add support for dance alert

src/Core/RoomWithAlert.cs

@@ -0,0 +1,48 @@
+using sodoffmmo.Data;
+using System.Timers;
+
+namespace sodoffmmo.Core;
+class RoomWithAlert : Room {
+    private int alertId;
+    private System.Timers.Timer? timer = null;
+    private Random random = new Random();
+    
+    private int minTime;
+    private int maxTime;
+    private int songs;
+    
+    public RoomWithAlert(string name, int minTime = 30, int maxTime = 240, int songs = 16) : base (name) {
+        alertId = -1;
+        
+        this.minTime = minTime;
+        this.maxTime = maxTime;
+        this.songs = songs;
+        
+        SetTimer();
+    }
+    
+    private void StartAlert(Object? source, ElapsedEventArgs e) {
+        int songId = random.Next(0, songs);
+        RoomVariables = new();
+        RoomVariables.Add(NetworkArray.VlElement("RA_S", ++alertId, isPersistent: true));
+        RoomVariables.Add(NetworkArray.VlElement("RA_A", "3", isPersistent: true));
+        RoomVariables.Add(NetworkArray.VlElement("RA_L", 20.0, isPersistent: true));
+        RoomVariables.Add(NetworkArray.VlElement("RA_SO", (double)songId, isPersistent: true));
+        NetworkPacket packet = Utils.VlNetworkPacket(RoomVariables, Id);
+        Send(packet);
+        SetTimer();
+    }
+    
+    private void SetTimer() {
+        if (timer != null) {
+            timer.Stop();
+            timer.Close();
+        }
+        timer = new System.Timers.Timer(
+            random.Next(minTime * 1000, maxTime * 1000)
+        );
+        timer.AutoReset = false;
+        timer.Enabled = true;
+        timer.Elapsed += StartAlert;
+    }
+}

src/Server.cs

@@ -28,6 +28,7 @@ public class Server {
         if (IPv6AndIPv4)
             listener.SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only, 0);
         listener.Bind(new IPEndPoint(ipAddress, port));
+        new RoomWithAlert("LoungeInt"); // FIXME use config for this
         await Listen(listener);
     }