feat: support OnLastDeliveredAt, OnLastReadAt

Realtime/Realtime/Conversation/LCIMConversationQuery.cs

@@ -2,6 +2,9 @@
 using System.Collections;
 using System.Collections.ObjectModel;
 using LeanCloud.Storage.Internal.Query;
+using System.Linq;
+using System.Collections.Generic;
+using System;
 
 namespace LeanCloud.Realtime {
     public class LCIMConversationQuery {
@@ -274,5 +277,15 @@ namespace LeanCloud.Realtime {
         public async Task<ReadOnlyCollection<LCIMConversation>> Find() {
             return await client.ConversationController.Find(this);
         }
+
+        /// <summary>
+        /// Retrieves the first conversation from the query.
+        /// </summary>
+        /// <returns></returns>
+        public async Task<LCIMConversation> First() {
+            Limit(1);
+            ReadOnlyCollection<LCIMConversation> conversations = await Find();
+            return conversations?.First();
+        }
     }
 }

Realtime/Realtime/Internal/Controller/LCIMMessageController.cs

@@ -285,8 +285,16 @@ namespace LeanCloud.Realtime.Internal.Controller {
             LCIMConversation conversation = await Client.GetOrQueryConversation(convId);
             if (isRead) {
                 Client.OnMessageRead?.Invoke(conversation, msgId);
+                if (timestamp > conversation.LastReadTimestamp) {
+                    conversation.LastReadTimestamp = timestamp;
+                    Client.OnLastReadAtUpdated?.Invoke(conversation);
+                }
             } else {
                 Client.OnMessageDelivered?.Invoke(conversation, msgId);
+                if (timestamp > conversation.LastDeliveredTimestamp) {
+                    conversation.LastDeliveredTimestamp = timestamp;
+                    Client.OnLastDeliveredAtUpdated?.Invoke(conversation);
+                }
             }
         }
 

Realtime/Realtime/LCIMClient.cs

@@ -204,14 +204,14 @@ namespace LeanCloud.Realtime {
         /// <summary>
         /// Occurs when the last delivered message is updated.
         /// </summary>
-        public Action OnLastDeliveredAtUpdated {
+        public Action<LCIMConversation> OnLastDeliveredAtUpdated {
             get; set;
         }
 
         /// <summary>
-        /// Occurs when the last delivered message is updated.
+        /// Occurs when the last read message is updated.
         /// </summary>
-        public Action OnLastReadAtUpdated {
+        public Action<LCIMConversation> OnLastReadAtUpdated {
             get; set;
         }