Add timer to send alerts

Environment/Service/DeviceCheckService.cs

@@ -0,0 +1,77 @@
+using ChrisKaczor.HomeMonitor.Environment.Service.Data;
+using RestSharp;
+
+namespace ChrisKaczor.HomeMonitor.Environment.Service;
+
+public class DeviceCheckService(Database _database, IConfiguration _configuration) : IHostedService
+{
+    private Timer? _timer;
+    private TimeSpan _warningInterval;
+
+    private readonly string _botToken = _configuration["Telegram:BotToken"]!;
+    private readonly string _chatId = _configuration["Telegram:ChatId"]!;
+    private readonly RestClient _restClient = new();
+
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        WriteLog("DeviceCheckService started");
+
+        _warningInterval = TimeSpan.Parse(_configuration["Environment:DeviceWarningInterval"]!);
+
+        var checkInterval = TimeSpan.Parse(_configuration["Environment:DeviceCheckInterval"]!);
+
+        _timer = new Timer((state) => DoWork().Wait(), null, TimeSpan.Zero, checkInterval);
+
+        return Task.CompletedTask;
+    }
+
+    private async Task DoWork()
+    {
+        WriteLog("Checking devices started");
+
+        var devices = await _database.GetDevicesAsync();
+
+        foreach (var device in devices)
+        {
+            WriteLog($"Checking device: {device.Name}");
+
+            var message = string.Empty;
+
+            WriteLog($"Device {device.Name} last updated: {(device.LastUpdated == null ? "never" : device.LastUpdated.ToString())}");
+
+            if (device.LastUpdated == null)
+            {
+                message = $"Device has never reported: {device.Name}";
+            }
+            else if (DateTime.UtcNow - device.LastUpdated > _warningInterval)
+            {
+                message = $"Device has not reported recently: {device.Name}";
+            }
+
+            if (message.Length > 0)
+            {
+                var encodedMessage = Uri.EscapeDataString(message);
+
+                var restRequest = new RestRequest($"https://api.telegram.org/bot{_botToken}/sendMessage?chat_id={_chatId}&text={encodedMessage}");
+
+                await _restClient.GetAsync(restRequest);
+            }
+        }
+
+        WriteLog("Checking devices finished");
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken)
+    {
+        WriteLog("DeviceCheckService stopped");
+
+        _timer?.Change(Timeout.Infinite, 0);
+
+        return Task.CompletedTask;
+    }
+
+    private static void WriteLog(string message)
+    {
+        Console.WriteLine(message);
+    }
+}