refactor stats and user handlers

backend/handler/db_handler/db_users_handler.py

@@ -0,0 +1,46 @@
+from decorators.database import begin_session
+from handler.db_handler import DBHandler
+from models import Role, User
+from sqlalchemy import delete, select, update
+from sqlalchemy.orm import Session
+
+
+class DBUsersHandler(DBHandler):
+    @begin_session
+    def add_user(self, user: User, session: Session = None):
+        return session.merge(user)
+
+    @begin_session
+    def get_user_by_username(self, username: str, session: Session = None):
+        return session.scalars(
+            select(User).filter_by(username=username).limit(1)
+        ).first()
+
+    @begin_session
+    def get_user(self, id: int, session: Session = None):
+        return session.get(User, id)
+
+    @begin_session
+    def update_user(self, id: int, data: dict, session: Session = None):
+        session.execute(
+            update(User)
+            .where(User.id == id)
+            .values(**data)
+            .execution_options(synchronize_session="evaluate")
+        )
+
+    @begin_session
+    def delete_user(self, id: int, session: Session = None):
+        return session.execute(
+            delete(User)
+            .where(User.id == id)
+            .execution_options(synchronize_session="evaluate")
+        )
+
+    @begin_session
+    def get_users(self, session: Session = None):
+        return session.scalars(select(User)).all()
+
+    @begin_session
+    def get_admin_users(self, session: Session = None):
+        return session.scalars(select(User).filter_by(role=Role.ADMIN)).all()