♻️ Refactor the last read at system of chat

DysonNetwork.Sphere/Chat/ChatController.cs

@@ -15,7 +15,6 @@ public partial class ChatController(AppDatabase db, ChatService cs) : Controller
 {
     public class MarkMessageReadRequest
     {
-        public Guid MessageId { get; set; }
         public Guid ChatRoomId { get; set; }
     }
     

DysonNetwork.Sphere/Chat/ChatRoom.cs

@@ -63,6 +63,7 @@ public class ChatMember : ModelBase
 
     public ChatMemberRole Role { get; set; } = ChatMemberRole.Member;
     public ChatMemberNotify Notify { get; set; } = ChatMemberNotify.All;
+    public Instant? LastReadAt { get; set; }
     public Instant? JoinedAt { get; set; }
     public Instant? LeaveAt { get; set; }
     public bool IsBot { get; set; } = false;

DysonNetwork.Sphere/Chat/ChatService.cs

@@ -63,73 +63,54 @@ public class ChatService(AppDatabase db, FileService fs, IServiceScopeFactory sc
         await Task.WhenAll(tasks);
     }
 
-    public async Task MarkMessageAsReadAsync(Guid messageId, Guid roomId, Guid userId)
+    /// <summary>
+    /// This method will instant update the LastReadAt field for chat member,
+    /// for better performance, using the flush buffer one instead
+    /// </summary>
+    /// <param name="roomId">The user chat room</param>
+    /// <param name="userId">The user id</param>
+    /// <exception cref="ArgumentException"></exception>
+    public async Task ReadChatRoomAsync(Guid roomId, Guid userId)
     {
-        var existingStatus = await db.ChatReadReceipts
-            .FirstOrDefaultAsync(x => x.MessageId == messageId && x.Sender.AccountId == userId);
         var sender = await db.ChatMembers
             .Where(m => m.AccountId == userId && m.ChatRoomId == roomId)
             .FirstOrDefaultAsync();
         if (sender is null) throw new ArgumentException("User is not a member of the chat room.");
 
-        if (existingStatus == null)
-        {
-            existingStatus = new MessageReadReceipt
-            {
-                MessageId = messageId,
-                SenderId = sender.Id,
-            };
-            db.ChatReadReceipts.Add(existingStatus);
-        }
-
+        sender.LastReadAt = SystemClock.Instance.GetCurrentInstant();
         await db.SaveChangesAsync();
     }
 
-    public async Task<bool> GetMessageReadStatus(Guid messageId, Guid userId)
-    {
-        return await db.ChatReadReceipts
-            .AnyAsync(x => x.MessageId == messageId && x.Sender.AccountId == userId);
-    }
-
     public async Task<int> CountUnreadMessage(Guid userId, Guid chatRoomId)
     {
-        var cutoff = SystemClock.Instance.GetCurrentInstant().Minus(Duration.FromDays(30));
-        var messages = await db.ChatMessages
-            .Where(m => m.ChatRoomId == chatRoomId)
-            .Where(m => m.CreatedAt < cutoff)
-            .Select(m => new MessageStatusResponse
-            {
-                MessageId = m.Id,
-                IsRead = m.Statuses.Any(rs => rs.Sender.AccountId == userId)
-            })
-            .ToListAsync();
+        var sender = await db.ChatMembers
+            .Where(m => m.AccountId == userId && m.ChatRoomId == chatRoomId)
+            .Select(m => new { m.LastReadAt })
+            .FirstOrDefaultAsync();
+        if (sender?.LastReadAt is null) return 0;
 
