from django.conf import settings
from urllib.parse import urlparse, urlunparse
import logging

from django.shortcuts import redirect
from django.utils import timezone, translation

logger = logging.getLogger(__name__)
logging.basicConfig(level=logging.INFO)

def switch_language(request):
    """
    Switches the current language context for the user based on a request parameter, modifies the URL path
    accordingly, and updates session and cookies with the new language preference.

    :param request: The HTTP request object containing information about the user request, including
                    the desired language to switch to and the referring URL.
                    - "GET" dictionary is accessed to retrieve the desired language parameter.
                    - "META" dictionary is used to extract the referring URL via "HTTP_REFERER".

    :return: A redirect response object pointing to the modified URL with the updated language
             preference, if the requested language is valid. Otherwise, redirects to the default URL.
    """
    language = request.GET.get("language", "en")
    referer = request.META.get("HTTP_REFERER", "/")
    parsed_url = urlparse(referer)
    path_parts = parsed_url.path.split("/")

    if path_parts[1] in dict(settings.LANGUAGES):
        path_parts.pop(1)

    new_path = "/".join(path_parts)
    new_url = urlunparse(
        (
            parsed_url.scheme,
            parsed_url.netloc,
            new_path,
            parsed_url.params,
            parsed_url.query,
            parsed_url.fragment,
        )
    )

    if language in dict(settings.LANGUAGES):
        logger.debug(f"Switching language to: {language}")
        response = redirect(new_url)
        response.set_cookie(settings.LANGUAGE_COOKIE_NAME, language)
        translation.activate(language)
        request.session[settings.LANGUAGE_COOKIE_NAME] = language
        logger.debug(
            f"Language switched to: {language}, Session: {request.session[settings.LANGUAGE_COOKIE_NAME]}"
        )
        return response
    else:
        logger.warning(f"Invalid language code: {language}")
        return redirect("/")