更新若干功能

app/Service/business/StockService.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Service\business;
+
+use App\Models\business\PriceSheetModel;
+use App\Service\common\UtilsService;
+
+/**
+ * 规格库存：stock=-1 表示不限，兼容历史数据全是不限。
+ */
+class StockService
+{
+    private static mixed $_instance;
+
+    public static function getInstance(): null|static
+    {
+        $name = get_called_class();
+        if (!isset(self::$_instance[$name])) {
+            self::$_instance[$name] = new static();
+        }
+        return self::$_instance[$name];
+    }
+
+    /**
+     * 加入清单 / 下单前校验。sheetId=0 时跳过（还没选规格）。
+     */
+    public function assertAvailable(int $sheetId, int $quantity): void
+    {
+        if ($sheetId <= 0) {
+            return;
+        }
+        $sheet = PriceSheetModel::where('id', $sheetId)->where('deleted_at', 0)->first();
+        if (empty($sheet)) {
+            UtilsService::getInstance()->errorThrow('规格不存在');
+        }
+        $stock = (int) ($sheet['stock'] ?? -1);
+        if ($stock < 0) {
+            return;
+        }
+        if ($stock < $quantity) {
+            UtilsService::getInstance()->errorThrow('库存不足（剩余 ' . $stock . '）');
+        }
+    }
+
+    /**
+     * 下单成功后扣库存；不限库存不写库。
+     */
+    public function deduct(int $sheetId, int $quantity): void
+    {
+        if ($sheetId <= 0 || $quantity <= 0) {
+            return;
+        }
+        $sheet = PriceSheetModel::where('id', $sheetId)->where('deleted_at', 0)->first();
+        if (empty($sheet)) {
+            return;
+        }
+        $stock = (int) ($sheet['stock'] ?? -1);
+        if ($stock < 0) {
+            return;
+        }
+        $next = max(0, $stock - $quantity);
+        PriceSheetModel::where('id', $sheetId)->update([
+            'stock' => $next,
+            'updated_at' => time(),
+        ]);
+    }
+}