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

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

@@ -0,0 +1,97 @@
+/**
+ * @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 { NgxStructureService } from './structure.service';
+import { NgxMenuService } from './menu.service';
+
+/**
+ * Pagination Item options
+ */
+class NgxPaginationItem {
+  title: string;
+  slag: string;
+  link?: string;
+  prev?: {
+    title: string;
+    link: string;
+  };
+  next?: {
+    title: string;
+    link: string;
+  };
+  parent: NgxPaginationItem;
+}
+
+@Injectable()
+export class NgxPaginationService {
+
+  protected paginationItems;
+
+  constructor(private structureService: NgxStructureService,
+              private menuService: NgxMenuService) {
+  }
+
+  setPaginationItems(basePath: string) {
+    this.paginationItems = this.addPrevNextPointers(
+      this.prepareItems(
+        this.structureService.getPreparedStructure(),
+        { link: basePath },
+        ),
+    );
+  }
+
+  protected prepareItems(structure, parent = null): NgxPaginationItem[] {
+    return structure
+        .filter(item => item.name)
+        .reduce((result, item: any) => {
+          const paginationItem: NgxPaginationItem = {
+            title: item.name,
+            parent: parent,
+            slag: item.slag,
+          };
+          paginationItem.link = this.menuService.createItemLink<NgxPaginationItem>(paginationItem);
+
+          if (item.name && item.type === 'page' || item.type === 'tabs') {
+            result.push(paginationItem);
+          }
+
+          if (item.children) {
+            return result.concat(this.prepareItems(item.children, paginationItem));
+          }
+
+          return result;
+      }, [] as NgxPaginationItem[]);
+  }
+
+  protected addPrevNextPointers(items): NgxPaginationItem[] {
+    return items
+      .map((paginationItem, index, paginationItems) => {
+        const prev = paginationItems[index - 1];
+        const next = paginationItems[index + 1];
+
+        if (prev) {
+          paginationItem.prev = {
+            link: prev.link,
+            title: prev.title,
+          };
+        }
+
+        if (next) {
+          paginationItem.next = {
+            link: next.link,
+            title: next.title,
+          };
+        }
+
+        return paginationItem;
+      });
+  }
+
+  getPaginationItem(slag: string): NgxPaginationItem {
+    return this.paginationItems.find(item => item.slag === slag);
+  }
+}