feat: store theme in session

Author: javier-godoy

pom.xml

@@ -90,6 +90,13 @@
 		<scope>provided</scope>
 	</dependency>
 
+	<dependency>
+		<groupId>jakarta.servlet</groupId>
+		<artifactId>jakarta.servlet-api</artifactId>
+		<version>6.0.0</version>
+		<scope>provided</scope>
+	</dependency>
+		
     <dependency>
         <groupId>com.flowingcode.vaadin.addons</groupId>
         <artifactId>enhanced-tabs-addon</artifactId>

src/main/java/com/flowingcode/vaadin/addons/demo/TabbedDemo.java

@@ -39,6 +39,7 @@
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
 import com.vaadin.flow.router.RouterLayout;
+import com.vaadin.flow.server.VaadinSession;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
@@ -227,6 +228,8 @@ public void showRouterLayoutContent(HasElement content) {
 
     updateFooterButtonsVisibility();
     getElement().insertChild(1, content.getElement());
+
+    applyTheme(getElement(), getThemeName());
   }
 
   private Optional<SourceCodeTab> createSourceCodeTab(Class<?> annotatedClass, DemoSource annotation) {
@@ -338,8 +341,22 @@ public void setOrientation(Orientation orientation) {
     orientationCB.setValue(Orientation.HORIZONTAL.equals(orientation));
   }
 
+  private static final String THEME_NAME = TabbedDemo.class.getName() + "#THEME_NAME";
+
+  public static String getThemeName() {
+    return (String) Optional.ofNullable(VaadinSession.getCurrent().getAttribute(THEME_NAME))
+        .orElse("");
+  }
+
+  @Deprecated
   public static void applyTheme(Element element, boolean useDarkTheme) {
     String theme = useDarkTheme ? "dark" : "";
+    applyTheme(element, theme);
+  }
+
+  public static void applyTheme(Element element, String theme) {
+    VaadinSession.getCurrent().setAttribute(THEME_NAME, theme);
+
     element.executeJs("document.documentElement.setAttribute('theme', $0);", theme);
 
     Component c = element.getComponent().get();