[Issue #2526] Lazy evaluate navigation sub-items on demand

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/models/v1/BreadcrumbImpl.java

@@ -41,8 +41,8 @@
 import com.day.cq.wcm.api.designer.Style;
 
 @Model(adaptables = SlingHttpServletRequest.class,
-       adapters = {Breadcrumb.class, ComponentExporter.class},
-       resourceType = {BreadcrumbImpl.RESOURCE_TYPE_V1, BreadcrumbImpl.RESOURCE_TYPE_V2})
+    adapters = {Breadcrumb.class, ComponentExporter.class},
+    resourceType = {BreadcrumbImpl.RESOURCE_TYPE_V1, BreadcrumbImpl.RESOURCE_TYPE_V2})
 @Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME, extensions = ExporterConstants.SLING_MODEL_EXTENSION)
 public class BreadcrumbImpl extends AbstractComponentImpl implements Breadcrumb {
 
@@ -62,9 +62,6 @@ public class BreadcrumbImpl extends AbstractComponentImpl implements Breadcrumb
     @ScriptVariable
     private Page currentPage;
 
-    @Self
-    private SlingHttpServletRequest request;
-
     @Self
     protected LinkManager linkManager;
 
@@ -88,12 +85,6 @@ public Collection<NavigationItem> getItems() {
         return Collections.unmodifiableList(items);
     }
 
-    @NotNull
-    @Override
-    public String getExportedType() {
-        return request.getResource().getResourceType();
-    }
-
     private List<NavigationItem> createItems() {
         List<NavigationItem> items = new ArrayList<>();
         int currentLevel = currentPage.getDepth();
@@ -105,8 +96,7 @@ private List<NavigationItem> createItems() {
                     break;
                 }
                 if (checkIfNotHidden(page)) {
-                    NavigationItem navigationItem = newBreadcrumbItem(page, isActivePage, linkManager, currentLevel,
-                            Collections.emptyList(), getId(), component);
+                    NavigationItem navigationItem = newBreadcrumbItem(page, isActivePage, linkManager, currentLevel, getId(), component);
                     items.add(navigationItem);
                 }
             }
@@ -115,11 +105,37 @@ private List<NavigationItem> createItems() {
         return items;
     }
 
-    protected NavigationItem newBreadcrumbItem(Page page, boolean active, @NotNull LinkManager linkManager, int level, List<NavigationItem> children, String parentId, Component component) {
-        return new BreadcrumbItemImpl(page, active, linkManager, level, children, parentId, component);
+    /**
+     * Create a Breadcrumb Item.
+     *
+     * @param page        The page for which to create a breadcrumb item.
+     * @param active      Flag indicating if the breadcrumb item is active.
+     * @param linkManager Link manager service.
+     * @param level       Depth level of the navigation item.
+     * @param parentId    ID of the parent navigation component.
+     * @param component   The parent navigation {@link Component}.
+     */
+    protected NavigationItem newBreadcrumbItem(@NotNull final Page page,
+                                               final boolean active,
+                                               @NotNull final LinkManager linkManager,
+                                               final int level,
+                                               final String parentId,
+                                               final Component component) {
+        return new BreadcrumbItemImpl(page, active, linkManager, level, parentId, component);
     }
 
-    private boolean checkIfNotHidden(Page page) {
-        return !page.isHideInNav() || showHidden;
+    /**
+     * Check if a page should be shown in the breadcrumb
+     * A page should be shown if either
+     * <ul>
+     *     <li>`showHidden` is set to true for this component; or,</li>
+     *     <li>The page is not configured to be hidden in navigation</li>
+     * </ul>
+     *
+     * @param page The page to check.
+     * @return True if the page should be shown in the breadcrumb, false if not.
+     */
+    private boolean checkIfNotHidden(@NotNull final Page page) {
+        return this.showHidden || !page.isHideInNav();
     }
 }

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/models/v1/BreadcrumbItemImpl.java

@@ -16,7 +16,7 @@
 
 package com.adobe.cq.wcm.core.components.internal.models.v1;
 
-import java.util.List;
+import java.util.Collections;
 
 import org.jetbrains.annotations.NotNull;
 
@@ -28,12 +28,29 @@
 
 import static org.apache.sling.api.SlingConstants.PROPERTY_PATH;
 
-@JsonIgnoreProperties(value = {"page", "children", "level", "description", "lastModified",PROPERTY_PATH})
+/**
+ * V1 Breadcrumb Item Implementation.
+ */
+@JsonIgnoreProperties(value = {"page", "children", "level", "description", "lastModified", PROPERTY_PATH})
 public class BreadcrumbItemImpl extends NavigationItemImpl implements NavigationItem {
 
