1from __future__ import annotations
 2
 3import time
 4
 5from opentelemetry import trace
 6from opentelemetry.semconv._incubating.attributes.session_attributes import SESSION_ID
 7from plain.http import HttpMiddleware, Request, Response
 8from plain.runtime import settings
 9from plain.utils.cache import patch_vary_headers
10from plain.utils.http import http_date
11
12from .core import SessionStore
13from .requests import get_request_session, set_request_session
14
15__all__ = ["SessionMiddleware"]
16
17
18class SessionMiddleware(HttpMiddleware):
19    def before_request(self, request: Request) -> Response | None:
20        session_key = request.cookies.get(settings.SESSION_COOKIE_NAME)
21
22        session = SessionStore(session_key)
23        set_request_session(request, session)
24
25        if session.model_instance:
26            trace.get_current_span().set_attribute(
27                SESSION_ID, session.model_instance.id
28            )
29
30        return None
31
32    def after_response(self, request: Request, response: Response) -> Response:
33        """
34        If request.session was modified, or if the configuration is to save the
35        session every time, save the changes and set a session cookie or delete
36        the session cookie if the session has been emptied.
37        """
38        session = get_request_session(request)
39        accessed = session.accessed
40        modified = session.modified
41        empty = session.is_empty()
42
43        # First check if we need to delete this cookie.
44        # The session should be deleted only if the session is entirely empty.
45        if settings.SESSION_COOKIE_NAME in request.cookies and empty:
46            response.delete_cookie(
47                settings.SESSION_COOKIE_NAME,
48                path=settings.SESSION_COOKIE_PATH,
49                domain=settings.SESSION_COOKIE_DOMAIN,
50                samesite=settings.SESSION_COOKIE_SAMESITE,
51            )
52            patch_vary_headers(response, ["Cookie"])
53        else:
54            if accessed:
55                patch_vary_headers(response, ["Cookie"])
56            if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
57                if settings.SESSION_EXPIRE_AT_BROWSER_CLOSE:
58                    max_age = None
59                    expires = None
60                else:
61                    max_age = settings.SESSION_COOKIE_AGE
62                    expires_time = time.time() + max_age
63                    expires = http_date(expires_time)
64                # Save the session data and refresh the client cookie.
65                # Skip session save for 5xx responses.
66                if response.status_code < 500:
67                    session.save()
68                    # session_key must exist after save()
69                    assert session.session_key is not None, (
70                        "Session key should exist after save()"
71                    )
72                    response.set_cookie(
73                        settings.SESSION_COOKIE_NAME,
74                        session.session_key,
75                        max_age=max_age,
76                        expires=expires,
77                        domain=settings.SESSION_COOKIE_DOMAIN,
78                        path=settings.SESSION_COOKIE_PATH,
79                        secure=bool(settings.SESSION_COOKIE_SECURE),
80                        httponly=bool(settings.SESSION_COOKIE_HTTPONLY),
81                        samesite=settings.SESSION_COOKIE_SAMESITE,
82                    )
83        return response