from mozilla_django_oidc.auth import OIDCAuthenticationBackend
import logging
from lofar.sas.tmss.tmss.tmssapp.models import ProjectRole
from django.contrib.auth.models import Group

logger = logging.getLogger(__name__)

class TMSSOIDCAuthenticationBackend(OIDCAuthenticationBackend):
    """
    A custom OIDCAuthenticationBackend, that allows us to perform extra actions when a user gets authenticated,
    most importantly we can assign the user's system and project roles according to the claims that we get from the
    identity provider.
    """

    def _set_user_project_roles_from_claims(self, user, claims):
        project_roles = []
        project_role_prefix = 'urn:mace:astron.nl:science:group:lofar:project:'
        project_role_map = {'contact': 'contact_author'}
        for entitlement in claims.get('eduperson_entitlement', []):
            try:
                if entitlement.startswith(project_role_prefix):
                    project_entitlement = entitlement.replace(project_role_prefix, '')
                    if 'role' in project_entitlement:
                        project_name, role_name = project_entitlement.split(':role=')
                        if role_name in project_role_map:
                            role_name = project_role_map[role_name]
                        if ProjectRole.objects.filter(value=role_name).count() > 0:
                            project_roles.append({'project': project_name, 'role': role_name})
                        else:
                            logger.error('could not handle entitlement=%s because no project role exists that matches the entitlement role=%s' % (entitlement, role_name))
                    else:
                        # we only care about explicit roles, 'general' membership of a project is not relevant to TMSS
                        pass
            except Exception as e:
                logger.error('could not handle entitlement=%s because of exception=%s' % (entitlement, e))
        user.project_roles = project_roles
        logger.info("### assigned project_roles=%s to user=%s" % (project_roles, user))
        user.save()

    def _set_user_system_roles_from_claims(self, user, claims):
        groups = []
        system_role_prefix = 'urn:mace:astron.nl:science:group:lofar:role='
        system_role_map = {'expert scientist': Group.objects.get(name='Scientist (Expert)')}   # usually, we can use the entitlement name as group name, but some groups have weird names and need to be translated
        for entitlement in claims.get('eduperson_entitlement', []):
            try:
                if entitlement.startswith(system_role_prefix):
                    role_name = entitlement.replace(system_role_prefix, '')
                    if role_name in system_role_map:
                        groups.append(system_role_map[role_name])
                    else:
                        role_name = role_name.replace('_', ' ')
                        if Group.objects.filter(name__iexact=role_name).count() > 0:
                            groups.append(Group.objects.filter(name__iexact=role_name).first())
                        else:
                            logger.error('could not handle entitlement=%s because no system role / group exists that matches the entitlement role=%s' % (entitlement, role_name))
            except Exception as e:
                logger.error('could not handle entitlement=%s because of exception=%s' % (entitlement, e))
        logger.info("### assigned groups=%s to user=%s" % (groups, user))
        user.groups.set(groups)
        user.save()

    def create_user(self, claims):
        user = super(TMSSOIDCAuthenticationBackend, self).create_user(claims)
        logger.info('### create user=%s claims=%s' % (user, claims))
        self._set_user_project_roles_from_claims(user, claims)
        self._set_user_system_roles_from_claims(user, claims)
        return user

    def update_user(self, user, claims):
        logger.info('### update user=%s claims=%s' % (user, claims))
        self._set_user_project_roles_from_claims(user, claims)
        self._set_user_system_roles_from_claims(user, claims)
        return user