import time

from django.contrib.sessions.middleware import SessionMiddleware
from django.conf import settings
from django.utils.cache import patch_vary_headers
from django.utils.http import cookie_date


class AdminSessionMiddleware(SessionMiddleware):
    def get_cookie_name(self, request):
        default_key = settings.SESSION_COOKIE_NAME
        if request.path.startswith('/%s/' % settings.ADMIN_URL):
            return 'admin_%s' % default_key
        return default_key

    def process_request(self, request):
        session_key = request.COOKIES.get(self.get_cookie_name(request), None)
        request.session = self.SessionStore(session_key)

    def process_response(self, request, response):
        """
        If request.session was modified, or if the configuration is to save the
        session every time, save the changes and set a session cookie or delete
        the session cookie if the session has been emptied.
        """
        cookie_name = self.get_cookie_name(request)
        try:
            accessed = request.session.accessed
            modified = request.session.modified
            empty = request.session.is_empty()
        except AttributeError:
            pass
        else:
            # First check if we need to delete this cookie.
            # The session should be deleted only if the session is entirely
            # empty
            if cookie_name in request.COOKIES and empty:
                response.delete_cookie(cookie_name,
                                       domain=settings.SESSION_COOKIE_DOMAIN)
            else:
                if accessed:
                    patch_vary_headers(response, ('Cookie',))
                if modified or settings.SESSION_SAVE_EVERY_REQUEST:
                    if request.session.get_expire_at_browser_close():
                        max_age = None
                        expires = None
                    else:
                        max_age = request.session.get_expiry_age()
                        expires_time = time.time() + max_age
                        expires = cookie_date(expires_time)
                    # Save the session data and refresh the client cookie.
                    # Skip session save for 500 responses, refs #3881.
                    if response.status_code != 500:
                        request.session.save()
                        response.set_cookie(
                            cookie_name,
                            request.session.session_key,
                            max_age=max_age,
                            expires=expires,
                            domain=settings.SESSION_COOKIE_DOMAIN,
                            path=settings.SESSION_COOKIE_PATH,
                            secure=settings.SESSION_COOKIE_SECURE or None,
                            httponly=settings.SESSION_COOKIE_HTTPONLY or None
                        )
        return response