from mozilla_django_oidc.auth import OIDCAuthenticationBackend
from django.contrib.auth.models import Group

# Keycloak group name → Django group name mapping.
# Keycloak may send group paths with a leading slash (e.g. "/LabHelper Administrators");
# these are stripped before comparison.
KEYCLOAK_GROUP_MAP = {
    'LabHelper Administrators': 'LabHelper Administrators',
    'LabHelper Staff': 'LabHelper Staff',
    'LabHelper Viewers': 'LabHelper Viewers',
}

# Members of these groups receive is_staff=True (Django admin access)
STAFF_GROUPS = {'LabHelper Administrators'}


class KeycloakOIDCBackend(OIDCAuthenticationBackend):
    """OIDC backend that maps Keycloak groups to Django groups on every login."""

    def get_username(self, claims):
        return claims.get('preferred_username') or super().get_username(claims)

    def create_user(self, claims):
        user = super().create_user(claims)
        self._sync_from_claims(user, claims)
        return user

    def update_user(self, user, claims):
        user = super().update_user(user, claims)
        self._sync_from_claims(user, claims)
        return user

    def _sync_from_claims(self, user, claims):
        """Sync user attributes and group memberships from Keycloak token claims."""
        user.first_name = claims.get('given_name', user.first_name)
        user.last_name = claims.get('family_name', user.last_name)

        # Keycloak sends group paths like "/LabHelper Administrators"; normalise them.
        raw_groups = claims.get('groups', [])
        keycloak_groups = {g.lstrip('/') for g in raw_groups}

        user.is_staff = bool(keycloak_groups & STAFF_GROUPS)
        user.save()

        # Add/remove the user from each managed Django group to match Keycloak.
        for kc_group, django_group_name in KEYCLOAK_GROUP_MAP.items():
            try:
                group = Group.objects.get(name=django_group_name)
            except Group.DoesNotExist:
                continue
            if kc_group in keycloak_groups:
                user.groups.add(group)
            else:
                user.groups.remove(group)