feat: add support for last time connected in the status command

src/CasaBot/CasaBotApp/Controllers/BotController.cs

@@ -114,7 +114,21 @@ public class BotController : IController
     [BotCommand("/status", "Get the status of the alarm")]
     public async Task Status(TextMessage msg, BotCommand ctx)
     {
-        await ctx.Responder(msg, _controlServer.IsConnected() ? "Alarm is connected 🟢" : "Alarm is not connected 🔴");
+        
+        await ctx.Responder(msg, _controlServer.IsConnected() ? 
+            $"Alarm is connected 🟢\nLast Contact: {FormatTimeSpan(_controlServer.GetLastContactTime())} ago" : 
+            $"Alarm is not connected 🔴\nLast Contact: {FormatTimeSpan(_controlServer.GetLastContactTime())} ago");
+    }
+
+    private string FormatTimeSpan(TimeSpan? timeSpan)
+    {
+        //return a string with the format HH:mm:ss for HH > 0 and mm:ss for HH = 0
+        if(timeSpan == null || timeSpan == TimeSpan.Zero)
+            return "Never";
+        var ts = timeSpan.Value;
+        return ts.Hours > 0 ?
+            $"{ts.Hours:D2}:{ts.Minutes:D2}:{ts.Seconds:D2}" : 
+            $"{ts.Minutes:D2}:{ts.Seconds:D2}";
     }
 
     private void HandleReply()

src/CasaBot/ControlServer/ControlServer.cs

@@ -14,7 +14,7 @@ public class ControlServer : IControlServer
     private Func<SensorEvent, Task>? _onEventRecived;
     private bool _disarmRequestPending;
     private DateTime _disarmRequestTime;
-    private DateTime _lastContactTime;
+    private DateTime? _lastContactTime;
 
     public ControlServer(ILogger<ControlServer> logger, IOptions<ControlServerOptions> options)
     {
@@ -201,7 +201,17 @@ public class ControlServer : IControlServer
     public bool IsConnected()
     {
         //Check if the last contact time was less than 5 minutes ago
-        return (DateTime.Now - _lastContactTime).TotalMinutes < 1;
+        if(_lastContactTime is null)
+            return false;
+        return (DateTime.Now - _lastContactTime.Value).TotalMinutes < 1;
     }
+    //function to return how long ago was the last contact as timespan
+    public TimeSpan? GetLastContactTime()
+    {
+        if(_lastContactTime is null)
+            return null;
+        return DateTime.Now - _lastContactTime;
+    }
+    
 
 }

src/CasaBot/ControlServer/IControlServer.cs

@@ -8,4 +8,5 @@ public interface IControlServer : IHostedService
     public void AuthorizeEvent(long eventId);
     public void RequestDisarm();
     public bool IsConnected();
+    public TimeSpan? GetLastContactTime();
 }