docs(nav): fix sidebar nesting, dynamic language switcher, and delete translations page (#5535)

docs/_includes/head_custom.html

@@ -125,7 +125,8 @@
   .language-switcher-list {
     position: absolute;
     top: 100%;
-    left: 0;
+    right: 0;
+    left: auto;
     z-index: 100;
     list-style: none;
     padding: 8px 0;

docs/_includes/language_switcher.html

@@ -6,49 +6,49 @@
   Usage: {% include language_switcher.html %}
 
   Logic:
-  - Derives the current page's relative path within its section
-  - Checks if translated versions exist in locale subdirectories
-  - Shows a globe icon with available locale links
+  - Dynamically detects the current language and page name.
+  - Dynamically updates the switcher button's native language name.
+  - Correctly matches English pages to translated equivalents and vice versa.
+  - Pre-verifies existing files to only render valid, non-404 options.
 {% endcomment %}
 
 {% assign current_path = page.path %}
 {% assign locales = site.data.locales %}
 
 {% if locales and current_path %}
-{% assign path_parts = current_path | split: "/" %}
-{% assign first_segment = path_parts[0] %}
+  {% assign path_parts = current_path | split: "/" %}
+  {% assign first_segment = path_parts[0] %}
 
-{% comment %} Build the list of available translations first {% endcomment %}
-{% assign has_translations = false %}
+  {% comment %}
+    Identify the current page's language code and native language name.
+    If the first segment is defined in locales.yml, we are on a translation.
+    Otherwise, we are in default English.
+  {% endcomment %}
+  {% if locales[first_segment] %}
+    {% assign current_lang_code = first_segment %}
+    {% assign current_lang_name = locales[first_segment].name %}
+  {% else %}
+    {% assign current_lang_code = "en" %}
+    {% assign current_lang_name = "English" %}
+  {% endif %}
 
-{% if locales[first_segment] %}
-  {% comment %} We're on a translated page — English link is always available {% endcomment %}
-  {% assign has_translations = true %}
+  {% comment %}
+    Extract the relative base path (independent of locale prefix and file extension).
+    E.g., "en/user/connections.md" and "be-rBY/user/connections.md" both resolve to "user/connections".
+  {% endcomment %}
   {% assign remaining_parts = path_parts | slice: 1, path_parts.size %}
-  {% assign en_path = remaining_parts | join: "/" | replace: ".md", "" %}
-{% else %}
-  {% comment %} Check if any translated version exists {% endcomment %}
-  {% assign en_relative = current_path | replace: ".md", "" %}
-  {% for locale in locales %}
-    {% assign locale_code = locale[0] %}
-    {% assign locale_file = locale_code | append: "/" | append: en_relative | append: ".md" %}
-    {% for p in site.pages %}
-      {% if p.path == locale_file %}
-        {% assign has_translations = true %}
-        {% break %}
-      {% endif %}
-    {% endfor %}
-    {% if has_translations %}{% break %}{% endif %}
-  {% endfor %}
-{% endif %}
+  {% assign base_path = remaining_parts | join: "/" | replace: ".md", "" %}
 
-{% if has_translations %}
-<details class="language-switcher" aria-label="Language options">
-  <summary class="language-switcher-btn" title="View in another language">
-    🌐 <span class="lang-current">English</span>
-  </summary>
-  <ul class="language-switcher-list">
-    {% if locales[first_segment] %}
+  {% comment %}
+    Pre-render the dropdown list items.
+  {% endcomment %}
+  {% capture dropdown_items %}
+    {% if current_lang_code != "en" %}
+      {% if base_path == "index" %}
+        {% assign en_path = "en/" %}
+      {% else %}
+        {% assign en_path = "en/" | append: base_path %}
+      {% endif %}
       <li><a href="{{ en_path | relative_url }}" lang="en">English</a></li>
     {% endif %}
 
@@ -56,16 +56,12 @@
       {% assign locale_code = locale[0] %}
       {% assign locale_info = locale[1] %}
 
-      {% if locales[first_segment] %}
-        {% if locale_code == first_segment %}
-          {% continue %}
-        {% endif %}
-        {% assign locale_path = locale_code | append: "/" | append: en_path %}
-      {% else %}
-        {% assign locale_path = locale_code | append: "/" | append: en_relative %}
+      {% if locale_code == current_lang_code %}
+        {% continue %}
       {% endif %}
 
-      {% assign locale_file = locale_path | append: ".md" %}
+      {% assign locale_file = locale_code | append: "/" | append: base_path | append: ".md" %}
+
       {% assign page_exists = false %}
       {% for p in site.pages %}
         {% if p.path == locale_file %}
@@ -75,10 +71,29 @@
       {% endfor %}
 
       {% if page_exists %}
+        {% if base_path == "index" %}
+          {% assign locale_path = locale_code | append: "/" %}
+        {% else %}
+          {% assign locale_path = locale_code | append: "/" | append: base_path %}
+        {% endif %}
         <li><a href="{{ locale_path | relative_url }}" lang="{{ locale_code }}" {% if locale_info.dir == "rtl" %}dir="rtl"{% endif %}>{{ locale_info.name }}</a></li>
       {% endif %}
     {% endfor %}
-  </ul>
-</details>
-{% endif %}
+  {% endcapture %}
+
+  {% assign dropdown_items_stripped = dropdown_items | strip %}
+
+  {% comment %}
+    Only render the switcher if there is at least one other language option available.
+  {% endcomment %}
+  {% if dropdown_items_stripped != "" %}
+    <details class="language-switcher" aria-label="Language options">
+      <summary class="language-switcher-btn" title="View in another language">
+        🌐 <span class="lang-current">{{ current_lang_name }}</span>
+      </summary>
+      <ul class="language-switcher-list">
+        {{ dropdown_items }}
+      </ul>
+    </details>
+  {% endif %}
 {% endif %}