Start to display banner

lib/helpers/server_config_helper.dart

@@ -17,6 +17,7 @@ class ServerConfigurationHelper {
         (await APIRequest.withoutLogin("server/config").execWithThrow())
             .getObject();
 
+    final banner = response["banner"];
     final pushNotificationsPolicy = response["push_notifications"];
     final passwordPolicy = response["password_policy"];
     final dataConservationPolicy = response["data_conservation_policy"];
@@ -31,6 +32,15 @@ class ServerConfigurationHelper {
       contactEmail: response["contact_email"],
       playStoreURL: response["play_store_url"],
       androidDirectDownloadURL: response["android_direct_download_url"],
+      banner: banner == null
+          ? null
+          : Banner(
+              enabled: banner["enabled"],
+              expire: banner["expire"],
+              nature: BannerNatureExt.fromStr(banner["nature"]),
+              message: Map<String, dynamic>.from(banner["message"])
+                  .map((key, value) => MapEntry(key, value.toString())),
+              link: banner["link"]),
       notificationsPolicy: NotificationsPolicy(
         hasFirebase: pushNotificationsPolicy["has_firebase"],
         hasIndependent: pushNotificationsPolicy["has_independent"],
@@ -98,3 +108,5 @@ class ServerConfigurationHelper {
 
 /// Shortcut for server configuration
 ServerConfig get srvConfig => ServerConfigurationHelper.config;
+
+bool get showBanner => srvConfig.banner != null && srvConfig.banner.visible;