✨(project) Django boilerplate

This commit introduces a boilerplate inspired by https://github.com/numerique-gouv/impress.
The code has been cleaned to remove unnecessary Impress logic and dependencies.

Changes made:
- Removed Minio, WebRTC, and create bucket from the stack.
- Removed the Next.js frontend (it will be replaced by Vite).
- Cleaned up impress-specific backend logics.

The whole stack remains functional:
- All tests pass.
- Linter checks pass.
- Agent Connexion sources are already set-up.

Why clear out the code?

To adhere to the KISS principle, we aim to maintain a minimalist codebase. Cloning Impress
allowed us to quickly inherit its code quality tools and deployment configurations for staging,
pre-production, and production environments.

What’s broken?
- The tsclient is not functional anymore.
- Some make commands need to be fixed.
- Helm sources are outdated.
- Naming across the project sources are inconsistent (impress, visio, etc.)
- CI is not configured properly.

This list might be incomplete. Let's grind it.

src/backend/core/authentication/views.py

@@ -0,0 +1,137 @@
+"""Authentication Views for the People core app."""
+
+from urllib.parse import urlencode
+
+from django.contrib import auth
+from django.core.exceptions import SuspiciousOperation
+from django.http import HttpResponseRedirect
+from django.urls import reverse
+from django.utils import crypto
+
+from mozilla_django_oidc.utils import (
+    absolutify,
+)
+from mozilla_django_oidc.views import (
+    OIDCLogoutView as MozillaOIDCOIDCLogoutView,
+)
+
+
+class OIDCLogoutView(MozillaOIDCOIDCLogoutView):
+    """Custom logout view for handling OpenID Connect (OIDC) logout flow.
+
+    Adds support for handling logout callbacks from the identity provider (OP)
+    by initiating the logout flow if the user has an active session.
+
+    The Django session is retained during the logout process to persist the 'state' OIDC parameter.
+    This parameter is crucial for maintaining the integrity of the logout flow between this call
+    and the subsequent callback.
+    """
+
+    @staticmethod
+    def persist_state(request, state):
+        """Persist the given 'state' parameter in the session's 'oidc_states' dictionary
+
+        This method is used to store the OIDC state parameter in the session, according to the
+        structure expected by Mozilla Django OIDC's 'add_state_and_verifier_and_nonce_to_session'
+        utility function.
+        """
+
+        if "oidc_states" not in request.session or not isinstance(
+            request.session["oidc_states"], dict
+        ):
+            request.session["oidc_states"] = {}
+
+        request.session["oidc_states"][state] = {}
+        request.session.save()
+
+    def construct_oidc_logout_url(self, request):
+        """Create the redirect URL for interfacing with the OIDC provider.
+
+        Retrieves the necessary parameters from the session and constructs the URL
+        required to initiate logout with the OpenID Connect provider.
+
+        If no ID token is found in the session, the logout flow will not be initiated,
+        and the method will return the default redirect URL.
+
+        The 'state' parameter is generated randomly and persisted in the session to ensure
+        its integrity during the subsequent callback.
+        """
+
+        oidc_logout_endpoint = self.get_settings("OIDC_OP_LOGOUT_ENDPOINT")
+
+        if not oidc_logout_endpoint:
+            return self.redirect_url
+
+        reverse_url = reverse("oidc_logout_callback")
+        id_token = request.session.get("oidc_id_token", None)
+
+        if not id_token:
+            return self.redirect_url
+
+        query = {
+            "id_token_hint": id_token,
+            "state": crypto.get_random_string(self.get_settings("OIDC_STATE_SIZE", 32)),
+            "post_logout_redirect_uri": absolutify(request, reverse_url),
+        }
+
+        self.persist_state(request, query["state"])
+
+        return f"{oidc_logout_endpoint}?{urlencode(query)}"
+
+    def post(self, request):
+        """Handle user logout.
+
+        If the user is not authenticated, redirects to the default logout URL.
+        Otherwise, constructs the OIDC logout URL and redirects the user to start
+        the logout process.
+
+        If the user is redirected to the default logout URL, ensure her Django session
+        is terminated.
+        """
+
+        logout_url = self.redirect_url
+
+        if request.user.is_authenticated:
+            logout_url = self.construct_oidc_logout_url(request)
+
+        # If the user is not redirected to the OIDC provider, ensure logout
+        if logout_url == self.redirect_url:
+            auth.logout(request)
+
+        return HttpResponseRedirect(logout_url)
+
+
+class OIDCLogoutCallbackView(MozillaOIDCOIDCLogoutView):
+    """Custom view for handling the logout callback from the OpenID Connect (OIDC) provider.
+
+    Handles the callback after logout from the identity provider (OP).
+    Verifies the state parameter and performs necessary logout actions.
+
+    The Django session is maintained during the logout process to ensure the integrity
+    of the logout flow initiated in the previous step.
+    """
+
+    http_method_names = ["get"]
+
+    def get(self, request):
+        """Handle the logout callback.
+
+        If the user is not authenticated, redirects to the default logout URL.
+        Otherwise, verifies the state parameter and performs necessary logout actions.
+        """
+
+        if not request.user.is_authenticated:
+            return HttpResponseRedirect(self.redirect_url)
+
+        state = request.GET.get("state")
+
+        if state not in request.session.get("oidc_states", {}):
+            msg = "OIDC callback state not found in session `oidc_states`!"
+            raise SuspiciousOperation(msg)
+
+        del request.session["oidc_states"][state]
+        request.session.save()
+
+        auth.logout(request)
+
+        return HttpResponseRedirect(self.redirect_url)