from django.utils import translation


class UserLanguageMiddleware:
    """Prefer the authenticated user's saved language over browser/cookie language."""

    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        user = getattr(request, 'user', None)
        language = ''
        if user and user.is_authenticated:
            try:
                language = user.preferences.language
            except Exception:
                language = ''
        if language:
            translation.activate(language)
            request.LANGUAGE_CODE = language
        response = self.get_response(request)
        if language:
            response.setdefault('Content-Language', language)
        return response