-        return messages.Count(m => !m.IsRead);
+        return await db.ChatMessages
+            .Where(m => m.ChatRoomId == chatRoomId)
+            .Where(m => m.CreatedAt > sender.LastReadAt)
+            .CountAsync();
     }
 
     public async Task<Dictionary<Guid, int>> CountUnreadMessageForUser(Guid userId)
     {
-        var cutoff = SystemClock.Instance.GetCurrentInstant().Minus(Duration.FromDays(30));
-        var userRooms = await db.ChatMembers
+        var members = await db.ChatMembers
             .Where(m => m.AccountId == userId)
-            .Select(m => m.ChatRoomId)
+            .Select(m => new { m.ChatRoomId, m.LastReadAt })
             .ToListAsync();
-
-        var messages = await db.ChatMessages
-            .Where(m => m.CreatedAt < cutoff)
-            .Where(m => userRooms.Contains(m.ChatRoomId))
-            .Select(m => new
-            {
-                m.ChatRoomId,
-                IsRead = m.Statuses.Any(rs => rs.Sender.AccountId == userId)
-            })
-            .ToListAsync();
-
-        return messages
+    
+        var lastReadAt = members.ToDictionary(m => m.ChatRoomId, m => m.LastReadAt);
+        var roomsId = lastReadAt.Keys.ToList();
+        
+        return await db.ChatMessages
+            .Where(m => roomsId.Contains(m.ChatRoomId))
             .GroupBy(m => m.ChatRoomId)
-            .ToDictionary(
+            .ToDictionaryAsync(
                 g => g.Key,
-                g => g.Count(m => !m.IsRead)
+                g => g.Count(m => lastReadAt[g.Key] == null || m.CreatedAt > lastReadAt[g.Key])
             );
     }
 

DysonNetwork.Sphere/Chat/Message.cs

@@ -10,7 +10,7 @@ namespace DysonNetwork.Sphere.Chat;
 public class Message : ModelBase
 {
     public Guid Id { get; set; } = Guid.NewGuid();
-    public string Type { get; set; } = null!;
+    [MaxLength(1024)] public string Type { get; set; } = null!;
     [MaxLength(4096)] public string? Content { get; set; }
     [Column(TypeName = "jsonb")] public Dictionary<string, object>? Meta { get; set; }
     [Column(TypeName = "jsonb")] public List<Guid>? MembersMentioned { get; set; }
@@ -19,7 +19,6 @@ public class Message : ModelBase
 
     public ICollection<CloudFile> Attachments { get; set; } = new List<CloudFile>();
     public ICollection<MessageReaction> Reactions { get; set; } = new List<MessageReaction>();
-    public ICollection<MessageReadReceipt> Statuses { get; set; } = new List<MessageReadReceipt>();
 
     public Guid? RepliedMessageId { get; set; }
     public Message? RepliedMessage { get; set; }
@@ -43,7 +42,6 @@ public class Message : ModelBase
             EditedAt = EditedAt,
             Attachments = new List<CloudFile>(Attachments),
             Reactions = new List<MessageReaction>(Reactions),
-            Statuses = new List<MessageReadReceipt>(Statuses),
             RepliedMessageId = RepliedMessageId,
             RepliedMessage = RepliedMessage?.Clone() as Message,
             ForwardedMessageId = ForwardedMessageId,
@@ -78,19 +76,13 @@ public class MessageReaction : ModelBase
     public MessageReactionAttitude Attitude { get; set; }
 }
 
-/// If the status exists, means the user has read the message.
-[Index(nameof(MessageId), nameof(SenderId), IsUnique = true)]
-public class MessageReadReceipt : ModelBase
-{
-    public Guid MessageId { get; set; }
-    public Message Message { get; set; } = null!;
-    public Guid SenderId { get; set; }
-    public ChatMember Sender { get; set; } = null!;
-}
-
+/// <summary>
+/// The data model for updating the last read at field for chat member,
+/// after the refactor of the unread system, this no longer stored in the database.
+/// Not only used for the data transmission object
+/// </summary>
 [NotMapped]
-public class MessageStatusResponse
+public class MessageReadReceipt
 {
-    public Guid MessageId { get; set; }
-    public bool IsRead { get; set; }
+    public Guid SenderId { get; set; }
 }