PeerConnectiveChat/PCC2.Shared/EventBus/InProcessAsyncEventBusBase.cs

namespace PCC2.EventBus;

public abstract class InProcessAsyncEventBusBase(ILogger<InProcessAsyncEventBusBase> logger) : IAsyncEventBus
{
    private readonly Dictionary<Type, HashSet<Delegate>> _dicTypeToHandlers = [];

    public bool Subscript<T>(Func<T, Task> callBack)
    {
        var type = typeof(T);
        lock (_dicTypeToHandlers)
        {
            if (!_dicTypeToHandlers.TryGetValue(type, out var handlers))
            {
                handlers = _dicTypeToHandlers[type] = [];
            }

            return handlers.Add(callBack); // 忽略重复
        }
    }

    public bool UnSubscript<T>(Func<T, Task> callBack)
    {
        lock (_dicTypeToHandlers)
        {
            if (_dicTypeToHandlers.TryGetValue(typeof(T), out var handlers))
            {
                var unSubscript = handlers.Remove(callBack);

                if (handlers.Count == 0) _dicTypeToHandlers.Remove(typeof(T));

                return unSubscript;
            }

            return false;
        }
    }

    public async Task<bool> PublishAsync<T>()
    {
        await PublishInternalAsync(new AnyPublishEvent(typeof(T), default));
        return await PublishInternalAsync<T?>(default);
    }

    public async Task<bool> PublishAsync<T>(T obj)
    {
        await PublishInternalAsync(new AnyPublishEvent(typeof(T), obj));
        return await PublishInternalAsync(obj);
    }

    private async Task<bool> PublishInternalAsync<T>(T eventValue)
    {
        var type = typeof(T);

        Delegate[] subscripts;
        lock (_dicTypeToHandlers)
        {
            if (!_dicTypeToHandlers.TryGetValue(type, out var handlers)) return false;
            subscripts = [.. handlers];
        }

        foreach (var del in subscripts)
        {
            try
            {
                await ((Func<T, Task>)del)(eventValue);
            }
            catch (Exception e)
            {
                logger.LogError(e, nameof(PublishAsync));
            }
        }

        return true;
    }
}