-    public BreadcrumbItemImpl(Page page, boolean active, @NotNull LinkManager linkManager, int level,
-                              List<NavigationItem> children, String parentId, Component component) {
-        super(page, active, active, linkManager, level, children, parentId, component);
+    /**
+     * Construct a Breadcrumb Item.
+     *
+     * @param page        The page for which to create a breadcrumb item.
+     * @param active      Flag indicating if the breadcrumb item is active.
+     * @param linkManager Link manager service.
+     * @param level       Depth level of the navigation item.
+     * @param parentId    ID of the parent navigation component.
+     * @param component   The parent navigation {@link Component}.
+     */
+    public BreadcrumbItemImpl(@NotNull final Page page,
+                              final boolean active,
+                              @NotNull final LinkManager linkManager,
+                              final int level,
+                              final String parentId,
+                              final Component component) {
+        super(page, active, active, linkManager, level, Collections::emptyList, parentId, component);
     }
 
 }

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/models/v1/LanguageNavigationImpl.java

@@ -19,6 +19,8 @@
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Optional;
+import java.util.function.Supplier;
 
 import javax.annotation.PostConstruct;
 
@@ -45,18 +47,25 @@
 import com.day.cq.wcm.api.components.Component;
 import com.day.cq.wcm.api.designer.Style;
 
+/**
+ * V1 Language Navigation model implementation.
+ */
 @Model(adaptables = SlingHttpServletRequest.class,
-       adapters = {LanguageNavigation.class, ComponentExporter.class},
-       resourceType = {LanguageNavigationImpl.RESOURCE_TYPE})
-@Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME ,
-          extensions = ExporterConstants.SLING_MODEL_EXTENSION)
+    adapters = {LanguageNavigation.class, ComponentExporter.class},
+    resourceType = {LanguageNavigationImpl.RESOURCE_TYPE})
+@Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME,
+    extensions = ExporterConstants.SLING_MODEL_EXTENSION)
 public class LanguageNavigationImpl extends AbstractComponentImpl implements LanguageNavigation {
 
+    /**
+     * V2 Language Navigation resource type.
+     */
     public static final String RESOURCE_TYPE = "core/wcm/components/languagenavigation/v1/languagenavigation";
-    private static final String PN_ACCESSIBILITY_LABEL = "accessibilityLabel";
 
-    @Self
-    private SlingHttpServletRequest request;
+    /**
+     * Property name for the accessibility lavel.
+     */
+    private static final String PN_ACCESSIBILITY_LABEL = "accessibilityLabel";
 
     @ScriptVariable
     private Page currentPage;
@@ -73,23 +82,23 @@ public class LanguageNavigationImpl extends AbstractComponentImpl implements Lan
     @Nullable
     private String accessibilityLabel;
 
+    @Nullable
     private String navigationRoot;
     private int structureDepth;
-    private Page rootPage;
     private List<NavigationItem> items;
     private int startLevel;
 
     @PostConstruct
     private void initModel() {
-        navigationRoot = properties.get(PN_NAVIGATION_ROOT, currentStyle.get(PN_NAVIGATION_ROOT, String.class));
+        navigationRoot = Optional.ofNullable(properties.get(PN_NAVIGATION_ROOT, String.class))
+            .orElseGet(() -> currentStyle.get(PN_NAVIGATION_ROOT, String.class));
         structureDepth = properties.get(PN_STRUCTURE_DEPTH, currentStyle.get(PN_STRUCTURE_DEPTH, 1));
     }
 
     @Override
     public List<NavigationItem> getItems() {
         if (items == null) {
-            PageManager pageManager = currentPage.getPageManager();
-            rootPage = pageManager.getPage(navigationRoot);
+            Page rootPage = Optional.ofNullable(this.navigationRoot).map(currentPage.getPageManager()::getPage).orElse(null);
             if (rootPage != null) {
                 int rootPageLevel = rootPage.getDepth();
                 startLevel = rootPageLevel + 1;
@@ -111,44 +120,64 @@ public String getAccessibilityLabel() {
         return this.accessibilityLabel;
     }
 
-    @NotNull
-    @Override
-    public String getExportedType() {
-        return request.getResource().getResourceType();
-    }
-
-    private List<NavigationItem> getItems(Page root) {
+    /**
+     * Get localized navigation items under a given page.
+     *
+     * @param root The page.
+     * @return Localized navigation items based on the children of `Page`.
+     */
+    private List<NavigationItem> getItems(@NotNull final Page root) {
         List<NavigationItem> pages = new ArrayList<>();
         if (root.getDepth() < structureDepth) {
             Iterator<Page> it = root.listChildren(new PageFilter());
             while (it.hasNext()) {
-                Page page = it.next();
-                boolean active = currentPage.getPath().equals(page.getPath()) || currentPage.getPath().startsWith(page.getPath() + "/");
-                String title = page.getNavigationTitle();
-                if (title == null) {
-                    title = page.getTitle();
-                }
-                List<NavigationItem> children = getItems(page);
+                final Page page = it.next();
+                String title = PageListItemImpl.getTitle(page);
                 int level = page.getDepth() - startLevel;
-                Page localizedPage = getLocalizedPage(currentPage, page);
-                if (localizedPage != null) {
-                    page = localizedPage;
-                }
-                boolean current = currentPage.getPath().equals(page.getPath());
-                pages.add(newLanguageNavigationItem(page, active, current, linkManager, level, children, title, getId(), component));
+                Page targetPage = Optional.ofNullable(getLocalizedPage(currentPage, page)).orElse(page);
+                boolean current = currentPage.getPath().equals(targetPage.getPath());
+                boolean active = currentPage.getPath().equals(page.getPath()) || currentPage.getPath().startsWith(page.getPath() + "/");
+                pages.add(newLanguageNavigationItem(targetPage, active, current, linkManager, level, () -> getItems(page), title, getId(), component));
             }
         }
 
