1 files changed, 81 insertions, 0 deletions
diff --git a/src/SMAPI/Framework/Events/ManagedEventBase.cs b/src/SMAPI/Framework/Events/ManagedEventBase.cs
new file mode 100644
index 00000000..cc4d89ec
--- /dev/null
+++ b/src/SMAPI/Framework/Events/ManagedEventBase.cs
@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace StardewModdingAPI.Framework.Events
+{
+    /// <summary>The base implementation for an event wrapper which intercepts and logs errors in handler code.</summary>
+    internal abstract class ManagedEventBase<TEventHandler>
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>A human-readable name for the event.</summary>
+        private readonly string EventName;
+
+        /// <summary>Writes messages to the log.</summary>
+        private readonly IMonitor Monitor;
+
+        /// <summary>The mod registry with which to identify mods.</summary>
+        private readonly ModRegistry ModRegistry;
+
+        /// <summary>The display names for the mods which added each delegate.</summary>
+        private readonly IDictionary<TEventHandler, IModMetadata> SourceMods = new Dictionary<TEventHandler, IModMetadata>();
+
+        /// <summary>The cached invocation list.</summary>
+        protected TEventHandler[] CachedInvocationList { get; private set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Get whether anything is listening to the event.</summary>
+        public bool HasListeners()
+        {
+            return this.CachedInvocationList?.Length > 0;
+        }
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="eventName">A human-readable name for the event.</param>
+        /// <param name="monitor">Writes messages to the log.</param>
+        /// <param name="modRegistry">The mod registry with which to identify mods.</param>
+        protected ManagedEventBase(string eventName, IMonitor monitor, ModRegistry modRegistry)
+        {
+            this.EventName = eventName;
+            this.Monitor = monitor;
+            this.ModRegistry = modRegistry;
+        }
+
+        /// <summary>Track an event handler.</summary>
+        /// <param name="handler">The event handler.</param>
+        /// <param name="invocationList">The updated event invocation list.</param>
+        protected void AddTracking(TEventHandler handler, IEnumerable<TEventHandler> invocationList)
+        {
+            this.SourceMods[handler] = this.ModRegistry.GetFromStack();
+            this.CachedInvocationList = invocationList.ToArray();
+        }
+
+        /// <summary>Remove tracking for an event handler.</summary>
+        /// <param name="handler">The event handler.</param>
+        /// <param name="invocationList">The updated event invocation list.</param>
+        protected void RemoveTracking(TEventHandler handler, IEnumerable<TEventHandler> invocationList)
+        {
+            this.SourceMods.Remove(handler);
+            this.CachedInvocationList = invocationList.ToArray();
+        }
+
+        /// <summary>Log an exception from an event handler.</summary>
+        /// <param name="handler">The event handler instance.</param>
+        /// <param name="ex">The exception that was raised.</param>
+        protected void LogError(TEventHandler handler, Exception ex)
+        {
+            if (this.SourceMods.TryGetValue(handler, out IModMetadata mod))
+                mod.LogAsMod($"This mod failed in the {this.EventName} event. Technical details: \n{ex.GetLogSummary()}", LogLevel.Error);
+            else
+                this.Monitor.Log($"A mod failed in the {this.EventName} event. Technical details: \n{ex.GetLogSummary()}", LogLevel.Error);
+        }
+    }
+}