Added message count endpoint

src/Web/Features/Messages/Data/MessagingDbContext.cs

@@ -56,4 +56,21 @@ public class MessagingDbContext(
 
         return messages;
     }
+    
+    public async Task<int> GetMessageCountAsync(
+        Guid subjectId,
+        Guid? parentId,
+        int pageSize,
+        CancellationToken ct = default)
+    {
+        var query = Messages
+            .Where(c => c.SubjectId == subjectId)
+            .Where(c => c.ParentId == parentId);
+
+        var messageCount = await query
+            .Take(pageSize)
+            .CountAsync(ct);
+
+        return messageCount;
+    }
 }

src/Web/Features/Messages/Handlers/GetMessageCount.cs

@@ -0,0 +1,44 @@
+using Hutopy.Web.Features.Messages.Data;
+
+namespace Hutopy.Web.Features.Messages.Handlers;
+
+public sealed class GetMessageCountRequest
+{
+    public Guid SubjectId { get; set; }
+    [BindFrom("page_size")] public int PageSize { get; set; } = 1000;
+}
+
+public record struct GetMessageCountResponse
+{
+    public required int Count { get; init; }
+}
+
+public class GetMessageCount(
+    MessagingDbContext context)
+    : Endpoint<GetMessageCountRequest, GetMessageCountResponse>
+{
+    public override void Configure()
+    {
+        Get("/api/message-count/{SubjectId:guid}");
+        Options(o => o.WithTags("Messages"));
+        AllowAnonymous();
+    }
+
+    public override async Task HandleAsync(
+        GetMessageCountRequest req,
+        CancellationToken ct)
+    {
+        var messageCount = await context.GetMessageCountAsync(
+            req.SubjectId,
+            null,
+            req.PageSize,
+            ct);
+        
+        await SendAsync(
+            new()
+            {
+                Count = messageCount
+            },
+            cancellation: ct);
+    }
+}