Basic rtl (#997)

* RTL for vanilla bootstrap is added

* RTL support for bootswatch was added

(cherry picked from commit c1fe914)

bootstrap-core/src/main/java/de/agilecoders/wicket/core/markup/html/bootstrap/html/HtmlTag.java

@@ -2,11 +2,13 @@
 
 import java.util.Locale;
 
+import org.apache.wicket.Session;
 import org.apache.wicket.markup.ComponentTag;
 import org.apache.wicket.markup.head.HeaderItem;
 import org.apache.wicket.markup.head.IHeaderResponse;
 import org.apache.wicket.markup.head.JavaScriptHeaderItem;
 import org.apache.wicket.markup.html.TransparentWebMarkupContainer;
+import org.apache.wicket.protocol.http.WebSession;
 
 import de.agilecoders.wicket.core.Bootstrap;
 import de.agilecoders.wicket.core.markup.html.references.ModernizrJavaScriptReference;
@@ -46,6 +48,7 @@
  */
 public class HtmlTag extends TransparentWebMarkupContainer {
     private static final long serialVersionUID = 1L;
+    private final boolean isRtl;
     private final boolean useModernizr;
     private final Locale locale;
 
@@ -61,6 +64,7 @@ public HtmlTag(final String markupId, final Locale locale, final boolean useMode
 
         this.locale = locale;
         this.useModernizr = useModernizr;
+        this.isRtl = locale == null ? false : Session.isRtlLanguage(locale);
     }
 
     /**
@@ -114,6 +118,9 @@ protected void onComponentTag(final ComponentTag tag) {
         if (locale != null) {
             tag.put("lang", toAttributeValue(locale));
         }
+        if (isRtl) {
+            tag.put("dir", "rtl");
+        }
 
         final CssClassNames.Builder cssClassNames = CssClassNames.newBuilder();
         if (useModernizr) {

bootstrap-core/src/main/java/de/agilecoders/wicket/core/markup/html/themes/bootstrap/BootstrapCssRtlReference.java

@@ -0,0 +1,50 @@
+package de.agilecoders.wicket.core.markup.html.themes.bootstrap;
+
+import de.agilecoders.wicket.webjars.request.resource.WebjarsCssResourceReference;
+
+/**
+ * #### Description
+ *
+ * The RTL (right-to-left) bootstrap css. To update the bootstrap version add the following dependency to
+ * your maven `dependencyManagement` section:
+ *
+ * ```xml
+ * <dependency>
+ *     <groupId>org.webjars</groupId>
+ *     <artifactId>bootstrap</artifactId>
+ *     <version>your-bootstrap-version</version>
+ * </dependency>
+ * ```
+ *
+ * The css resource will be loaded by wicket-webjars.
+ *
+ * @author Michael Haitz <michael.haitz@agilecoders.de>
+ */
+public class BootstrapCssRtlReference extends WebjarsCssResourceReference {
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * Singleton instance of this reference
+     */
+    private static final class Holder {
+        private static final BootstrapCssRtlReference INSTANCE = new BootstrapCssRtlReference();
+    }
+
+    /**
+     * Normally you should not use this method, but use
+     * {@link de.agilecoders.wicket.core.settings.IBootstrapSettings#getCssResourceReference()} ()} to prevent version conflicts.
+     *
+     * @return the single instance of the resource reference
+     */
+    public static BootstrapCssRtlReference instance() {
+        return Holder.INSTANCE;
+    }
+
+    /**
+     * Private constructor.
+     */
+    private BootstrapCssRtlReference() {
+        super("/bootstrap/current/css/bootstrap.rtl.css");
+    }
+
+}

bootstrap-core/src/main/java/de/agilecoders/wicket/core/settings/BootstrapSettings.java

@@ -1,12 +1,14 @@
 package de.agilecoders.wicket.core.settings;
 
+import org.apache.wicket.protocol.http.WebSession;
 import org.apache.wicket.request.Url;
 import org.apache.wicket.request.resource.ResourceReference;
 import org.apache.wicket.request.resource.UrlResourceReference;
 
 import de.agilecoders.wicket.core.markup.html.references.BootstrapJavaScriptReference;
 import de.agilecoders.wicket.core.markup.html.references.ModernizrJavaScriptReference;
 import de.agilecoders.wicket.core.markup.html.themes.bootstrap.BootstrapCssReference;
+import de.agilecoders.wicket.core.markup.html.themes.bootstrap.BootstrapCssRtlReference;
 
 /**
  * #### Description
@@ -22,11 +24,13 @@ private static final class Holder {
         private static ResourceReference bootstrapJavaScriptReference = BootstrapJavaScriptReference.instance();
         private static ResourceReference modernizrJavaScriptReference = ModernizrJavaScriptReference.instance();
         private static ResourceReference bootstrapCssReference = BootstrapCssReference.instance();
+        private static ResourceReference bootstrapCssRtlReference = BootstrapCssRtlReference.instance();
     }
 
     private ResourceReference bootstrapJavaScriptReference = null;
     private ResourceReference modernizrJavaScriptReference = null;
     private ResourceReference bootstrapCssReference = null;
+    private ResourceReference bootstrapCssRtlReference = null;
 
     private ThemeProvider themeProvider;
     private ActiveThemeProvider activeThemeProvider;
@@ -88,14 +92,19 @@ public boolean autoAppendResources() {
     public ResourceReference getCssResourceReference() {
         ResourceReference ref;
 
