[TASK] Improve AJAX version switcher to sort and group languages and …

…links, document workflow (#583)

Documentation/Developer/AjaxVersions.rst

@@ -0,0 +1,113 @@
+..  include:: /Includes.rst.txt
+
+..  _AjaxVersions:
+
+=====================
+AJAX version switcher
+=====================
+
+Rendered documentation provides a version switcher on top of the
+navigation.
+
+For documentation deployed on `docs.typo3.org` clicking on the version
+switcher will perform an AJAX API request that lists all available
+versions and languages for the current documentation.
+
+For local rendering however, there are two issues that will lead to
+the version switcher not working properly:
+
+* Rendered HTML files viewed via the `file:///` notation may not
+  execute any JavaScript due to security considerations/configuration
+  of your browser.
+* When viewing HTML files via `localhost` or a `.ddev.site` webserver,
+  the AJAX call will fail due to `CORS <https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS>`__
+  (Cross-Origin Resource Sharing) security restrictions.
+
+Developers of the `render-guides` project may need to simulate menu rendering though.
+
+For them, navigation can be proxied and simulated.
+
+..  _AjaxVersions-proxy:
+
+Making the proxy available
+==========================
+
+When using the DDEV integration to view the documentation, the DocumentRoot of the
+DDEV webserver is set to `Documentation-GENERATED-temp`. This does not
+contain active PHP files by default.
+
+The file :file:`packages/typo3-docs-theme/assets/js/versions-proxy.php` in the
+repository of this project (`<https://github.com/TYPO3-Documentation/render-guides>`)
+can act as a simple proxy. You can copy or symlink that file into your `Documentation-GENERATED-temp`
+directory, so that it is callable with a URL like:
+
+..  code::
+
+    https://render-guides.ddev.site/versions-proxy.php?url=https://docs.typo3.org/m/typo3/tutorial-getting-started/12.4/en-us/Concepts/Index.html
+
+The PHP proxy passes the URL parameter `url` on to the actual `docs.typo3.org` API endpoint,
+and returns its output locally.
+
+Once the proxy PHP file is in place, the default values of the rendering will take effect
+already. See :ref:`AjaxVersions-data-attributes` on how to fine-tune this.
+
+Details on how the version switcher is implemented
+==================================================
+
+Local rendering is automatically detected via the absence of an environment variable
+`TYPO3AZUREEDGEURIVERSION` (see :ref:`deploy-azure-assets`).
+
+This allows a Twig function `isRenderedForDeployment` (defined in
+:file:`packages/typo3-docs-theme/src/Twig/TwigExtension.php` of this repository) to
+conditionally generate output. The Twig template file
+`packages/typo3-docs-theme/resources/template/structure/navigation/navigationHeader.html.twig`
+makes use of that function to define some default HTML data-attributes for out-of-the-box
+version witcher simulation, once the PHP proxy URL can be called without a 404 error.
+
+The JavaScript is contained in :file:`packages/typo3-docs-theme/assets/js/versions.js` and
+contains the code for parsing the JSON response of the API, and sorting the keys appropriately.
+More details can be found inside the code comments of that file.
+
+When changing this JavaScript, the assets must be rebuilt (:bash:`ddev npm-build`) and
+documentation must be rendered with the built assets (:bash:`make docs`).
+
+The JavaScript file also contains some logic to set names for known published translations.
+If a static name is not available, it is resolved to the ISO-code (like "de-de"). The
+TYPO3 Documentation team can not easily access active server-side code to get an automatic
+list of languages.
+
+..  _AjaxVersions-data-attributes:
+Configuring HTML data-attributes
+================================
+
+The following data-attributes on the HTML element :html:`<div id="toc-version">` are available:
+
+*  `data-override-url-self` - This is a full URL starting with `https://docs.typo3.org` which
+   is used as the simulated page from which the version switching information is retrieved for.
+   For example, `https://docs.typo3.org/m/typo3/tutorial-getting-started/12.4/en-us/Concepts/Index.html`.
+
+*  `data-override-url-proxy` - Points to the full URI of the :ref:`AjaxVersions-proxy` PHP proxy.
+   This is called due to CORS reasons. The default of this attribute is set to
+   `https://render-guides.ddev.site/versions-proxy.php?url=`. Unless this file is manually
+   copied to this URL, the proxy will return a 404 failure and inform about the non-working
+   version switcher.
+
+Seeing the simulated output
+===========================
+
+Once the PHP proxy is in place, open the rendered documentation HTML file in your DDEV/webserver
+environment (not using a `file:///` syntax, because then JavaScript may unavailable), for example
+
+..  code::
+
+    https://render-guides.ddev.site/Developer/AjaxVersions.html
+
+You can then also use the browser's JavaScript console to manipulate the used URLs for
+rendering, for example:
+
+..  code::
+
+    document.getElementById('toc-version').setAttribute('data-override-url-self', 'https://docs.typo3.org/other/t3docs/render-guides/main/en-us/Developer/InterlinkInventories.html');
+
+This must be performed before actually clicking the version switcher link, because
+the remote AJAX request is only performed once and then never again without reloading the page.

Documentation/Developer/Building.rst

@@ -200,6 +200,7 @@ above, and then executes two composite steps:
 Note that we only have one central Docker container image entrypoint that can
 take arguments like `migrate` or `render` to trigger different actions.
 
+..  _deploy-azure-assets:
 
 GitHub workflow: deploy-azure-assets
 ------------------------------------

Documentation/Developer/Index.rst

@@ -92,6 +92,7 @@ and the GitHub pipelines, while internally only using :file:`Makefile` syntax.
     Contributing
     ThemeCustomization
     InterlinkInventories
+    AjaxVersions
 
 
 ..  _phpDocumentor/guides: https://github.com/phpDocumentor/guides

Documentation/guides.xml

@@ -6,6 +6,8 @@
 >
     <project
         title="Render guides"
+        version="main"
+        release="main"
         copyright="Since 2023 TYPO3 Documentation Team and Contributors"
     />
     <extension

packages/typo3-docs-theme/assets/js/versions-proxy.php

@@ -0,0 +1,41 @@
+<?php
+
+# This is a Proxy file to request a URL from docs.typo.org
+# and pass the result along to the local development.
+# It is used for debugging the docs.typo3.org/services/versionsJson.php
+# endpoint.
+# Since no active PHP files are part of the local DDEV instance by default,
+# you need to manually put that file into the document root:
+# $> ln -s ../packages/typo3-docs-theme/assets/js/versions-proxy.php Documentation-GENERATED-temp/versions-proxy.php
+
+$proxyUrl = 'https://docs.typo3.org/services/versionsJson.php?url=' . urlencode($_REQUEST['url']);
+
+$ch = curl_init();
+curl_setopt($ch, CURLOPT_URL, $proxyUrl);
+curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+curl_setopt($ch, CURLOPT_HEADER, true);
+$response = curl_exec($ch);
+
+if (curl_errno($ch) || $response === false) {
+    header('404 Not Found');
+    echo 'cURL error: ' . curl_error($ch);
+    curl_close($ch);
+    exit();
+}
+$response = (string)$response;
+
+$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
+$headers = substr($response, 0, $header_size);
+$body = substr($response, $header_size);
+curl_close($ch);
+http_response_code($http_code);
+$headers_array = explode("\r\n", $headers);
+
+foreach($headers_array as $header) {
+    if (!empty($header) && !preg_match('/^Transfer-Encoding:/i', $header) && !preg_match('/^Content-Length:/i', $header)) {
+        header($header);
+    }
+}
+
+echo $body;