import logging
from django.apps import apps
from django.contrib.auth import get_user_model
from django.contrib.auth.models import Group

app_config = apps.get_containing_app_config(__package__)
logger = logging.getLogger(__name__)


def get_system_user():
    return get_user_model().objects.get_or_create(username='-system-')[0]


def get_ghost_user():
    return get_user_model().objects.get_or_create(username='-deleted-')[0]


def get_group_members(group_name, ignore_missing=False):
    users = []
    try:
        group = Group.objects.get(name=group_name)
        users.extend(group.user_set.all())
    except Group.DoesNotExist:
        if not ignore_missing:
            raise
    return users


def get_group_names_by_role(role):
    if role == 'publisher':
        sub_roles = ('publisher_print', 'publisher_web', 'publisher_facebook')
    elif role.startswith('publisher_'):
        sub_roles = (role, )
    elif role == 'manager':
        sub_roles = ('manager_super', 'manager_w', 'manager_s', 'manager_m', 'manager_k', 'manager_b')
    elif role == 'manager_super':
        sub_roles = (role, )
    elif role.startswith('manager_'):
        sub_roles = ('manager_super', role)
    else:
        sub_roles = (role, )

    group_names = []
    for sub_role in sub_roles:
        var_name = 'groups_{}'.format(sub_role)
        if hasattr(app_config.settings, var_name):
            group_names += getattr(app_config.settings, var_name)

    return list(set(group_names))


def get_users_by_role(role):
    users = []
    group_names = get_group_names_by_role(role)
    for group_name in group_names:
        users += get_group_members(group_name, ignore_missing=True)
    return list(set(users))


def has_role(user, role):
    group_names = get_group_names_by_role(role)
    if group_names and user.groups.filter(name__in=group_names).count():
        return True
    return False