docs: make the list of available versions dynamic

Make the list of available versions dynamic. The items displayed is now
generated with javascript. The parent directory of the site is supposed
to contain versions.js providing getVersionListItems() that returns the
available versions.

The update-gh-pages.sh script is modified to update/create versions.js
on every invocation. It simply lists all directories in the root
directory and adds them to the version list.

docs/_config.yml

@@ -40,9 +40,7 @@ remote_theme: rundocs/jekyll-rtd-theme@v2.0.9
 #   - vendor/gems/
 #   - vendor/ruby/
 
-# Document versioning. Current 'version' should be listed under
+# Document versioning
-# 'versions' as we use it in constructing the baseurl for other
-# versions.
 version: master
-versions:
+display_version_list: true
-  - master
+

docs/_includes/class/addons-wrap.liquid

@@ -1,30 +1,30 @@
 <div class="addons-wrap d-flex flex-column overflow-y-auto">
     <div class="branch">
         <dl>
-            <dt>Versions:</dt>
+            {% if site.display_version_list %}
+                <dt id="versions">Versions:</dt>
 
-            {% comment %}
+                {% comment %}
-            The following ugly construction is solely for the
+                Drop the last component from site.baseurl which is supposed to
-            purpose of dropping the "version" suffix from the
+                be pointing to a subdirectory of the true site baseurl.
-            baseurl. The reason for doing this is that github-pages
+                {% endcomment %}
-            gem forces us on --safe mode (i.e. disables custom
+                {% assign spliturl = site.baseurl | split: "/" %}
-            plugins) so we're not able to write a simple ruby
+                {% assign last = spliturl.size | minus: 1 %}
-            plugin doing delete_suffix()
+                {% assign baseurl = spliturl | slice: 0, last | join: "/" %}
-            {% endcomment %}
+
-            {% assign version_len = site.version | size %}
+                <script src="{{ baseurl }}/versions.js"></script>
-            {% assign baseurl_len = site.baseurl | size %}
+                <script>
-            {% assign idx = baseurl_len | minus: version_len %}
+                    var dt = document.getElementById('versions');
-            {% assign suffix = site.baseurl | slice: idx, version_len %}
+                    var items = getVersionListItems();
-            {% if suffix == site.version %}
+                    for (var i=0; i < items.length; i++) {
-                {% assign idx = idx | minus: 1 %}
+                      var dd = document.createElement('dd');
-                {% assign baseurl = site.baseurl | slice: 0, idx %}
+                      var a = dd.appendChild(document.createElement('a'));
-            {% else %}
+                      a.appendChild(document.createTextNode(items[i].name));
-                {% assign baseurl = site.baseurl %}
+                      a.href = items[i].url;
+                      dt.appendChild(dd);
+                    }
+                </script>
             {% endif %}
-
-            {% for version in site.versions %}
-                <dd><a href="{{ baseurl }}/{{ version }}/">{{ version }}</a></dd>
-            {% endfor %}
         </dl>
     </div>
     <div class="status d-flex flex-justify-between p-2">

scripts/github/update-gh-pages.sh

@@ -14,6 +14,19 @@ Options:
 EOF
 }
 
+# Helper function for detecting available versions from the current directory
+create_versions_js() {
+    local _baseurl="/node-feature-discovery"
+
+    echo -e "function getVersionListItems() {\n  return ["
+    # 'stable' is a symlink pointing to the latest version
+    [ -f stable ] && echo "    { name: 'stable', url: '$_baseurl/stable' },"
+    for f in `ls -d */  | tr -d /` ; do
+        echo "    { name: '$f', url: '$_baseurl/$f' },"
+    done
+    echo -e "  ];\n}"
+}
+
 #
 # Argument parsing
 #
@@ -106,6 +119,9 @@ cd "$build_dir"
 _stable=`(ls -d1 v*/ || :) | sort -n | tail -n1`
 [ -n "$_stable" ] && ln -sfT "$_stable" stable
 
+# Detect existing versions from the gh-pages branch
+create_versions_js > versions.js
+
 if [ -z "`git status --short`" ]; then
     echo "No new content, gh-pages branch already up-to-date"
     exit 0