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


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