Removing CssThemeManager dependency on ServerController

Using newly created BaseAsyncService to listen for database changes of theme setting

BTCPayServer/Controllers/ServerController.cs

@@ -25,17 +25,14 @@ namespace BTCPayServer.Controllers
         private UserManager<ApplicationUser> _UserManager;
         SettingsRepository _SettingsRepository;
         private IRateProviderFactory _RateProviderFactory;
-        private CssThemeManager _CssThemeManager;
 
         public ServerController(UserManager<ApplicationUser> userManager,
             IRateProviderFactory rateProviderFactory,
-            SettingsRepository settingsRepository, 
+            SettingsRepository settingsRepository)
-	    CssThemeManager cssThemeManager)
         {
             _UserManager = userManager;
             _SettingsRepository = settingsRepository;
             _RateProviderFactory = rateProviderFactory;
-            _CssThemeManager = cssThemeManager;
         }
 
         [Route("server/rates")]
@@ -234,9 +231,6 @@ namespace BTCPayServer.Controllers
         public async Task<IActionResult> Theme(ThemeSettings settings)
         {
             await _SettingsRepository.UpdateSetting(settings);
-            // TODO: remove controller/class-level property and have only reference to 
-            // CssThemeManager here in this method
-            _CssThemeManager.Update(settings);
             TempData["StatusMessage"] = "Theme settings updated successfully";
             return View(settings);
         }

BTCPayServer/HostedServices/CssThemeManager.cs

@@ -16,47 +16,59 @@ namespace BTCPayServer.HostedServices
 {
     public class CssThemeManager
     {
-        public CssThemeManager(SettingsRepository settingsRepository)
-        {
-            Update(settingsRepository);
-        }
-
-        private async void Update(SettingsRepository settingsRepository)
-        {
-            var data = (await settingsRepository.GetSettingAsync<ThemeSettings>()) ?? new ThemeSettings();
-            Update(data);
-        }
-
         public void Update(ThemeSettings data)
         {
-            UpdateBootstrap(data.BootstrapCssUri);
+            if (String.IsNullOrWhiteSpace(data.BootstrapCssUri))
-            UpdateCreativeStart(data.CreativeStartCssUri);
+                _bootstrapUri = "/vendor/bootstrap4/css/bootstrap.css?v=" + DateTime.Now.Ticks;
+            else
+                _bootstrapUri = data.BootstrapCssUri;
+
+
+            if (String.IsNullOrWhiteSpace(data.CreativeStartCssUri))
+                _creativeStartUri = "/vendor/bootstrap4-creativestart/creative.css?v=" + DateTime.Now.Ticks;
+            else
+                _creativeStartUri = data.CreativeStartCssUri;
         }
 
-        private string _bootstrapUri = "/vendor/bootstrap4/css/bootstrap.css?v=" + DateTime.Now.Ticks;
+        private string _bootstrapUri;
         public string BootstrapUri
         {
             get { return _bootstrapUri; }
         }
-        public void UpdateBootstrap(string newUri)
-        {
-            if (String.IsNullOrWhiteSpace(newUri))
-                _bootstrapUri = "/vendor/bootstrap4/css/bootstrap.css?v="+ DateTime.Now.Ticks;
-            else
-                _bootstrapUri = newUri;
-        }
 
-        private string _creativeStartUri = "/vendor/bootstrap4-creativestart/creative.css?v=" + DateTime.Now.Ticks;
+        private string _creativeStartUri;
         public string CreativeStartUri
         {
             get { return _creativeStartUri; }
         }
-        public void UpdateCreativeStart(string newUri)
+    }
+
+    public class CssThemeManagerHostedService : BaseAsyncService
+    {
+        private SettingsRepository _SettingsRepository;
+        private CssThemeManager _CssThemeManager;
+
+        public CssThemeManagerHostedService(SettingsRepository settingsRepository, CssThemeManager cssThemeManager)
         {
-            if (String.IsNullOrWhiteSpace(newUri))
+            _SettingsRepository = settingsRepository;
-                _creativeStartUri = "/vendor/bootstrap4-creativestart/creative.css?v=" + DateTime.Now.Ticks;
+            _CssThemeManager = cssThemeManager;
-            else
+        }
-                _creativeStartUri = newUri;
+
+        internal override Task[] initializeTasks()
+        {
+            return new[]
+            {
+                createLoopTask(ListenForThemeChanges)
+            };
+        }
+
+        async Task ListenForThemeChanges()
+        {
+            await new SynchronizationContextRemover();
+            var data = (await _SettingsRepository.GetSettingAsync<ThemeSettings>()) ?? new ThemeSettings();
+            _CssThemeManager.Update(data);
+
+            await _SettingsRepository.WaitSettingsChanged<ThemeSettings>(_Cts.Token);
         }
     }
 }

BTCPayServer/Hosting/BTCPayServerServices.cs

@@ -138,7 +138,6 @@ namespace BTCPayServer.Hosting
 
             services.TryAddSingleton<LanguageService>();
             services.TryAddSingleton<NBXplorerDashboard>();
-            services.TryAddSingleton<CssThemeManager>();
             services.TryAddSingleton<StoreRepository>();
             services.TryAddSingleton<BTCPayWalletProvider>();
             services.TryAddSingleton<CurrencyNameTable>();
@@ -148,6 +147,9 @@ namespace BTCPayServer.Hosting
                 BlockTarget = 20
             });
 
+            services.AddSingleton<CssThemeManager>();
+            services.AddSingleton<IHostedService, CssThemeManagerHostedService>();
+
             services.AddSingleton<Payments.IPaymentMethodHandler<DerivationStrategy>, Payments.Bitcoin.BitcoinLikePaymentHandler>();
             services.AddSingleton<IHostedService, Payments.Bitcoin.NBXplorerListener>();