mech bug fixes (#13155)

* mech bug fixes

* struct events

* fug

Content.Server/Tools/ToolSystem.cs

@@ -119,6 +119,11 @@ namespace Content.Server.Tools
             if (!Resolve(tool, ref toolComponent, false))
                 return false;
 
+            var ev = new ToolUserAttemptUseEvent(user, target);
+            RaiseLocalEvent(user, ref ev);
+            if (ev.Cancelled)
+                return false;
+
             if (!ToolStartUse(tool, user, fuel, toolQualitiesNeeded, toolComponent))
                 return false;
 
@@ -173,6 +178,11 @@ namespace Content.Server.Tools
             if (!Resolve(tool, ref toolComponent, false))
                 return false;
 
+            var ev = new ToolUserAttemptUseEvent(user, target);
+            RaiseLocalEvent(user, ref ev);
+            if (ev.Cancelled)
+                return false;
+
             if (!ToolStartUse(tool, user, fuel, toolQualitiesNeeded, toolComponent))
                 return false;
 
@@ -306,6 +316,23 @@ namespace Content.Server.Tools
         }
     }
 
+    /// <summary>
+    /// Event raised on the user of a tool to see if they can actually use it.
+    /// </summary>
+    [ByRefEvent]
+    public struct ToolUserAttemptUseEvent
+    {
+        public EntityUid User;
+        public EntityUid? Target;
+        public bool Cancelled = false;
+
+        public ToolUserAttemptUseEvent(EntityUid user, EntityUid? target)
+        {
+            User = user;
+            Target = target;
+        }
+    }
+
     /// <summary>
     ///     Attempt event called *after* any do afters to see if the tool usage should succeed or not.
     ///     You can use this event to consume any fuel needed.