fix(i18n): strip existing language prefix in manage language switch

mandelstudio/templates/oxyan/headers/partials/carbasa-user-bar.html

@@ -1,9 +1,9 @@
-{% load i18n i18n_helpers %}
+{% load i18n mandelstudio_i18n %}
 {% get_current_language as LANGUAGE_CODE %}
 <div class="header-right">
     <form action="{% url 'set_language' %}" method="post" class="ms-lang-switcher me-2" aria-label="Language switcher">
         {% csrf_token %}
-        <input name="next" type="hidden" value="{{ language_neutral_url_path|default:request.path|untranslated_url }}">
+        <input name="next" type="hidden" value="{{ language_neutral_url_path|default:request.path|language_neutral_path }}">
         <label for="header-language-switcher" class="visually-hidden">{% trans "Language" %}</label>
         <select id="header-language-switcher" name="language" class="form-select form-select-sm" onchange="this.form.submit()">
             <option value="nl" {% if LANGUAGE_CODE == 'nl' %}selected{% endif %}>NL</option>

mandelstudio/templates/oxyan/partials/language_chooser.html

@@ -1,5 +1,5 @@
 <!-- MB OVERRIDE -->
-{% load i18n static ocyanjson i18n_helpers %}
+{% load i18n static ocyanjson mandelstudio_i18n %}
 
 <div class="dropdown language-dropdown">
     <button type="button" id="dropdownMenuButton1" data-bs-toggle="dropdown" aria-expanded="false">
@@ -10,7 +10,7 @@
         {% ocyanjson "i18n" "language_chooser_disabled_options" "" as disabled_languages %}
         <form action="{% url 'set_language' %}" method="post" class="language_form">
             {% csrf_token %}
-            <input name="next" type="hidden" value="{{ language_neutral_url_path|default:request.path|untranslated_url }}"/>
+            <input name="next" type="hidden" value="{{ language_neutral_url_path|default:request.path|language_neutral_path }}"/>
             {% for language in languages %}
                 {% if language.code not in disabled_languages %}
                     <li><button class="dropdown-item" type="submit" value="{{language.code}}" name="language">{% include "oxyan/partials/flags/"|add:language.code|add:".svg" %} {{ language.name_local|title }}</button></li>

mandelstudio/templatetags/mandelstudio_i18n.py

@@ -1,6 +1,10 @@
 from __future__ import annotations
 
+import re
+from urllib.parse import urlsplit, urlunsplit
+
 from django import template
+from django.conf import settings
 
 register = template.Library()
 
@@ -21,3 +25,23 @@ def skip_to_content_text(context) -> str:
     request = context.get("request")
     language_code = getattr(request, "LANGUAGE_CODE", "nl")
     return SKIP_TO_CONTENT.get(language_code, SKIP_TO_CONTENT["en"])
+
+
+@register.filter(name="language_neutral_path")
+def language_neutral_path(value: str | None) -> str:
+    """Normalize a path for set_language by removing any leading language prefix."""
+    if not value:
+        return "/"
+
+    parsed = urlsplit(str(value))
+    path = parsed.path or "/"
+    if not path.startswith("/"):
+        path = f"/{path}"
+
+    language_codes = [code for code, _ in settings.LANGUAGES]
+    if language_codes:
+        # Strip the first language segment, e.g. /en/manage -> /manage.
+        pattern = rf"^/(?:{'|'.join(re.escape(code) for code in language_codes)})(?=/|$)"
+        path = re.sub(pattern, "", path, count=1) or "/"
+
+    return urlunsplit(("", "", path, parsed.query, ""))

mandelstudio/tests/test_mandelstudio_i18n_templatetags.py

@@ -0,0 +1,31 @@
+from django.test import SimpleTestCase, override_settings
+
+from mandelstudio.templatetags.mandelstudio_i18n import language_neutral_path
+
+
+@override_settings(
+    LANGUAGES=(
+        ("nl", "Dutch"),
+        ("en", "English"),
+        ("de", "German"),
+        ("fr", "French"),
+        ("es", "Spanish"),
+        ("it", "Italian"),
+        ("pt", "Portuguese"),
+        ("ru", "Russian"),
+    )
+)
+class LanguageNeutralPathFilterTests(SimpleTestCase):
+    def test_strips_language_prefix(self):
+        self.assertEqual(language_neutral_path("/en/manage/"), "/manage/")
+        self.assertEqual(language_neutral_path("/fr/manage/checkout/paymentmethod/"), "/manage/checkout/paymentmethod/")
+
+    def test_keeps_unprefixed_path(self):
+        self.assertEqual(language_neutral_path("/manage/"), "/manage/")
+        self.assertEqual(language_neutral_path("/manage/checkout/paymentmethod/"), "/manage/checkout/paymentmethod/")
+
+    def test_preserves_query_string(self):
+        self.assertEqual(
+            language_neutral_path("/de/manage/?next=/de/manage/checkout/paymentmethod/"),
+            "/manage/?next=/de/manage/checkout/paymentmethod/",
+        )