From e9017498a0bd87e2a5ae457c00f9ddee35809c29 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sat, 15 May 2021 16:01:21 +0800
Subject: feat: Timeline post change notification with signalr.

---
 BackEnd/Timeline/SignalRHub/TimelineHub.cs | 58 ++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 BackEnd/Timeline/SignalRHub/TimelineHub.cs

(limited to 'BackEnd/Timeline/SignalRHub/TimelineHub.cs')

diff --git a/BackEnd/Timeline/SignalRHub/TimelineHub.cs b/BackEnd/Timeline/SignalRHub/TimelineHub.cs
new file mode 100644
index 00000000..2ad7bd66
--- /dev/null
+++ b/BackEnd/Timeline/SignalRHub/TimelineHub.cs
@@ -0,0 +1,58 @@
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Threading.Tasks;
+using Timeline.Auth;
+using Timeline.Services;
+using Timeline.Services.Timeline;
+using Timeline.Services.User;
+
+namespace Timeline.SignalRHub
+{
+    public class TimelineHub : Hub<ITimelineClient>
+    {
+        private readonly ILogger<TimelineHub> _logger;
+        private readonly ITimelineService _timelineService;
+
+        public TimelineHub(ILogger<TimelineHub> logger, ITimelineService timelineService)
+        {
+            _logger = logger;
+            _timelineService = timelineService;
+        }
+
+        public static string GenerateTimelinePostChangeListeningGroupName(string timelineName)
+        {
+            return $"timeline-post-change-{timelineName}";
+        }
+
+        public async Task SubscribeTimelinePostChange(string timelineName)
+        {
+            try
+            {
+                var timelineId = await _timelineService.GetTimelineIdByNameAsync(timelineName);
+                var user = Context.User;
+                if (!user.HasPermission(UserPermission.AllTimelineManagement) && !await _timelineService.HasReadPermissionAsync(timelineId, user.GetOptionalUserId()))
+                    throw new HubException("Forbidden.");
+
+                var group = GenerateTimelinePostChangeListeningGroupName(timelineName);
+                await Groups.AddToGroupAsync(Context.ConnectionId, group);
+                _logger.LogInformation("Add connection {0} to group {1}", Context.ConnectionId, group);
+            }
+            catch (ArgumentException)
+            {
+                throw new HubException("Timeline name is illegal.");
+            }
+            catch (EntityNotExistException)
+            {
+                throw new HubException("Timeline not exist.");
+            }
+        }
+
+        public async Task UnsubscribeTimelinePostChange(string timelineName)
+        {
+            var group = GenerateTimelinePostChangeListeningGroupName(timelineName);
+            await Groups.RemoveFromGroupAsync(Context.ConnectionId, group);
+            _logger.LogInformation("Remove connection {0} from group {1}", Context.ConnectionId, group);
+        }
+    }
+}
-- 
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