# Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later

from django.http import HttpResponseRedirect

from urllib.parse import urlencode, parse_qs, urlsplit, urlunsplit


class SmoothNavigationMiddleware(object):
    """Keep `?back=` queryset parameter on POST requests."""
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):  # noqa D102
        response = self.get_response(request)

        if isinstance(response, HttpResponseRedirect):
            back = request.GET.get('back')
            if back:
                _, _, back_path, _, _ = urlsplit(back)
                scheme, netloc, path, query_string, fragment = urlsplit(response['location'])
                query_params = parse_qs(query_string)

                if path == back_path:
                    query_params.pop('back', None)
                elif 'back' not in query_params:
                    query_params['back'] = [back]

                new_query_string = urlencode(query_params, doseq=True)
                response['location'] = urlunsplit((scheme, netloc, path, new_query_string, fragment))

        return response


class TurbolinksMiddleware(object):
    """
    Send the `Turbolinks-Location` header in response to a visit that was redirected,
    and Turbolinks will replace the browser's topmost history entry.
    """

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

    def __call__(self, request):
        response = self.get_response(request)

        is_turbolinks = request.META.get('HTTP_TURBOLINKS_REFERRER')
        is_response_redirect = response.has_header('Location')

        if is_turbolinks:
            if is_response_redirect:
                location = response['Location']
                prev_location = request.session.pop('_turbolinks_redirect_to', None)
                if prev_location is not None:
                    # relative subsequent redirect
                    if location.startswith('.'):
                        location = prev_location.split('?')[0] + location
                request.session['_turbolinks_redirect_to'] = location
            else:
                if request.session.get('_turbolinks_redirect_to'):
                    location = request.session.pop('_turbolinks_redirect_to')
                    response['Turbolinks-Location'] = location
        return response