using System.Threading;
 
namespace GTAMapper.Extensions.Threading
{
    /// <summary>
    /// Thread safe enter once into a code block:
    /// the first call to CheckAndSetFirstCall returns always true,
    /// all subsequent call return false.
    /// </summary>
    public class ThreadSafeBool
    {
        private static int NOTCALLED = 0,
                           CALLED = 1;
 
        private int _state = NOTCALLED;
 
        /// <summary>Explicit call to check and set if this is the first call</summary>
        public bool Value
        {
            get
            {
                return Interlocked.Exchange(ref _state, CALLED) == NOTCALLED;
            }
        }
 
        /// <summary>usually init by false</summary>
        public static implicit operator ThreadSafeBool(bool called)
        {
            return new ThreadSafeBool() { _state = called ? CALLED : NOTCALLED };
        }
 
        public static implicit operator bool(ThreadSafeBool cast)
        {
            if (cast == null)
                return false;
 
            return cast.Value;
        }
    }
}