From 38a8a22e5acaa8b90948025dc56e32e794fe940e Mon Sep 17 00:00:00 2001
From: Rane <60792108+Elijahrane@users.noreply.github.com>
Date: Wed, 27 Jul 2022 19:28:23 -0400
Subject: [PATCH] Throwing event improvements (#10055)

---
 Content.Server/Hands/Systems/HandsSystem.cs   | 20 ++++++++++++++-----
 .../ActionBlocker/ActionBlockerSystem.cs      |  4 ++--
 Content.Shared/Throwing/BeforeThrowEvent.cs   | 18 +++++++++++++++++
 Content.Shared/Throwing/ThrowAttemptEvent.cs  |  5 ++++-
 4 files changed, 39 insertions(+), 8 deletions(-)
 create mode 100644 Content.Shared/Throwing/BeforeThrowEvent.cs

diff --git a/Content.Server/Hands/Systems/HandsSystem.cs b/Content.Server/Hands/Systems/HandsSystem.cs
index 5f8ee7dd42..ae73a9ebc6 100644
--- a/Content.Server/Hands/Systems/HandsSystem.cs
+++ b/Content.Server/Hands/Systems/HandsSystem.cs
@@ -190,7 +190,7 @@ namespace Content.Server.Hands.Systems
                 player.IsInContainer() ||
                 !TryComp(player, out SharedHandsComponent? hands) ||
                 hands.ActiveHandEntity is not EntityUid throwEnt ||
-                !_actionBlockerSystem.CanThrow(player))
+                !_actionBlockerSystem.CanThrow(player, throwEnt))
                 return false;
 
             if (EntityManager.TryGetComponent(throwEnt, out StackComponent? stack) && stack.Count > 1 && stack.ThrowIndividually)
@@ -202,8 +202,6 @@ namespace Content.Server.Hands.Systems
 
                 throwEnt = splitStack.Value;
             }
-            else if (!TryDrop(player, throwEnt, handsComp: hands))
-                return false;
 
             var direction = coords.ToMapPos(EntityManager) - Transform(player).WorldPosition;
             if (direction == Vector2.Zero)
@@ -212,11 +210,23 @@ namespace Content.Server.Hands.Systems
             direction = direction.Normalized * Math.Min(direction.Length, hands.ThrowRange);
 
             var throwStrength = hands.ThrowForceMultiplier;
-            _throwingSystem.TryThrow(throwEnt, direction, throwStrength, player);
+
+            // Let other systems change the thrown entity (useful for virtual items)
+            // or the throw strength.
+            var ev = new BeforeThrowEvent(throwEnt, direction, throwStrength, player);
+            RaiseLocalEvent(player, ev, false);
+
+            if (ev.Handled)
+                return true;
+
+            // This can grief the above event so we raise it afterwards
+            if (!TryDrop(player, throwEnt, handsComp: hands))
+                return false;
+
+            _throwingSystem.TryThrow(ev.ItemUid, ev.Direction, ev.ThrowStrength, ev.PlayerUid);
 
             return true;
         }
-
         private void HandleSmartEquipBackpack(ICommonSession? session)
         {
             HandleSmartEquip(session, "back");
diff --git a/Content.Shared/ActionBlocker/ActionBlockerSystem.cs b/Content.Shared/ActionBlocker/ActionBlockerSystem.cs
index f2e47ad8eb..3c0161f2f5 100644
--- a/Content.Shared/ActionBlocker/ActionBlockerSystem.cs
+++ b/Content.Shared/ActionBlocker/ActionBlockerSystem.cs
@@ -97,9 +97,9 @@ namespace Content.Shared.ActionBlocker
             return !ev.Cancelled;
         }
 
-        public bool CanThrow(EntityUid user)
+        public bool CanThrow(EntityUid user, EntityUid itemUid)
         {
-            var ev = new ThrowAttemptEvent(user);
+            var ev = new ThrowAttemptEvent(user, itemUid);
             RaiseLocalEvent(user, ev, true);
 
             return !ev.Cancelled;
diff --git a/Content.Shared/Throwing/BeforeThrowEvent.cs b/Content.Shared/Throwing/BeforeThrowEvent.cs
new file mode 100644
index 0000000000..349a18c56d
--- /dev/null
+++ b/Content.Shared/Throwing/BeforeThrowEvent.cs
@@ -0,0 +1,18 @@
+namespace Content.Shared.Throwing
+{
+    public sealed class BeforeThrowEvent : HandledEntityEventArgs
+    {
+        public BeforeThrowEvent(EntityUid itemUid, Vector2 direction, float throwStrength,  EntityUid playerUid)
+        {
+           ItemUid = itemUid;
+           Direction = direction;
+           ThrowStrength = throwStrength;
+           PlayerUid = playerUid;
+        }
+
+        public EntityUid ItemUid { get; set; }
+        public Vector2 Direction { get; }
+        public float ThrowStrength { get; set;}
+        public EntityUid PlayerUid { get; }
+    }
+}
diff --git a/Content.Shared/Throwing/ThrowAttemptEvent.cs b/Content.Shared/Throwing/ThrowAttemptEvent.cs
index 23ef048b0a..bf8cad6c74 100644
--- a/Content.Shared/Throwing/ThrowAttemptEvent.cs
+++ b/Content.Shared/Throwing/ThrowAttemptEvent.cs
@@ -2,12 +2,15 @@
 {
     public sealed class ThrowAttemptEvent : CancellableEntityEventArgs
     {
-        public ThrowAttemptEvent(EntityUid uid)
+        public ThrowAttemptEvent(EntityUid uid, EntityUid itemUid)
         {
             Uid = uid;
+            ItemUid = itemUid;
         }
 
         public EntityUid Uid { get; }
+
+        public EntityUid ItemUid { get; }
     }
 
     /// <summary>