using System;
using System.Collections.Generic;

namespace ScreenConnect;

public static class KeyComparer
{
	private class CustomKeyEqualityComparer<T, TKey>(Func<T, TKey> keyExtractor, IEqualityComparer<TKey> keyEqualityComparer) : IEqualityComparer<T> where TKey : notnull
	{
		public bool Equals(T? x, T? y)
		{
			return keyEqualityComparer.Equals(keyExtractor(x), keyExtractor(y));
		}

		public int GetHashCode(T obj)
		{
			return keyExtractor(obj).GetHashCode();
		}
	}

	private class EquatableKeyEqualityComparer<T, TKey>(Func<T, TKey> keyExtractor) : IEqualityComparer<T> where TKey : IEquatable<TKey>
	{
		public bool Equals(T? x, T? y)
		{
			return keyExtractor(x).Equals(keyExtractor(y));
		}

		public int GetHashCode(T obj)
		{
			return keyExtractor(obj).GetHashCode();
		}
	}

	private class CustomKeyComparer<T, TKey>(Func<T, TKey> keyExtractor, IComparer<TKey> keyComparer) : IComparer<T> where TKey : notnull
	{
		public int Compare(T? x, T? y)
		{
			return keyComparer.Compare(keyExtractor(x), keyExtractor(y));
		}
	}

	private class ComparableKeyComparer<T, TKey>(Func<T, TKey> keyExtractor) : IComparer<T> where TKey : IComparable<TKey>
	{
		public int Compare(T? x, T? y)
		{
			return keyExtractor(x).CompareTo(keyExtractor(y));
		}
	}

	public static IEqualityComparer<T> CreateEqualityComparer<T, TKey>(Func<T, TKey> keyExtractor) where TKey : IEquatable<TKey>
	{
		return new EquatableKeyEqualityComparer<T, TKey>(keyExtractor);
	}

	public static IEqualityComparer<T> CreateEqualityComparer<T, TKey>(Func<T, TKey> keyExtractor, IEqualityComparer<TKey> keyEqualityComparer) where TKey : notnull
	{
		return new CustomKeyEqualityComparer<T, TKey>(keyExtractor, keyEqualityComparer);
	}

	public static IComparer<T> CreateComparer<T, TKey>(Func<T, TKey> keyExtractor) where TKey : IComparable<TKey>
	{
		return new ComparableKeyComparer<T, TKey>(keyExtractor);
	}

	public static IComparer<T> CreateComparer<T, TKey>(Func<T, TKey> keyExtractor, IComparer<TKey> keyComparer) where TKey : notnull
	{
		return new CustomKeyComparer<T, TKey>(keyExtractor, keyComparer);
	}
}