1 files changed, 111 insertions, 0 deletions
diff --git a/ModAS.Server/Services/RoomContextService.cs b/ModAS.Server/Services/RoomContextService.cs
new file mode 100644
index 0000000..b3673c1
--- /dev/null
+++ b/ModAS.Server/Services/RoomContextService.cs
@@ -0,0 +1,111 @@
+using ArcaneLibs.Extensions;
+using Elastic.Apm;
+using Elastic.Apm.Api;
+using LibMatrix;
+using LibMatrix.EventTypes.Spec.State;
+using LibMatrix.RoomTypes;
+using MxApiExtensions.Services;
+
+namespace ModAS.Server.Services;
+
+public class RoomContextService(UserProviderService userProvider, ModASConfiguration config) {
+    public Dictionary<string, RoomContext> RoomContexts { get; } = new();
+    public Dictionary<string, List<string>> LocalUsersByRoom { get; private set; } = new();
+
+    public async Task<RoomContext?> GetRoomContext(GenericRoom room) {
+        if (RoomContexts.TryGetValue(room.RoomId, out var roomContext) && !roomContext.NeedsUpdate) return roomContext;
+
+        var newRoomContext = await FetchRoomContext(room.RoomId);
+        if (newRoomContext is not null) RoomContexts[room.RoomId] = newRoomContext;
+        return roomContext;
+    }
+
+    public async Task<RoomContext?> GetRoomContext(string roomId) {
+        if (RoomContexts.TryGetValue(roomId, out var roomContext) && !roomContext.NeedsUpdate) return roomContext;
+
+        var newRoomContext = await FetchRoomContext(roomId);
+        if (newRoomContext is not null) RoomContexts[roomId] = newRoomContext;
+        return roomContext;
+    }
+
+    public async Task<RoomContext?> FetchRoomContext(string roomId) {
+        var span = currentTransaction.StartSpan($"FetchRoomContext - {roomId}", ApiConstants.TypeApp);
+        if (!LocalUsersByRoom.ContainsKey(roomId))
+            await UpdateLocalUserRoomLists();
+        if (!LocalUsersByRoom.TryGetValue(roomId, out var localUsers)) return null;
+        if (localUsers.Count == 0) return null;
+
+        var roomContext = new RoomContext {
+            RoomId = roomId
+        };
+
+        var room = (await userProvider.GetImpersonatedHomeserver(localUsers.First())).GetRoom(roomId);
+        var roomMembers = await room.GetMembersListAsync(false);
+        
+        roomContext.UserCountByMembership = roomMembers.GroupBy(x => (x.TypedContent as RoomMemberEventContent)?.Membership)
+            .ToDictionary(x => x.Key, x => x.Count());
+        roomContext.LocalUsers = roomMembers.Select(x => x.StateKey).Where(x => x.EndsWith(':' + config.ServerName)).ToList();
+        roomContext.CurrentLocalUsers = roomMembers.Where(x => x.StateKey.EndsWith(':' + config.ServerName) && (x.TypedContent as RoomMemberEventContent)?.Membership == "join")
+            .Select(x => x.StateKey).ToList();
+
+        var powerLevels = await room.GetPowerLevelsAsync();
+        roomContext.LocalUsersByStatePermission = powerLevels?.Events?
+            .Select(@event => (@event.Key, roomContext.CurrentLocalUsers.Where(clu => powerLevels.UserHasStatePermission(clu, @event.Key))))
+            .Where(x => x.Item2.Any())
+            .ToDictionary(x => x.Key, x => x.Item2.ToList());
+
+        roomContext.LastUpdate = DateTime.Now;
+        
+        span.End();
+        return roomContext;
+    }
+
+    private async Task UpdateLocalUserRoomLists() {
+        var span = currentTransaction.StartSpan("UpdateLocalUserRoomLists", ApiConstants.TypeApp);
+        var newLocalUsersByRoom = new Dictionary<string, List<string>>();
+        var users = await userProvider.GetValidUsers();
+        var getRoomsSpan = currentTransaction.StartSpan("GetRooms", ApiConstants.TypeApp);
+        var userRoomLists = users.Values.Select(ahs => (ahs, ahs.GetJoinedRooms())).ToList();
+        await Task.WhenAll(userRoomLists.Select(x => x.Item2));
+        getRoomsSpan.End();
+        foreach (var (ahs, rooms) in userRoomLists) {
+            foreach (var room in rooms.Result) {
+                newLocalUsersByRoom.TryAdd(room.RoomId, new List<string>());
+                newLocalUsersByRoom[room.RoomId].Add(ahs.UserId);
+            }
+        }
+        span.End();
+        LocalUsersByRoom = newLocalUsersByRoom;
+    }
+
+    public class RoomContext {
+        public string RoomId { get; set; }
+        public List<string> LocalUsers { get; set; }
+        public List<string> CurrentLocalUsers { get; set; }
+        public Dictionary<string, int> UserCountByMembership { get; set; }
+        public Dictionary<string, List<string>> LocalUsersByStatePermission { get; set; }
+
+        public DateTime LastUpdate { get; set; }
+        public bool NeedsUpdate => DateTime.Now - LastUpdate > TimeSpan.FromMinutes(5);
+    }
+
+    public async Task<GenericRoom?> GetRoomReferenceById(string roomId) {
+        var roomContext = await GetRoomContext(roomId);
+        var localUsers = roomContext.LocalUsers.Select(userProvider.GetImpersonatedHomeserver).ToAsyncEnumerable();
+        await foreach (var localUser in localUsers) {
+            var room = localUser.GetRoom(roomId);
+            try {
+                if (await room.GetCreateEventAsync() is not null)
+                    return room;
+            }
+            catch (MatrixException e) {
+                if (e is { ErrorCode: "M_UNAUTHORIZED" }) continue;
+                throw;
+            }
+        }
+
+        return null;
+    }
+    
+    private static ITransaction currentTransaction => Agent.Tracer.CurrentTransaction;
+}
\ No newline at end of file