using System;
using System.Threading;

namespace AspClassic.Scripting;

public sealed class ScopeVariable : IScopeVariable, IWeakReferencable
{
	private object _value;

	private WeakReference _weakref;

	private static readonly object _novalue = new object();

	public bool HasValue => _value != _novalue;

	public WeakReference WeakReference
	{
		get
		{
			if (_weakref == null)
			{
				_weakref = new WeakReference(this);
			}
			return _weakref;
		}
	}

	internal ScopeVariable()
	{
		_value = _novalue;
	}

	public bool TryGetValue(out dynamic value)
	{
		value = _value;
		if ((object)value != _novalue)
		{
			return true;
		}
		value = null;
		return false;
	}

	public void SetValue(object value)
	{
		_value = value;
	}

	public bool DeleteValue()
	{
		return Interlocked.Exchange(ref _value, _novalue) != _novalue;
	}
}