feat: 租户账单公告通知接口

src/Application/TakeoutSaaS.Application/App/Tenants/Handlers/GetTenantAnnouncementQueryHandler.cs

@@ -0,0 +1,28 @@
+using MediatR;
+using TakeoutSaaS.Application.App.Tenants.Dto;
+using TakeoutSaaS.Application.App.Tenants.Queries;
+using TakeoutSaaS.Domain.Tenants.Repositories;
+
+namespace TakeoutSaaS.Application.App.Tenants.Handlers;
+
+/// <summary>
+/// 公告详情查询处理器。
+/// </summary>
+public sealed class GetTenantAnnouncementQueryHandler(
+    ITenantAnnouncementRepository announcementRepository,
+    ITenantAnnouncementReadRepository readRepository)
+    : IRequestHandler<GetTenantAnnouncementQuery, TenantAnnouncementDto?>
+{
+    public async Task<TenantAnnouncementDto?> Handle(GetTenantAnnouncementQuery request, CancellationToken cancellationToken)
+    {
+        var announcement = await announcementRepository.FindByIdAsync(request.TenantId, request.AnnouncementId, cancellationToken);
+        if (announcement == null)
+        {
+            return null;
+        }
+
+        var reads = await readRepository.GetByAnnouncementAsync(request.TenantId, request.AnnouncementId, cancellationToken);
+        var readRecord = reads.FirstOrDefault();
+        return announcement.ToDto(readRecord != null, readRecord?.ReadAt);
+    }
+}