         return pages;
     }
 
-    protected LanguageNavigationItem newLanguageNavigationItem(Page page, boolean active, boolean current, @NotNull LinkManager linkManager,
-                                                               int level, List<NavigationItem> children, String title, String parentId,
-                                                               Component component) {
-        return new LanguageNavigationItemImpl(page, active, current, linkManager, level, children, title, parentId, component);
+    /**
+     * Construct a Navigation Item.
+     *
+     * @param page             The page for which to create a navigation item.
+     * @param active           Flag indicating if the navigation item is active.
+     * @param current          Flag indicating if the navigation item is current page.
+     * @param linkManager      Link manager service.
+     * @param level            Depth level of the navigation item.
+     * @param childrenSupplier The child navigation items supplier.
+     * @param title            The item title.
+     * @param parentId         ID of the parent navigation component.
+     * @param component        The parent navigation {@link Component}.
+     */
+    protected LanguageNavigationItem newLanguageNavigationItem(@NotNull final Page page,
+                                                               final boolean active,
+                                                               final boolean current,
+                                                               @NotNull final LinkManager linkManager,
+                                                               final int level,
+                                                               @NotNull final Supplier<List<NavigationItem>> childrenSupplier,
+                                                               final String title,
+                                                               final String parentId,
+                                                               final Component component) {
+        return new LanguageNavigationItemImpl(page, active, current, linkManager, level, childrenSupplier, title, parentId, component);
     }
 
-    private Page getLocalizedPage(Page page, Page languageRoot) {
+    /**
+     * Get the localized version of page found under the `languageRoot`.
+     *
+     * @param page The page for which to get the localized page.
+     * @param languageRoot The language root page for the locale under which to find the localized page.
+     * @return The localized page under languageRoot, or null if no such page exists.
+     */
+    @Nullable
+    private Page getLocalizedPage(@NotNull final Page page, @NotNull final Page languageRoot) {
         Page localizedPage;
         String path = languageRoot.getPath();
         String relativePath = page.getPath();

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/models/v1/LanguageNavigationItemImpl.java

@@ -17,6 +17,7 @@
 
 import java.util.List;
 import java.util.Locale;
+import java.util.function.Supplier;
 
 import org.jetbrains.annotations.NotNull;
 
@@ -28,21 +29,61 @@
 import com.day.cq.wcm.api.Page;
 import com.day.cq.wcm.api.components.Component;
 
+/**
+ * V1 Language Navigation Item implementation.
+ */
 public class LanguageNavigationItemImpl extends NavigationItemImpl implements LanguageNavigationItem {
 
-    protected String title;
-    protected Locale locale;
-    protected String country;
-    protected String language;
+    /**
+     * Navigation item title.
+     */
+    private final String title;
 
-    public LanguageNavigationItemImpl(Page page, boolean active, boolean current, @NotNull LinkManager linkManager, int level,
-                                      List<NavigationItem> children, String title, String parentId, Component component) {
-        super(page, active, current, linkManager, level, children, parentId, component);
+    /**
+     * Locale for this language navigation item.
+     */
+    private Locale locale;
+
+    /**
+     * Country for this language navigation item.
+     */
+    private String country;
+
+    /**
+     * Language for this language navigation item.
+     */
+    private String language;
+
+    /**
+     * Construct a Language Navigation Item.
+     *
+     * @param page             The page for which to create a navigation item.
+     * @param active           Flag indicating if the navigation item is active.
+     * @param current          Flag indicating if the navigation item is current page.
+     * @param linkManager      Link manager service.
+     * @param level            Depth level of the navigation item.
+     * @param childrenSupplier The child navigation items supplier.
+     * @param title            The item title.
+     * @param parentId         ID of the parent navigation component.
+     * @param component        The parent navigation {@link Component}.
+     */
+    public LanguageNavigationItemImpl(@NotNull final Page page,
+                                      final boolean active,
+                                      final boolean current,
+                                      @NotNull final LinkManager linkManager,
+                                      final int level,
+                                      @NotNull final Supplier<List<NavigationItem>> childrenSupplier,
+                                      final String title,
+                                      final String parentId,
+                                      final Component component) {
+        super(page, active, current, linkManager, level, childrenSupplier, parentId, component);
         this.title = title;
     }
 
     @Override
-    public String getTitle() { return title; }
+    public String getTitle() {
+        return title;
+    }
 
     @Override
     public Locale getLocale() {