feat(v2): global data + useGlobalData + docs versions dropdown (#2971)

* doc components initial simplification

* doc components initial simplification

* add docContext test

* Add poc of global data system + use it in the theme

* Revert "doc components initial simplification"

This reverts commit f657b4c4

* revert useless changes

* avoid loosing context on docs switch

* fix docs tests

* fix @generated/globalData ts declaration / es import

* typo

* revert bad commit

* refactor navbar in multiple parts + add navbar item types validation + try to fix remaining merge bugs

* add missing watch mode for plugin debug

* fix docs global data integration, move related hooks to docs plugin + convert to TS

* change versions link label

* fix activeClassName react warning

* improve docs global data system + contextual navbar dropdown

* fix bug preventing the deployment

* refactor the global data system to namespace automatically by plugin name + plugin id

* proper NavbarItem comp

* fix tests

* fix snapshot

* extract theme config schema in separate file + rename navbar links to navbar items

* minor typos

* polish docs components/api

* polish useDocs api surface

* fix the docs version suggestions comp + data

* refactors + add docsClientUtils unit tests

* Add documentation

* typo

* Add check for duplicate plugin ids detection

* multi-instance: createData plugin data should be namespaced by plugin instance id

* remove attempt for multi-instance support

packages/docusaurus-plugin-content-docs/src/theme/hooks/useDocs.ts

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {useLocation} from '@docusaurus/router';
+import {
+  useAllPluginInstancesData,
+  usePluginData,
+} from '@docusaurus/useGlobalData';
+
+import {GlobalPluginData, GlobalVersion} from '../../types';
+import {
+  getActivePlugin,
+  getLatestVersion,
+  getActiveVersion,
+  getActiveDocContext,
+  getDocVersionSuggestions,
+} from '../../client/docsClientUtils';
+
+const useAllDocsData = (): Record<string, GlobalPluginData> =>
+  useAllPluginInstancesData('docusaurus-plugin-content-docs');
+
+const useDocsData = (pluginId: string | undefined) =>
+  usePluginData('docusaurus-plugin-content-docs', pluginId) as GlobalPluginData;
+
+export const useActivePlugin = () => {
+  const data = useAllDocsData();
+  const {pathname} = useLocation();
+  return getActivePlugin(data, pathname);
+};
+
+// versions are returned ordered (most recent first)
+export const useVersions = (pluginId: string | undefined): GlobalVersion[] => {
+  const data = useDocsData(pluginId);
+  return data.versions;
+};
+
+export const useLatestVersion = (pluginId: string | undefined) => {
+  const data = useDocsData(pluginId);
+  return getLatestVersion(data);
+};
+
+// Note: return undefined on doc-unrelated pages,
+// because there's no version currently considered as active
+export const useActiveVersion = (pluginId: string | undefined) => {
+  const data = useDocsData(pluginId);
+  const {pathname} = useLocation();
+  return getActiveVersion(data, pathname);
+};
+
+export const useActiveDocContext = (pluginId: string | undefined) => {
+  const data = useDocsData(pluginId);
+  const {pathname} = useLocation();
+  return getActiveDocContext(data, pathname);
+};
+
+// Useful to say "hey, you are not on the latest docs version, please switch"
+export const useDocVersionSuggestions = (pluginId: string | undefined) => {
+  const data = useDocsData(pluginId);
+  const {pathname} = useLocation();
+  return getDocVersionSuggestions(data, pathname);
+};