From c2a4877989c32f5124eb21080bb9081def2615d2 Mon Sep 17 00:00:00 2001
From: Chomp <dev@dev.sp-tarkov.com>
Date: Tue, 5 Aug 2025 16:30:53 +0100
Subject: [PATCH] Cleaned up `mergeItems()` logic

---
 .../SPT_Data/database/locales/server/en.json  |  2 +-
 .../Controllers/InventoryController.cs        | 49 ++++++++++---------
 2 files changed, 28 insertions(+), 23 deletions(-)

diff --git a/Libraries/SPTarkov.Server.Assets/SPT_Data/database/locales/server/en.json b/Libraries/SPTarkov.Server.Assets/SPT_Data/database/locales/server/en.json
index 4b48f202..952741a1 100644
--- a/Libraries/SPTarkov.Server.Assets/SPT_Data/database/locales/server/en.json
+++ b/Libraries/SPTarkov.Server.Assets/SPT_Data/database/locales/server/en.json
@@ -73,7 +73,7 @@
   "database-no_location_found_with_id": "No location found with an Id of: %s in database",
   "database-no_trader_found_with_id": "Unable to find trader: %s in database",
   "dialog-chatbot_id_already_exists": "Chat bot: %s being registered already exists, unable to register bot",
-  "dialog-missing_item_template": "Unable to find item tpl {{tpl}} in db, cannot send message of type {{type}}, skipping",
+  "dialog-missing_item_template": "Unable to find item tpl: {{tpl}} in db, cannot send message of type: {{type}}, skipping",
   "dialogue-unable_to_find_dialogs_in_profile": "No dialog object in profile: {{sessionId}}",
   "dialogue-list_from_client_empty": "No dialog object sent from client: {{sessionId}}",
   "dialogue-unable_to_find_in_profile": "No dialog in profile: {{sessionId}} found with id: {{dialogueId}}",
diff --git a/Libraries/SPTarkov.Server.Core/Controllers/InventoryController.cs b/Libraries/SPTarkov.Server.Core/Controllers/InventoryController.cs
index 7d4431ba..028256ce 100644
--- a/Libraries/SPTarkov.Server.Core/Controllers/InventoryController.cs
+++ b/Libraries/SPTarkov.Server.Core/Controllers/InventoryController.cs
@@ -816,7 +816,7 @@ public class InventoryController(
     /// <param name="output">Client response</param>
     public void MergeItem(PmcData pmcData, InventoryMergeRequestData request, MongoId sessionID, ItemEventRouterResponse output)
     {
-        // Changes made to result apply to character inventory
+        // Get source and destination inventories, they are not always the same (e.g. moving post-raid scav item stack into pmc inventory stack)
         var inventoryItems = inventoryHelper.GetOwnerInventoryItems(request, request.Item, sessionID);
 
         // Get source item (can be from player or trader or mail)
@@ -843,43 +843,48 @@ public class InventoryController(
             return;
         }
 
-        if (destinationItem.Upd?.StackObjectsCount is null)
-        // No stackcount on destination, add one
-        {
-            destinationItem.Upd = new Upd { StackObjectsCount = 1 };
-        }
+        EnsureItemHasValidStackCount(destinationItem);
+        EnsureItemHasValidStackCount(sourceItem);
 
-        if (sourceItem.Upd is null)
-        {
-            sourceItem.Upd = new Upd { StackObjectsCount = 1 };
-        }
-        else if (sourceItem.Upd.StackObjectsCount is null)
-        // Items pulled out of raid can have no stack count if the stack should be 1
-        {
-            sourceItem.Upd.StackObjectsCount = 1;
-        }
-
-        // Remove FiR status from destination stack when source stack has no FiR but destination does
+        // Merging non Found in Raid (SpawnedInSession) items with FiR item causing result to be not Found in Raid
         if (!sourceItem.Upd.SpawnedInSession.GetValueOrDefault(false) && destinationItem.Upd.SpawnedInSession.GetValueOrDefault(false))
         {
             destinationItem.Upd.SpawnedInSession = false;
         }
 
-        destinationItem.Upd.StackObjectsCount += sourceItem.Upd.StackObjectsCount; // Add source stackcount to destination
+        // Add source stackcount to destination
+        destinationItem.Upd.StackObjectsCount += sourceItem.Upd.StackObjectsCount;
+
+        // Update output to inform client of source stack being deleted
         output.ProfileChanges[sessionID].Items.DeletedItems.Add(new DeletedItem { Id = sourceItem.Id }); // Inform client source item being deleted
 
-        var indexOfItemToRemove = inventoryItems.From.FindIndex(x => x.Id == sourceItem.Id);
-        if (indexOfItemToRemove == -1)
+        // Remove source item from server profile now it has been merged into destination item
+        if (!inventoryItems.From.Remove(sourceItem))
         {
             var errorMessage = $"Unable to find item: {sourceItem.Id} to remove from sender inventory";
             logger.Error(errorMessage);
 
             httpResponseUtil.AppendErrorToOutput(output, errorMessage);
+        }
+    }
 
-            return;
+    /// <summary>
+    /// Ensure an item has a upd object with a stack count of 1
+    /// </summary>
+    /// <param name="item">Item to check</param>
+    protected void EnsureItemHasValidStackCount(Item item)
+    {
+        if (item.Upd is null)
+        {
+            item.AddUpd();
+            item.Upd.StackObjectsCount = 1;
         }
 
-        inventoryItems.From.RemoveAt(indexOfItemToRemove); // Remove source item from 'from' inventory
+        if (item.Upd.StackObjectsCount is null or 0)
+        {
+            // Items pulled out of raid can have no stack count, default to 1
+            item.Upd.StackObjectsCount = 1;
+        }
     }
 
     /// <summary>