feat(demo): add landing page with docs (#1951)

docs/app/@theme/services/menu.service.ts

@@ -0,0 +1,86 @@
+/**
+ * @license
+ * Copyright Akveo. All Rights Reserved.
+ * Licensed under the MIT License. See License.txt in the project root for license information.
+ */
+
+import { Injectable } from '@angular/core';
+import { NbMenuItem } from '@nebular/theme';
+
+import { NgxStructureService } from './structure.service';
+import { NgxTextService } from './text.service';
+
+interface IItemLink {
+  title: string;
+  parent?: {
+    link?: string;
+  };
+}
+
+@Injectable()
+export class NgxMenuService {
+
+  constructor(private structureService: NgxStructureService,
+              private textService: NgxTextService) {
+  }
+
+  getPreparedMenu(basePath: string): any {
+    return this.prepareMenu(this.structureService.getPreparedStructure(), { link: basePath });
+  }
+
+  prepareMenu(structure, parent = null) {
+    return structure
+      .filter(item => item.name && item.type !== 'block')
+      .map((item: any) => {
+        const menuItem: NbMenuItem = {
+          title: item.name,
+          pathMatch: 'prefix',
+          parent: parent,
+          data: item,
+          group: item.type === 'group',
+        };
+        menuItem.link = this.createItemLink<NbMenuItem>(menuItem);
+
+        if (item.children && item.children.some(child => child.type === 'page' || child.type === 'tabs')) {
+          menuItem.expanded = true;
+          menuItem.children = this.prepareMenu(item.children, menuItem);
+        }
+
+        return menuItem;
+      });
+  }
+
+  protected prepareToc(item: any) {
+    return item.children.reduce((acc: any[], child: any) => {
+      if (child.block === 'markdown') {
+        return acc.concat(this.getTocForMd(child));
+      } else if (child.block === 'tabbed') {
+        return acc.concat(this.getTocForTabbed(child));
+      }
+      acc.push(child.source.name);
+      return acc;
+    }, []);
+  }
+
+  protected getTocForMd(block: any) {
+    return block.children.map((section: any) => ({
+      title: section.title,
+      fragment: section.fragment,
+    }));
+  }
+
+  protected getTocForTabbed(block: any) {
+    return block.children.map((component: any) => (
+      {
+        title: component.name,
+        fragment: this.textService.createSlag(component.name),
+      }
+    ));
+  }
+
+  createItemLink<T extends IItemLink>(item: T): string {
+    const url = this.textService.createSlag(item.title);
+
+    return item.parent ? `${item.parent.link}/${url}` : url;
+  }
+}