feat(生產/庫存): 實作生產管理模組與批號追溯功能

app/Models/Inventory.php

@@ -17,6 +17,20 @@ class Inventory extends Model
         'quantity',
         'safety_stock',
         'location',
+        // 批號追溯欄位
+        'batch_number',
+        'box_number',
+        'origin_country',
+        'arrival_date',
+        'expiry_date',
+        'source_purchase_order_id',
+        'quality_status',
+        'quality_remark',
+    ];
+
+    protected $casts = [
+        'arrival_date' => 'date:Y-m-d',
+        'expiry_date' => 'date:Y-m-d',
     ];
 
     /**
@@ -89,4 +103,35 @@ class Inventory extends Model
             $query->where('quantity', '>', 0);
         });
     }
+
+    /**
+     * 來源採購單
+     */
+    public function sourcePurchaseOrder(): \Illuminate\Database\Eloquent\Relations\BelongsTo
+    {
+        return $this->belongsTo(PurchaseOrder::class, 'source_purchase_order_id');
+    }
+
+    /**
+     * 產生批號
+     * 格式：{商品代號}-{來源國家}-{入庫日期}-{批次流水號}
+     */
+    public static function generateBatchNumber(string $productCode, string $originCountry, string $arrivalDate): string
+    {
+        $dateFormatted = date('Ymd', strtotime($arrivalDate));
+        $prefix = "{$productCode}-{$originCountry}-{$dateFormatted}-";
+
+        $lastBatch = static::where('batch_number', 'like', "{$prefix}%")
+            ->orderByDesc('batch_number')
+            ->first();
+
+        if ($lastBatch) {
+            $lastNumber = (int) substr($lastBatch->batch_number, -2);
+            $nextNumber = str_pad($lastNumber + 1, 2, '0', STR_PAD_LEFT);
+        } else {
+            $nextNumber = '01';
+        }
+
+        return $prefix . $nextNumber;
+    }
 }