// Licensed to the .NET Foundation under one or more agreements.

// The .NET Foundation licenses this file to you under the MIT license.

// See the LICENSE file in the project root for more information.

using System.Collections.Generic;

using System.Linq;

namespace System

{

// A wrapped integer that invokes a custom delegate every time IEquatable<TInt>.Equals() is invoked.

internal struct TInt : IEquatable<TInt>, IComparable<TInt>

{

public TInt(int value)

: this(value, (Action<int, int>)null)

{

// This constructor does not report comparisons but is still useful for catching uses of the boxing Equals().

}

public TInt(int value, Action<int, int> onCompare)

{

Value = value;

_onCompare = onCompare;

}

public TInt(int value, TIntLog log)

{

Value = value;

_onCompare = (x, y) => log.Add(x, y);

}

public bool Equals(TInt other)

{

_onCompare?.Invoke(Value, other.Value);

return Value == other.Value;

}

public int CompareTo(TInt other)

{

_onCompare?.Invoke(Value, other.Value);

return Value.CompareTo(other.Value);

}

#pragma warning disable 0809 // Obsolete member 'TInt.Equals(object)' overrides non-obsolete member 'object.Equals(object)'

[Obsolete("Don't call this. Call IEquatable<T>.Equals(T)")]

public override bool Equals(object obj)

{

throw new NotSupportedException("Unexpected use of boxing Equals().");

}

#pragma warning restore 0809

public override int GetHashCode() => Value.GetHashCode();

public override string ToString()

{

return Value.ToString();

}

public int Value { get; }

private Action<int, int> _onCompare;

}

internal sealed class TIntLog

{

public void Add(int x, int y) => _log.Add(Tuple.Create(x, y));

public int Count => _log.Count;

public int CountCompares(int x, int y) => _log.Where(t => (t.Item1 == x && t.Item2 == y) || (t.Item1 == y && t.Item2 == x)).Count();

private List<Tuple<int, int>> _log = new List<Tuple<int, int>>();

}

}