✨(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- Helm sources are outdated.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/api/__init__.py

@@ -0,0 +1,39 @@
+"""Impress core API endpoints"""
+from django.conf import settings
+from django.core.exceptions import ValidationError
+
+from rest_framework import exceptions as drf_exceptions
+from rest_framework import views as drf_views
+from rest_framework.decorators import api_view
+from rest_framework.response import Response
+
+
+def exception_handler(exc, context):
+    """Handle Django ValidationError as an accepted exception.
+
+    For the parameters, see ``exception_handler``
+    This code comes from twidi's gist:
+    https://gist.github.com/twidi/9d55486c36b6a51bdcb05ce3a763e79f
+    """
+    if isinstance(exc, ValidationError):
+        if hasattr(exc, "message_dict"):
+            detail = exc.message_dict
+        elif hasattr(exc, "message"):
+            detail = exc.message
+        elif hasattr(exc, "messages"):
+            detail = exc.messages
+
+        exc = drf_exceptions.ValidationError(detail=detail)
+
+    return drf_views.exception_handler(exc, context)
+
+
+# pylint: disable=unused-argument
+@api_view(["GET"])
+def get_frontend_configuration(request):
+    """Returns the frontend configuration dict as configured in settings."""
+    frontend_configuration = {
+        "LANGUAGE_CODE": settings.LANGUAGE_CODE,
+    }
+    frontend_configuration.update(settings.FRONTEND_CONFIGURATION)
+    return Response(frontend_configuration)

src/backend/core/api/permissions.py

@@ -0,0 +1,36 @@
+"""Permission handlers for the impress core app."""
+from rest_framework import permissions
+
+ACTION_FOR_METHOD_TO_PERMISSION = {
+    "versions_detail": {"DELETE": "versions_destroy", "GET": "versions_retrieve"}
+}
+
+
+class IsAuthenticated(permissions.BasePermission):
+    """
+    Allows access only to authenticated users. Alternative method checking the presence
+    of the auth token to avoid hitting the database.
+    """
+
+    def has_permission(self, request, view):
+        return bool(request.auth) or request.user.is_authenticated
+
+
+class IsAuthenticatedOrSafe(IsAuthenticated):
+    """Allows access to authenticated users (or anonymous users but only on safe methods)."""
+
+    def has_permission(self, request, view):
+        if request.method in permissions.SAFE_METHODS:
+            return True
+        return super().has_permission(request, view)
+
+
+class IsSelf(IsAuthenticated):
+    """
+    Allows access only to authenticated users. Alternative method checking the presence
+    of the auth token to avoid hitting the database.
+    """
+
+    def has_object_permission(self, request, view, obj):
+        """Write permissions are only allowed to the user itself."""
+        return obj == request.user

src/backend/core/api/serializers.py

@@ -0,0 +1,13 @@
+"""Client serializers for the impress core app."""
+from rest_framework import serializers
+
+from core import models
+
+
+class UserSerializer(serializers.ModelSerializer):
+    """Serialize users."""
+
+    class Meta:
+        model = models.User
+        fields = ["id", "email"]
+        read_only_fields = ["id", "email"]

src/backend/core/api/viewsets.py

@@ -0,0 +1,142 @@
+"""API endpoints"""
+from rest_framework import (
+    decorators,
+    mixins,
+    pagination,
+    viewsets,
+)
+from rest_framework import (
+    response as drf_response,
+)
+
+from core import models
+
+from . import permissions, serializers
+
+# pylint: disable=too-many-ancestors
+
+
+class NestedGenericViewSet(viewsets.GenericViewSet):
+    """
+    A generic Viewset aims to be used in a nested route context.
+    e.g: `/api/v1.0/resource_1/<resource_1_pk>/resource_2/<resource_2_pk>/`
+
+    It allows to define all url kwargs and lookup fields to perform the lookup.
+    """
+
+    lookup_fields: list[str] = ["pk"]
+    lookup_url_kwargs: list[str] = []
+
+    def __getattribute__(self, item):
+        """
+        This method is overridden to allow to get the last lookup field or lookup url kwarg
+        when accessing the `lookup_field` or `lookup_url_kwarg` attribute. This is useful
+        to keep compatibility with all methods used by the parent class `GenericViewSet`.
+        """
+        if item in ["lookup_field", "lookup_url_kwarg"]:
+            return getattr(self, item + "s", [None])[-1]
+
+        return super().__getattribute__(item)
+
+    def get_queryset(self):
+        """
+        Get the list of items for this view.
+
+        `lookup_fields` attribute is enumerated here to perform the nested lookup.
+        """
+        queryset = super().get_queryset()
+
+        # The last lookup field is removed to perform the nested lookup as it corresponds
+        # to the object pk, it is used within get_object method.
+        lookup_url_kwargs = (
+            self.lookup_url_kwargs[:-1]
+            if self.lookup_url_kwargs
+            else self.lookup_fields[:-1]
+        )
+
+        filter_kwargs = {}
+        for index, lookup_url_kwarg in enumerate(lookup_url_kwargs):
+            if lookup_url_kwarg not in self.kwargs:
+                raise KeyError(
+                    f"Expected view {self.__class__.__name__} to be called with a URL "
+                    f'keyword argument named "{lookup_url_kwarg}". Fix your URL conf, or '
+                    "set the `.lookup_fields` attribute on the view correctly."
+                )
+
+            filter_kwargs.update(
+                {self.lookup_fields[index]: self.kwargs[lookup_url_kwarg]}
+            )
+
+        return queryset.filter(**filter_kwargs)
+
+
+class SerializerPerActionMixin:
+    """
+    A mixin to allow to define serializer classes for each action.
+
+    This mixin is useful to avoid to define a serializer class for each action in the
+    `get_serializer_class` method.
+    """
+
+    serializer_classes: dict[str, type] = {}
+    default_serializer_class: type = None
+
+    def get_serializer_class(self):
+        """
+        Return the serializer class to use depending on the action.
+        """
+        return self.serializer_classes.get(self.action, self.default_serializer_class)
+
+
+class Pagination(pagination.PageNumberPagination):
+    """Pagination to display no more than 100 objects per page sorted by creation date."""
+
+    ordering = "-created_on"
+    max_page_size = 100
+    page_size_query_param = "page_size"
+
+
+class UserViewSet(
+    mixins.UpdateModelMixin, viewsets.GenericViewSet, mixins.ListModelMixin
+):
+    """User ViewSet"""
+
+    permission_classes = [permissions.IsSelf]
+    queryset = models.User.objects.all()
+    serializer_class = serializers.UserSerializer
+
+    def get_queryset(self):
+        """
+        Limit listed users by querying the email field with a trigram similarity
+        search if a query is provided.
+        Limit listed users by excluding users already in the document if a document_id
+        is provided.
+        """
+        queryset = self.queryset
+
+        if self.action == "list":
+            # Exclude all users already in the given document
+            if document_id := self.request.GET.get("document_id", ""):
+                queryset = queryset.exclude(documentaccess__document_id=document_id)
+
+            # Filter users by email similarity
+            if query := self.request.GET.get("q", ""):
+                queryset = queryset.filter(email__trigram_word_similar=query)
+
+        return queryset
+
+    @decorators.action(
+        detail=False,
+        methods=["get"],
+        url_name="me",
+        url_path="me",
+        permission_classes=[permissions.IsAuthenticated],
+    )
+    def get_me(self, request):
+        """
+        Return information on currently logged user
+        """
+        context = {"request": request}
+        return drf_response.Response(
+            self.serializer_class(request.user, context=context).data
+        )