1 files changed, 167 insertions, 0 deletions
diff --git a/Impostor-dev/src/Impostor.Server/Events/EventManager.cs b/Impostor-dev/src/Impostor.Server/Events/EventManager.cs
new file mode 100644
index 0000000..5625c4d
--- /dev/null
+++ b/Impostor-dev/src/Impostor.Server/Events/EventManager.cs
@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Impostor.Api;
+using Impostor.Api.Events;
+using Impostor.Api.Events.Managers;
+using Impostor.Server.Events.Register;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace Impostor.Server.Events
+{
+    internal class EventManager : IEventManager
+    {
+        private readonly ConcurrentDictionary<Type, TemporaryEventRegister> _temporaryEventListeners;
+        private readonly ConcurrentDictionary<Type, List<EventHandler>> _cachedEventHandlers;
+        private readonly ILogger<EventManager> _logger;
+        private readonly IServiceProvider _serviceProvider;
+
+        public EventManager(ILogger<EventManager> logger, IServiceProvider serviceProvider)
+        {
+            _logger = logger;
+            _serviceProvider = serviceProvider;
+            _temporaryEventListeners = new ConcurrentDictionary<Type, TemporaryEventRegister>();
+            _cachedEventHandlers = new ConcurrentDictionary<Type, List<EventHandler>>();
+        }
+
+        /// <inheritdoc />
+        public IDisposable RegisterListener<TListener>(TListener listener, Func<Func<Task>, Task> invoker = null)
+            where TListener : IEventListener
+        {
+            if (listener == null)
+            {
+                throw new ArgumentNullException(nameof(listener));
+            }
+
+            var eventListeners = RegisteredEventListener.FromType(listener.GetType());
+            var disposes = new IDisposable[eventListeners.Count];
+
+            foreach (var eventListener in eventListeners)
+            {
+                IRegisteredEventListener wrappedEventListener = new WrappedRegisteredEventListener(eventListener, listener);
+
+                if (invoker != null)
+                {
+                    wrappedEventListener = new InvokedRegisteredEventListener(wrappedEventListener, invoker);
+                }
+
+                var register = _temporaryEventListeners.GetOrAdd(
+                    wrappedEventListener.EventType,
+                    _ => new TemporaryEventRegister());
+
+                register.Add(wrappedEventListener);
+            }
+
+            if (eventListeners.Count > 0)
+            {
+                _cachedEventHandlers.TryRemove(typeof(TListener), out _);
+            }
+
+            return new MultiDisposable(disposes);
+        }
+
+        /// <inheritdoc />
+        public bool IsRegistered<TEvent>()
+            where TEvent : IEvent
+        {
+            if (_cachedEventHandlers.TryGetValue(typeof(TEvent), out var handlers))
+            {
+                return handlers.Count > 0;
+            }
+
+            return GetHandlers<TEvent>().Any();
+        }
+
+        /// <inheritdoc />
+        public async ValueTask CallAsync<T>(T @event)
+            where T : IEvent
+        {
+            try
+            {
+                if (!_cachedEventHandlers.TryGetValue(typeof(T), out var handlers))
+                {
+                    handlers = CacheEventHandlers<T>();
+                }
+
+                foreach (var (handler, eventListener) in handlers)
+                {
+                    await eventListener.InvokeAsync(handler, @event, _serviceProvider);
+                }
+            }
+            catch (ImpostorCheatException)
+            {
+                throw;
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Invocation of event {0} threw an exception.", @event.GetType().Name);
+            }
+        }
+
+        private List<EventHandler> CacheEventHandlers<TEvent>()
+            where TEvent : IEvent
+        {
+            var handlers = GetHandlers<TEvent>()
+                .OrderByDescending(e => e.Listener.Priority)
+                .ToList();
+
+            _cachedEventHandlers[typeof(TEvent)] = handlers;
+
+            return handlers;
+        }
+
+        /// <summary>
+        ///     Get all the event listeners for the given event type.
+        /// </summary>
+        /// <returns>The event listeners.</returns>
+        private IEnumerable<EventHandler> GetHandlers<TEvent>()
+            where TEvent : IEvent
+        {
+            var eventType = typeof(TEvent);
+            var interfaces = eventType.GetInterfaces();
+
+            foreach (var @interface in interfaces)
+            {
+                if (_temporaryEventListeners.TryGetValue(@interface, out var cb))
+                {
+                    foreach (var eventListener in cb.GetEventListeners())
+                    {
+                        yield return new EventHandler(null, eventListener);
+                    }
+                }
+            }
+
+            foreach (var handler in _serviceProvider.GetServices<IEventListener>())
+            {
+                if (handler is IManualEventListener manualEventListener && manualEventListener.CanExecute<TEvent>())
+                {
+                    yield return new EventHandler(handler, new ManualRegisteredEventListener(manualEventListener));
+                    continue;
+                }
+
+                var events = RegisteredEventListener.FromType(handler.GetType());
+
+                foreach (var eventHandler in events)
+                {
+                    if (eventHandler.EventType != typeof(TEvent) && !interfaces.Contains(eventHandler.EventType))
+                    {
+                        continue;
+                    }
+
+                    yield return new EventHandler(handler, eventHandler);
+                }
+            }
+
+            if (_temporaryEventListeners.TryGetValue(eventType, out var cb2))
+            {
+                foreach (var eventListener in cb2.GetEventListeners())
+                {
+                    yield return new EventHandler(null, eventListener);
+                }
+            }
+        }
+    }
+}