Don't allow to set child element as parent. (#19)

* filter available pages

* refactor

set function as method of Pages

* change wrong word

* change commentaries

* change method name

* refactor

refactor

* Update src/controllers/pages.js

Co-Authored-By: cabad11 <44175180+cabad11@users.noreply.github.com>

* refactor

change comments
change metod name

src/controllers/pages.js

@@ -41,6 +41,38 @@ class Pages {
     return Model.getAll();
   }
 
+  /**
+   * @static
+   * Return all pages without children of passed page
+   *
+   * @param {string} parent - id of current page
+   * @returns {Promise<Page[]>}
+   */
+  static async getAllExceptChildrens(parent) {
+    let pagesAvailable = this.removeChildren(await Pages.getAll(), parent);
+
+    return pagesAvailable.filter((item) => item !== null);
+  }
+
+  /**
+   * @static
+   * Set all children elements to null
+   *
+   * @param {Page[]} [pagesAvailable] - Array of all pages
+   * @param {string} parent - id of parent page
+   * @returns {Array<?Page>}
+   */
+  static removeChildren(pagesAvailable, parent) {
+    pagesAvailable.forEach(async (item, index) => {
+      if (item === null || item._parent !== parent) {
+        return;
+      }
+      pagesAvailable[index] = null;
+      pagesAvailable = Pages.removeChildren(pagesAvailable, item._id);
+    });
+    return pagesAvailable;
+  }
+
   /**
    * Create new page model and save it in the database
    *

src/routes/pages.js

@@ -22,7 +22,7 @@ router.get('/page/edit/:id', async (req, res, next) => {
 
   try {
     let page = await Pages.get(pageId);
-    let pagesAvailable = await Pages.getAll();
+    let pagesAvailable = await Pages.getAllExceptChildrens(pageId);
 
     res.render('pages/form', {
       pagesAvailable,