wip introduce add-in endpoints and views

src/backend/core/addons/views.py

@@ -0,0 +1,57 @@
+"""Add-ons views."""
+
+from django.conf import settings
+from django.core.exceptions import SuspiciousOperation
+from django.shortcuts import redirect, render
+from django.utils.translation import gettext_lazy as _
+from django.views.decorators.http import require_http_methods
+
+from core.addons.service import SessionState, TokenExchangeService
+
+
+def render_error(request, message, status=400):
+    """Render simple error page."""
+    return render(request, "addons/error.html", {"message": message}, status=status)
+
+
+@require_http_methods(["GET"])
+def transit_page(request):
+    """Initialize authentication flow for add-on session."""
+
+    session_id = request.GET.get("session_id")
+
+    if not session_id:
+        return render_error(request, _("Session ID is required."), status=400)
+
+    data = TokenExchangeService().get_session(session_id)
+
+    if not data:
+        return render_error(request, _("Session not found or expired."), status=404)
+
+    if data.get("state") != SessionState.PENDING:
+        return render_error(request, _("Invalid session state."), status=400)
+
+    request.session[settings.ADDONS_SESSION_KEY_AUTH] = session_id
+
+    return_to = request.build_absolute_uri("/addons/redirect")
+    return redirect(f"/api/{settings.API_VERSION}/authenticate/?returnTo={return_to}")
+
+
+@require_http_methods(["GET"])
+def redirect_page(request):
+    """Complete authentication and close the popup window."""
+
+    if not request.user.is_authenticated:
+        return render_error(request, _("Authentication required."), status=401)
+
+    session_id = request.session.pop(settings.ADDONS_SESSION_KEY_AUTH, None)
+
+    if not session_id:
+        return render_error(request, _("No active session found."), status=404)
+
+    try:
+        TokenExchangeService().set_access_token(request.user, session_id)
+    except SuspiciousOperation:
+        return render_error(request, _("Invalid or expired session."), status=400)
+
+    return render(request, "addons/redirect_success.html")