feat(store): auto-generate store code on create and make update code optional

src/Application/TakeoutSaaS.Application/App/Stores/Handlers/CreateStoreCommandHandler.cs

@@ -1,4 +1,5 @@
 using MediatR;
+using System.Security.Cryptography;
 using TakeoutSaaS.Application.App.Stores.Commands;
 using TakeoutSaaS.Application.App.Stores.Enums;
 using TakeoutSaaS.Application.App.Stores.Services;
@@ -24,7 +25,7 @@ public sealed class CreateStoreCommandHandler(
         // 1. 解析上下文
         var context = storeContextService.GetRequiredContext();
 
-        // 2. 校验编码唯一性
+        // 2. 生成唯一门店编码
         var existingStores = await storeRepository.SearchAsync(
             context.TenantId,
             context.MerchantId,
@@ -35,12 +36,7 @@ public sealed class CreateStoreCommandHandler(
             keyword: null,
             includeDeleted: false,
             cancellationToken: cancellationToken);
-        var normalizedCode = request.Code.Trim();
-        var hasDuplicateCode = existingStores.Any(store => string.Equals(store.Code, normalizedCode, StringComparison.OrdinalIgnoreCase));
-        if (hasDuplicateCode)
-        {
-            throw new BusinessException(ErrorCodes.Conflict, "门店编码已存在");
-        }
+        var generatedCode = GenerateUniqueStoreCode(existingStores);
 
         // 3. 组装门店实体
         var serviceTypes = request.ServiceTypes?.Count > 0
@@ -50,7 +46,7 @@ public sealed class CreateStoreCommandHandler(
         {
             TenantId = context.TenantId,
             MerchantId = context.MerchantId,
-            Code = normalizedCode,
+            Code = generatedCode,
             Name = request.Name.Trim(),
             Phone = request.ContactPhone.Trim(),
             ManagerName = request.ManagerName.Trim(),
@@ -68,4 +64,27 @@ public sealed class CreateStoreCommandHandler(
         await storeRepository.AddStoreAsync(store, cancellationToken);
         await storeRepository.SaveChangesAsync(cancellationToken);
     }
+
+    /// <summary>
+    /// 生成当前租户商户内唯一的门店编码。
+    /// </summary>
+    private static string GenerateUniqueStoreCode(IReadOnlyList<Store> existingStores)
+    {
+        var existingCodeSet = existingStores
+            .Select(store => store.Code.Trim())
+            .Where(code => !string.IsNullOrWhiteSpace(code))
+            .ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        const int maxRetryCount = 20;
+        for (var attempt = 0; attempt < maxRetryCount; attempt++)
+        {
+            var candidate = $"ST{DateTime.UtcNow:yyMMddHHmmss}{RandomNumberGenerator.GetInt32(100, 1000)}";
+            if (existingCodeSet.Add(candidate))
+            {
+                return candidate;
+            }
+        }
+
+        throw new BusinessException(ErrorCodes.Conflict, "门店编码生成失败，请稍后重试");
+    }
 }