From a689d23bc86b37d8d24d426d066c59e682afe1d6 Mon Sep 17 00:00:00 2001
From: Alexey Kudelko <flexivanov237@gmail.com>
Date: Wed, 17 Jul 2024 13:02:01 +0300
Subject: [PATCH] added endpoint to switch leader

---
 projects/exceptions.py |  9 +++++++++
 projects/urls.py       |  2 ++
 projects/views.py      | 36 +++++++++++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 projects/exceptions.py

diff --git a/projects/exceptions.py b/projects/exceptions.py
new file mode 100644
index 00000000..cc1306ce
--- /dev/null
+++ b/projects/exceptions.py
@@ -0,0 +1,9 @@
+from rest_framework import status
+from rest_framework.exceptions import APIException
+from django.utils.translation import gettext_lazy as _
+
+
+class CollaboratorDoesNotExist(APIException):
+    status_code = status.HTTP_422_UNPROCESSABLE_ENTITY
+    default_detail = _("Not found.")
+    default_code = "not_found"
diff --git a/projects/urls.py b/projects/urls.py
index f19ab6b7..cc785712 100644
--- a/projects/urls.py
+++ b/projects/urls.py
@@ -15,6 +15,7 @@
     ProjectSubscribe,
     ProjectUnsubscribe,
     ProjectSubscribers,
+    SwitchLeaderRole,
 )
 
 app_name = "projects"
@@ -30,6 +31,7 @@
     path("<int:project_pk>/news/<int:pk>/set_viewed/", NewsDetailSetViewed.as_view()),
     path("<int:project_pk>/news/<int:pk>/set_liked/", NewsDetailSetLiked.as_view()),
     path("<int:pk>/collaborators/", ProjectCollaborators.as_view()),
+    path("<int:pk>/collaborators/switch-leader/", SwitchLeaderRole.as_view()),
     path("<int:pk>/", ProjectDetail.as_view()),
     path("<int:pk>/recommended_users", ProjectRecommendedUsers.as_view()),
     path("count/", ProjectCountView.as_view()),
diff --git a/projects/views.py b/projects/views.py
index 530252d9..50f9a36f 100644
--- a/projects/views.py
+++ b/projects/views.py
@@ -1,6 +1,7 @@
 import logging
 
 from django.contrib.auth import get_user_model
+from django.core.exceptions import ObjectDoesNotExist
 from django.db.models import Q
 from django_filters import rest_framework as filters
 from drf_yasg import openapi
@@ -15,6 +16,7 @@
 from core.serializers import SetLikedSerializer
 from core.services import add_view, set_like
 from partner_programs.models import PartnerProgram, PartnerProgramUserProfile
+from projects.exceptions import CollaboratorDoesNotExist
 from projects.filters import ProjectFilter
 from projects.constants import VERBOSE_STEPS
 from projects.helpers import (
@@ -22,7 +24,7 @@
     check_related_fields_update,
     update_partner_program,
 )
-from projects.models import Project, Achievement, ProjectNews
+from projects.models import Project, Achievement, ProjectNews, Collaborator
 from projects.pagination import ProjectNewsPagination, ProjectsPagination
 from projects.permissions import (
     IsProjectLeaderOrReadOnlyForNonDrafts,
@@ -461,3 +463,35 @@ def post(self, request, project_pk):
         return Response(
             {"detail": "Subscriber was successfully removed"}, status=status.HTTP_200_OK
         )
+
+
+class SwitchLeaderRole(generics.GenericAPIView):
+    permission_classes = [IsProjectLeader]
+    queryset = Project.objects.all().select_related("leader")
+
+    def _get_new_leader(self, user_id: int, project: Project) -> Collaborator:
+        try:
+            return Collaborator.objects.select_related("user").get(
+                user_id=user_id, project=project
+            )
+        except ObjectDoesNotExist:
+            raise CollaboratorDoesNotExist(
+                f"""Collaborator with user_id: {user_id} does not exist. Either user_id is not correct, or project_id
+                is not correct, or try adding this user to a project (as collaborator) before making them a leader. """
+            )
+
+    def patch(self, request, pk: int):
+        project = self.get_object()
+
+        new_leader_id = int(request.data["new_leader_id"])
+        new_leader = self._get_new_leader(new_leader_id, project)
+
+        if project.leader.id == new_leader_id:
+            return Response(
+                {"error": "User is already a leader of a project"},
+                status=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            )
+
+        project.leader = new_leader.user
+        project.save()
+        return Response(status=204)