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"""Handle the management of resource/user groups."""
from uuid import UUID, uuid4
from typing import Sequence, Iterable, NamedTuple
from flask import g
from pymonad.maybe import Just, Maybe, Nothing
from gn3.auth import db
from gn3.auth.authentication.users import User
from gn3.auth.authentication.checks import authenticated_p
from .checks import authorised_p
from .privileges import Privilege
from .roles import Role, create_role
from .exceptions import AuthorisationError
class Group(NamedTuple):
"""Class representing a group."""
group_id: UUID
group_name: str
class GroupRole(NamedTuple):
"""Class representing a role tied/belonging to a group."""
group_role_id: UUID
group: Group
role: Role
class MembershipError(AuthorisationError):
"""Raised when there is an error with a user's membership to a group."""
def __init__(self, user: User, groups: Sequence[Group]):
"""Initialise the `MembershipError` exception object."""
groups_str = ", ".join(group.group_name for group in groups)
error_message = (
f"User '{user.name} ({user.email})' is a member of {len(groups)} "
f"groups ({groups_str})")
super().__init__(f"{type(self).__name__}: {error_message}.")
def user_membership(conn: db.DbConnection, user: User) -> Sequence[Group]:
"""Returns all the groups that a member belongs to"""
query = (
"SELECT groups.group_id, group_name FROM group_users INNER JOIN groups "
"ON group_users.group_id=groups.group_id "
"WHERE group_users.user_id=?")
with db.cursor(conn) as cursor:
cursor.execute(query, (str(user.user_id),))
groups = tuple(Group(row[0], row[1]) for row in cursor.fetchall())
return groups
@authenticated_p
@authorised_p(("create-group",), error_message="Failed to create group.")
def create_group(conn: db.DbConnection, group_name: str,
group_leader: User) -> Group:
"""Create a group"""
group = Group(uuid4(), group_name)
user_groups = user_membership(conn, group_leader)
if len(user_groups) > 0:
raise MembershipError(group_leader, user_groups)
with db.cursor(conn) as cursor:
cursor.execute(
"INSERT INTO groups(group_id, group_name) VALUES (?, ?)",
(str(group.group_id), group_name))
cursor.execute(
"INSERT INTO group_users VALUES (?, ?)",
(str(group.group_id), str(group_leader.user_id)))
return group
@authenticated_p
@authorised_p(("create-role",), error_message="Could not create the group role")
def create_group_role(
conn: db.DbConnection, group: Group, role_name: str,
privileges: Iterable[Privilege]) -> GroupRole:
"""Create a role attached to a group."""
with db.cursor(conn) as cursor:
group_role_id = uuid4()
role = create_role(cursor, role_name, privileges)
cursor.execute(
("INSERT INTO group_roles(group_role_id, group_id, role_id) "
"VALUES(?, ?, ?)"),
(str(group_role_id), str(group.group_id), str(role.role_id)))
return GroupRole(group_role_id, group, role)
@authenticated_p
def authenticated_user_group(conn) -> Maybe:
"""
Returns the currently authenticated user's group.
Look into returning a Maybe object.
"""
user = g.user
with db.cursor(conn) as cursor:
cursor.execute(
("SELECT groups.group_id, groups.group_name FROM group_users "
"INNER JOIN groups ON group_users.group_id=groups.group_id "
"WHERE group_users.user_id = ?"),
(str(user.user_id),))
groups = tuple(Group(UUID(row[0]), row[1]) for row in cursor.fetchall())
if len(groups) > 1:
raise MembershipError(user, groups)
if len(groups) == 1:
return Just(groups[0])
return Nothing
def user_group(cursor: db.DbCursor, user: User) -> Maybe:
"""Returns the given user's group"""
cursor.execute(
("SELECT groups.group_id, groups.group_name FROM group_users "
"INNER JOIN groups ON group_users.group_id=groups.group_id "
"WHERE group_users.user_id = ?"),
(str(user.user_id),))
groups = tuple(Group(UUID(row[0]), row[1]) for row in cursor.fetchall())
if len(groups) > 1:
raise MembershipError(user, groups)
if len(groups) == 1:
return Just(groups[0])
return Nothing
def is_group_leader(cursor: db.DbCursor, user: User, group: Group):
"""Check whether the given `user` is the leader of `group`."""
ugroup = user_group(cursor, user).maybe(False, lambda val: val) # type: ignore[misc]
if not group:
# User cannot be a group leader if not a member of ANY group
return False
if not ugroup == group:
# User cannot be a group leader if not a member of THIS group
return False
cursor.execute(
("SELECT roles.role_name FROM user_roles LEFT JOIN roles "
"ON user_roles.role_id = roles.role_id WHERE user_id = ?"),
(str(user.user_id),))
role_names = tuple(row[0] for row in cursor.fetchall())
return "group-leader" in role_names
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