using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

// A spot for immutable helpers

namespace imm
{
	public record class Versioned<T>
		where T: Versioned<T>
	{
		public uint   Version { get; protected set; } = 0;
		public string Reason  { get; protected set; } = "";

		public T Process(Func<T, T> fn, string reason = "")
		{
			var newT = fn((T)this);

			return newT with
			{
				Version = newT.Version + 1,
				Reason = reason,
			};
		}
	}

	public record class Recorded<T> : Versioned<T>
		where T : Recorded<T>
	{
		public T? Old { get; private set; }
		public string Expression { get; private set; } = "";
		public string MemberName { get; private set; } = "";
		public string FilePath { get; private set; } = "";
		public int LineNumber { get; private set; } = -1;

		public T Record(string reason = "",
														[CallerMemberName] string memberName = "",
														[CallerFilePath] string filePath = "",
														[CallerLineNumber] int lineNumber = 0)
		{
			var orig = (T)this;

			var newT = base.Process((old) => old with 
			{
				Old = orig,
				MemberName = memberName,
				FilePath = filePath,
				LineNumber = lineNumber,
			}, reason);

			return newT;
		}


		public T Process(Func<T, T> fn, string reason = "",
														[CallerMemberName] string memberName = "",
														[CallerFilePath] string filePath = "",
														[CallerLineNumber] int lineNumber = 0,
														[CallerArgumentExpression("fn")]
														string expression = default)
		{
			var orig = (T)this;

			return (T)this with
			{
				//Do the Versioned code here
				Version = orig.Version + 1,

				//Recorded
				Old = orig,
				Expression = expression,
				MemberName = memberName,
				FilePath = filePath,
				LineNumber = lineNumber,
			};
		}
	}


	public static class Util
	{




	}

}