Added RaidTemplates and TimerService to create weekly raids

Lieb/Data/TimerService.cs

@@ -0,0 +1,60 @@
+using Lieb.Models.GuildWars2.Raid;
+
+namespace Lieb.Data
+{
+    public class TimerService : IHostedService, IDisposable 
+    {
+        private Timer _timer = null!;
+        private IServiceProvider _services;
+
+        public TimerService(IServiceProvider services)
+        {
+            _services = services;
+        }
+
+        public Task StartAsync(CancellationToken stoppingToken)
+        {
+            _timer = new Timer(CheckRaids, null, TimeSpan.Zero,
+                TimeSpan.FromMinutes(1));
+
+            return Task.CompletedTask;
+        }
+
+        private void CheckRaids(object? state)
+        {
+            using (var scope = _services.CreateScope())
+            {
+                var raidTemplateService =
+                    scope.ServiceProvider
+                        .GetRequiredService<RaidTemplateService>();
+
+                foreach(RaidTemplate template in raidTemplateService.GetTemplates())
+                {
+                    TimeZoneInfo timeZone = TimeZoneInfo.FindSystemTimeZoneById(template.TimeZone);
+                    DateTime UTCStartTime = TimeZoneInfo.ConvertTimeToUtc(template.StartTime, timeZone);
+                    if(UTCStartTime.AddDays(-template.CreateDaysBefore).AddHours(1) < DateTime.UtcNow)
+                    {
+                        raidTemplateService.CreateNewRaid(template.RaidTemplateId).Wait();
+                    }
+                }
+
+                var raidService =
+                    scope.ServiceProvider
+                        .GetRequiredService<RaidService>();
+                raidService.SendReminders();
+            }
+        }
+
+        public Task StopAsync(CancellationToken stoppingToken)
+        {
+            _timer?.Change(Timeout.Infinite, 0);
+
+            return Task.CompletedTask;
+        }
+
+        public void Dispose()
+        {
+            _timer?.Dispose();
+        }
+    }
+}