feat: sub-categories in sidebar.json (#892)

* Add ability to specify sub categories in sidebar.json

* move v1 files to correct place

* refactor implementation

* refactor naming for implementation clarity

v1/lib/core/DocsSidebar.js

@@ -6,15 +6,31 @@
  */
 
 const React = require('react');
+const fs = require('fs');
 const Container = require('./Container.js');
 const SideNav = require('./nav/SideNav.js');
+const Metadata = require('../core/metadata.js');
 const readCategories = require('../server/readCategories.js');
 
+let languages;
+
+if (fs.existsSync(`../server/languages.js`)) {
+  languages = require(`../server/languages.js`);
+} else {
+  languages = [
+    {
+      enabled: true,
+      name: 'English',
+      tag: 'en',
+    },
+  ];
+}
+
 class DocsSidebar extends React.Component {
   render() {
     const sidebar = this.props.metadata.sidebar;
-    const docsCategories = readCategories(sidebar);
-    const categoryName = docsCategories[this.props.metadata.language][0].name;
+    const docsCategories = readCategories(sidebar, Metadata, languages);
+    const categoryName = this.props.metadata.category;
     if (!categoryName) {
       return null;
     }

v1/lib/core/nav/SideNav.js

@@ -67,7 +67,22 @@ class SideNav extends React.Component {
         <h3 className="navGroupCategoryTitle">
           {this.getLocalizedCategoryString(category.name)}
         </h3>
-        <ul>{category.links.map(this.renderItemLink, this)}</ul>
+        <ul>
+          {category.links.map(this.renderItemLink, this)}
+          {category.sub_categories &&
+            category.sub_categories.map(this.renderSubCategory, this)}
+        </ul>
+      </div>
+    );
+  }
+
+  renderSubCategory(subCategory) {
+    return (
+      <div className="navGroup subNavGroup" key={subCategory.name}>
+        <h4 className="navGroupSubCategoryTitle">
+          {this.getLocalizedCategoryString(subCategory.name)}
+        </h4>
+        <ul>{subCategory.links.map(this.renderItemLink, this)}</ul>
       </div>
     );
   }