namespace Kit.Helpers
{
    /// <summary>Сервис для синхронизации потоков по ключу на основе словаря в памяти приложения</summary>
    /// <typeparam name="TKey">ключ синхронизации</typeparam>
    public class MemoryLockDictionaryService<TKey>: ILockDictionaryService<TKey> where TKey : notnull
    {
        private object _lockObjectLock;
        private IDictionary<TKey, object> _lockObjects;

        public MemoryLockDictionaryService()
        {
            _lockObjectLock = new object();
            _lockObjects = new Dictionary<TKey, object>();
        }

        private object GetLockObject(TKey lockKey)
        {
            lock (_lockObjectLock)
            {
                if (_lockObjects.ContainsKey(lockKey) == false) _lockObjects.Add(lockKey, new object());
                return _lockObjects[lockKey];
            }
        }

        private void RemoveLockObject(TKey lockKey)
        {
            // дожидаемся освобождения объекта
            lock (this.GetLockObject(lockKey)) { }

            // удаляем объект блокировки из очереди
            lock (_lockObjectLock) { _lockObjects.Remove(lockKey); }
        }

        public void ExecuteOnLock(TKey lockKey, Action action)
        {
            try
            {
                lock (GetLockObject(lockKey))
                {
                    action();
                }
                RemoveLockObject(lockKey);
            }
            catch
            {
                throw;
            }
            finally
            {
            }
        }

        public TResult ExecuteOnLock<TResult>(TKey lockKey, Func<TResult> action)
        {
            try
            {
                lock (GetLockObject(lockKey))
                {
                    return action();
                }
            }
            catch
            {
                throw;
            }
            finally
            {
                RemoveLockObject(lockKey);
            }
        }
    }
}