using System.Collections.Concurrent;
using Connected;

namespace Connected.Threading;

public class AsyncLocker : IDisposable
{
	private ConcurrentDictionary<int, AsyncLockerSlim> _items = new();
	private bool _disposed;

	private ConcurrentDictionary<int, AsyncLockerSlim> Items => _items;

	public async Task LockAsync(int semaphore, Func<Task> worker)
	{
		if (Items.TryGetValue(semaphore, out AsyncLockerSlim? locker))
			await locker.LockAsync(worker);

		var newLocker = new AsyncLockerSlim();

		if (Items.TryAdd(semaphore, newLocker))
			await newLocker.LockAsync(worker);
		else
		{
			newLocker.Dispose();

			if (!Items.TryGetValue(semaphore, out AsyncLockerSlim? existing))
				throw new SysException(this, SR.ErrLock);

			await existing.LockAsync(worker);
		}
	}

	public async Task<T> LockAsync<T>(int semaphore, Func<Task<T>> worker)
	{
		if (Items.TryGetValue(semaphore, out AsyncLockerSlim? locker))
			return await locker.LockAsync(worker);

		var newLocker = new AsyncLockerSlim();

		if (Items.TryAdd(semaphore, newLocker))
			return await newLocker.LockAsync(worker);
		else
		{
			newLocker.Dispose();

			if (!Items.TryGetValue(semaphore, out AsyncLockerSlim? existing))
				throw new SysException(this, SR.ErrLock);

			return await existing.LockAsync(worker);
		}
	}

	protected virtual void Dispose(bool disposing)
	{
		if (!_disposed)
		{
			if (disposing)
			{
				foreach (var slim in Items)
					slim.Value.Dispose();

				Items.Clear();
			}

			_disposed = true;
		}
	}

	public void Dispose()
	{
		Dispose(true);
		GC.SuppressFinalize(this);
	}
}