diff --git a/app/Http/Controllers/PdfController.php b/app/Http/Controllers/PdfController.php
index 3e15219..5f29047 100644
--- a/app/Http/Controllers/PdfController.php
+++ b/app/Http/Controllers/PdfController.php
@@ -3,6 +3,7 @@
 namespace App\Http\Controllers;
 
 use App\Models\GrMaster;
+use App\Models\Item;
 use App\Models\Plant;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Response;
@@ -18,6 +19,187 @@ class PdfController extends Controller
     {
         //
     }
+    public function updateGR(Request $request)
+    {
+        $expectedUser = env('API_AUTH_USER');
+        $expectedPw   = env('API_AUTH_PW');
+
+        $header_auth = $request->header('Authorization');
+        $expectedToken = $expectedUser . ':' . $expectedPw;
+
+        if ("Bearer " . $expectedToken != $header_auth)
+        {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Invalid authorization token!'
+            ], 403);
+        }
+
+        $data = $request->all();
+
+        if ($data['plant_code'] == null || $data['plant_code'] == '')
+        {
+            // return response("ERROR: Please provide a valid plant code.", 400)
+            //     ->header('Content-Type', 'text/plain');
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => "Plant code can't be empty!"
+            ], 400);
+        }
+        else if (Str::length($data['plant_code']) < 4 || !is_numeric($data['plant_code']) || !preg_match('/^[1-9]\d{3,}$/', $data['plant_code']))//!ctype_digit($data['plant_code'])
+        {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => "Invalid plant code found!"
+            ], 400);
+        }
+
+        $plant = Plant::where('code', $data['plant_code'])->first();
+        if (!$plant) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Plant not found!'
+            ], 400);
+        }
+
+        $plantId = $plant->id;
+        if ($data['gr_number'] == null || $data['gr_number'] == '')
+        {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => "GR Number can't be empty!"
+            ], 400);
+        }
+
+        $scannedBy = $data['scanned_by'] ?? null;
+
+        if ($scannedBy == '' || $scannedBy == null) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => "Scanned by can't be empty!"
+            ], 400);
+        }
+
+        $itemCodes = array_column($data['item_codes'], 'item_code');
+
+        $duplicateItemCodes = array_unique(array_diff_assoc($itemCodes, array_unique($itemCodes)));
+
+        if (count($duplicateItemCodes) > 0) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Duplicate item codes found in request!',
+                'duplicate_item_codes' => array_values($duplicateItemCodes)
+            ], 400);
+        }
+
+        $allSerials = [];
+        foreach ($data['item_codes'] as $item) {
+            if (!isset($item['serial_numbers']) || !is_array($item['serial_numbers'])) {
+                continue;
+            }
+            foreach ($item['serial_numbers'] as $serial) {
+                $allSerials[] = $serial;
+            }
+        }
+
+        $duplicateSerials = array_unique(array_diff_assoc($allSerials, array_unique($allSerials)));
+
+        if (count($duplicateSerials) > 0) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Duplicate serial numbers found in request!',
+                'duplicate_serial_numbers' => array_values($duplicateSerials)
+            ], 400);
+        }
+
+        $invalidItemCodes = [];
+        $invalidPlantItems = [];
+
+        foreach ($data['item_codes'] as $item)
+        {
+            $itemCode = $item['item_code'] ?? null;
+
+            if (!$itemCode) {
+                $invalidItemCodes[] = "(missing)";
+                continue;
+            }
+
+            $itemObj = Item::where('code', $itemCode)->first();
+            if (!$itemObj) {
+                $invalidItemCodes[] = $itemCode;
+                continue;
+            }
+
+            $itemPlant = Item::where('plant_id', $plantId)
+                ->where('code', $itemCode)->first();
+            if (!$itemPlant) {
+                $invalidPlantItems[] = $itemCode;
+            }
+        }
+
+        if (count($invalidItemCodes) > 0 || count($invalidPlantItems) > 0) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Some item codes are invalid!',
+                'not_found_items' => array_values($invalidItemCodes),
+                'not_in_plant' => array_values($invalidPlantItems)
+            ], 400);
+        }
+
+        // foreach ($data['item_codes'] as $item)
+        // {
+        //     $itemCode = $item['item_code'];
+        //     $serialNumbers = $item['serial_numbers'];
+
+        //     $itemObj = Item::where('code', $itemCode)->first();
+        //     if (!$itemObj) {
+        //         return response()->json([
+        //             'status_code' => 'ERROR',
+        //             'status_description' => "Item code: $itemCode not found"
+        //         ], 400);
+        //     }
+
+        //     $itemPlant = Item::where('plant_id', $plantId)
+        //     ->where('code', $itemCode)->first();
+        //     if (!$itemPlant) {
+        //         return response()->json([
+        //             'status_code' => 'ERROR',
+        //             'status_description' => "Item code: $itemCode not found for the plant: $data[plant_code]"
+        //         ], 400);
+        //     }
+
+
+        //     $itemId = $itemObj->id;
+
+        //     // Update all serial numbers for this item
+        //     GRMaster::where('plant_id', $plantId)
+        //         ->where('item_id', $itemId)
+        //         ->where('gr_number', $data['gr_number'])
+        //         ->whereIn('serial_number', $serialNumbers)
+        //         ->update(['created_by' => $scannedBy]);
+        // }
+
+
+        foreach ($data['item_codes'] as $item)
+        {
+            $itemCode = $item['item_code'];
+            $serialNumbers = $item['serial_numbers'];
+
+            $itemId = Item::where('code', $itemCode)->value('id');
+
+            GRMaster::where('plant_id', $plantId)
+                ->where('item_id', $itemId)
+                ->where('gr_number', $data['gr_number'])
+                ->whereIn('serial_number', $serialNumbers)
+                ->update(['created_by' => $scannedBy]);
+        }
+
+        return response()->json([
+            'status_code' => 'SUCCESS',
+            'status_description' => 'Serial numbers updated successfully!'
+        ], 200);
+
+    }
 
     /**
      * Store a newly created resource in storage.
@@ -200,8 +382,6 @@ class PdfController extends Controller
         return response()->json([
             'serial_numbers' => $serialNumbers
         ], 200);
-
-
     }