+        final boolean isRtl = WebSession.exists() && WebSession.get().isRtlLocale();
+
         if (useCdnResources()) {
-            String cdnUrl = String.format(CSS_CDN_PATTERN, getVersion());
+            String cdnUrl = String.format(isRtl ? CSS_RTL_CDN_PATTERN : CSS_CDN_PATTERN, getVersion());
             ref = new UrlResourceReference(Url.parse(cdnUrl));
         } else {
-            ref = bootstrapCssReference;
+            ref = isRtl ? bootstrapCssRtlReference : bootstrapCssReference;
+        }
+        if (ref == null) {
+            ref = isRtl ? Holder.bootstrapCssRtlReference : Holder.bootstrapCssReference;
         }
 
-        return ref != null ? ref : Holder.bootstrapCssReference;
+        return ref;
     }
 
     @Override
@@ -160,6 +169,12 @@ public IBootstrapSettings setCssResourceReference(ResourceReference reference) {
         return this;
     }
 
+    @Override
+    public IBootstrapSettings setCssRtlResourceReference(ResourceReference reference) {
+        bootstrapCssRtlReference = reference;
+        return this;
+    }
+
     @Override
     public BootstrapSettings setJsResourceReference(final ResourceReference bootstrapJavaScriptReference) {
         this.bootstrapJavaScriptReference = bootstrapJavaScriptReference;

bootstrap-core/src/main/java/de/agilecoders/wicket/core/settings/IBootstrapSettings.java

@@ -36,6 +36,11 @@ public interface IBootstrapSettings {
      */
     String CSS_CDN_PATTERN = "//stackpath.bootstrapcdn.com/bootstrap/%s/css/bootstrap.min.css";
 
+    /**
+     * The url to the right-to-left css resource at a CDN network
+     */
+    String CSS_RTL_CDN_PATTERN = "//stackpath.bootstrapcdn.com/bootstrap/%s/css/bootstrap.rtl.min.css";
+
     /**
      * @param version The version of Bootstrap. CDN resources use it to construct their urls
      * @return same instance for chaining
@@ -90,6 +95,13 @@ public interface IBootstrapSettings {
      */
     IBootstrapSettings setCssResourceReference(ResourceReference reference);
 
+    /**
+     * @param reference a reference to the RTL (right-to-left) bootstrap css library.
+     *                  Defaults to the embedded bootstrap.rtl.css
+     * @return same instance for chaining
+     */
+    IBootstrapSettings setCssRtlResourceReference(ResourceReference reference);
+
     /**
      * @param reference a reference to the base bootstrap JavaScript library.
      *                  Defaults to the embedded bootstrap.js

bootstrap-core/src/main/java/de/agilecoders/wicket/core/settings/NoopThemeProvider.java

@@ -1,6 +1,5 @@
 package de.agilecoders.wicket.core.settings;
 
-import java.util.Collections;
 import java.util.List;
 
 import org.apache.wicket.markup.head.CssHeaderItem;
@@ -44,7 +43,7 @@ public String name() {
 
         @Override
         public List<HeaderItem> getDependencies() {
-            return Collections.emptyList();
+            return List.of();
         }
 
         @Override
@@ -54,7 +53,7 @@ public void renderHead(IHeaderResponse response) {
 
         @Override
         public Iterable<String> getCdnUrls() {
-            return Collections.emptyList();
+            return List.of();
         }
     }
 }

bootstrap-core/src/main/java/de/agilecoders/wicket/core/settings/Theme.java

@@ -13,7 +13,6 @@
 import org.apache.wicket.request.resource.UrlResourceReference;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -97,7 +96,7 @@ private boolean useCdnResources() {
 
     @Override
     public Iterable<String> getCdnUrls() {
-        return Collections.emptyList();
+        return List.of();
     }
 
     private void renderPackageReferences(IHeaderResponse response) {

bootstrap-samples/src/main/java/de/agilecoders/wicket/samples/pages/BasePage.java

@@ -14,6 +14,7 @@
 import org.apache.wicket.markup.html.WebMarkupContainer;
 import org.apache.wicket.markup.html.link.AbstractLink;
 import org.apache.wicket.model.Model;
+import org.apache.wicket.protocol.http.WebSession;
 import org.apache.wicket.request.mapper.parameter.PageParameters;
 import org.apache.wicket.util.string.StringValue;
 
@@ -62,7 +63,7 @@ abstract class BasePage extends GenericWebPage<Void> {
     public BasePage(final PageParameters parameters) {
         super(parameters);
 
-        add(new HtmlTag("html"));
+        add(new HtmlTag("html", WebSession.get().getLocale()));
         MobileViewportMetaTag mvt = new MobileViewportMetaTag("viewport");
         mvt.setWidth("device-width");
         mvt.setInitialScale("1");