using System;
using System.Collections.Generic;

namespace BITKit
{
	/// <summary>
	/// 双缓冲区
	/// </summary>
	/// <typeparam name="T"></typeparam>
	public interface IDoubleBuffer<T>
	{
		bool CanRelease { get; }
		T Current { get; }
		void Release(T newValue);
		event Action<T> OnRelease;
		bool TryGetRelease(out T result);
	}
	/// <summary>
	/// <see cref="IDoubleBuffer{T}"/>
	/// </summary>
	/// <typeparam name="T"></typeparam>
	public class DoubleBuffer<T> : IDoubleBuffer<T>
	{
		public bool CanRelease => _release.Allow;

		public T Current
		{
			get;
			// ReSharper disable once MemberCanBePrivate.Global
			protected set;
		}

		public void Release(T newValue)
		{
			Current = newValue;
			OnRelease?.Invoke(newValue);
			_release.SetValueThenAllow(newValue);
		}

		public void Clear()
		{
			_release.Clear();
		}

		public event Action<T> OnRelease;
		private readonly Optional<T> _release=new();

		public bool TryGetRelease(out T result)
		{
			result = _release.Value;
			if (!_release.Allow) return _release.Allow;
			_release.Clear();
			return true;
		}
	}
}