualityComparer<CultureInfo>.Default.Equals(annCI, baseCI)); // False


      var baseUri = new Uri("http://www.microsoft.com/");
      var greenUri = new ColoredUri("http://www.microsoft.com/", "green");
      Console.WriteLine(Object.Equals(baseUri, greenUri)); // True
      Console.WriteLine(Object.Equals(greenUri, baseUri)); // False
      Console.WriteLine(EqualityComparer<Uri>.Default.Equals(baseUri, greenUri)); // True
      Console.WriteLine(EqualityComparer<Uri>.Default.Equals(greenUri, baseUri)); // False
    }
  }
}