# -*- coding: utf-8 -*-
#
from collections import defaultdict
from functools import partial

from django.db.models.signals import m2m_changed
from django.db.models.signals import post_save, pre_delete
from django.dispatch import receiver

from orgs.utils import tmp_to_org
from .models import Organization, OrganizationMember
from .hands import set_current_org, Node, get_current_org
from perms.models import (AssetPermission, ApplicationPermission)
from users.models import UserGroup, User
from applications.models import Application
from assets.models import Asset, AdminUser, SystemUser, Domain, Gateway
from common.const.signals import PRE_REMOVE, POST_REMOVE, POST_PREFIX
from .caches import OrgResourceStatisticsCache


@receiver(post_save, sender=Organization)
def on_org_create_or_update(sender, instance=None, created=False, **kwargs):
    if instance:
        old_org = get_current_org()
        set_current_org(instance)
        node_root = Node.org_root()
        if node_root.value != instance.name:
            node_root.value = instance.name
            node_root.save()
        set_current_org(old_org)

    if instance and not created:
        instance.expire_cache()


def _remove_users(model, users, org):
    with tmp_to_org(org):
        if not isinstance(users, (tuple, list, set)):
            users = (users, )

        m2m_model = model.users.through
        reverse = model.users.reverse
        if reverse:
            m2m_field_name = model.users.field.m2m_reverse_field_name()
        else:
            m2m_field_name = model.users.field.m2m_field_name()
        relations = m2m_model.objects.filter(**{
            'user__in': users,
            f'{m2m_field_name}__org_id': org.id
        })

        object_id_users_id_map = defaultdict(set)

        m2m_field_attr_name = f'{m2m_field_name}_id'
        for relation in relations:
            object_id = getattr(relation, m2m_field_attr_name)
            object_id_users_id_map[object_id].add(relation.user_id)

        objects = model.objects.filter(id__in=object_id_users_id_map.keys())
        send_m2m_change_signal = partial(
            m2m_changed.send,
            sender=m2m_model, reverse=reverse, model=User, using=model.objects.db
        )

        for obj in objects:
            send_m2m_change_signal(
                instance=obj,
                pk_set=object_id_users_id_map[obj.id],
                action=PRE_REMOVE
            )

        relations.delete()

        for obj in objects:
            send_m2m_change_signal(
                instance=obj,
                pk_set=object_id_users_id_map[obj.id],
                action=POST_REMOVE
            )


def _clear_users_from_org(org, users):
    """
    清理用户在该组织下的相关数据
    """
    if not users:
        return

    models = (AssetPermission, ApplicationPermission, UserGroup)

    for m in models:
        _remove_users(m, users, org)


@receiver(m2m_changed, sender=OrganizationMember)
def on_org_user_changed(action, instance, reverse, pk_set, **kwargs):
    if action == 'post_remove':
        if reverse:
            user = instance
            org_pk_set = pk_set

            orgs = Organization.objects.filter(id__in=org_pk_set)
            for org in orgs:
                if not org.members.filter(id=user.id).exists():
                    _clear_users_from_org(org, user)
        else:
            org = instance
            user_pk_set = pk_set

            leaved_users = set(pk_set) - set(org.members.filter(id__in=user_pk_set).values_list('id', flat=True))
            _clear_users_from_org(org, leaved_users)


# 缓存相关
# -----------------------------------------------------

def refresh_user_amount_on_user_create_or_delete(user_id):
    orgs = Organization.objects.filter(m2m_org_members__user_id=user_id).distinct()
    for org in orgs:
        org_cache = OrgResourceStatisticsCache(org)
        org_cache.refresh_async('users_amount')


@receiver(post_save, sender=User)
def on_user_create_refresh_cache(sender, instance, created, **kwargs):
    if created:
        refresh_user_amount_on_user_create_or_delete(instance.id)


@receiver(pre_delete, sender=User)
def on_user_delete_refresh_cache(sender, instance, **kwargs):
    refresh_user_amount_on_user_create_or_delete(instance.id)


@receiver(m2m_changed, sender=OrganizationMember)
def on_org_user_changed_refresh_cache(sender, action, instance, reverse, pk_set, **kwargs):
    if not action.startswith(POST_PREFIX):
        return

    if reverse:
        orgs = Organization.objects.filter(id__in=pk_set)
    else:
        orgs = [instance]

    for org in orgs:
        org_cache = OrgResourceStatisticsCache(org)
        org_cache.refresh_async('users_amount')


class OrgResourceStatisticsRefreshUtil:
    model_cache_field_mapper = {
        ApplicationPermission: 'app_perms_amount',
        AssetPermission: 'asset_perms_amount',
        Application: 'applications_amount',
        Gateway: 'gateways_amount',
        Domain: 'domains_amount',
        SystemUser: 'system_users_amount',
        AdminUser: 'admin_users_amount',
        Node: 'nodes_amount',
        Asset: 'assets_amount',
        UserGroup: 'groups_amount',
    }

    @classmethod
    def refresh_if_need(cls, instance):
        cache_field_name = cls.model_cache_field_mapper.get(type(instance))
        if cache_field_name:
            org_cache = OrgResourceStatisticsCache(instance.org)
            org_cache.refresh_async(cache_field_name)


@receiver(post_save)
def on_post_save_refresh_org_resource_statistics_cache(sender, instance, created, **kwargs):
    if created:
        OrgResourceStatisticsRefreshUtil.refresh_if_need(instance)


@receiver(pre_delete)
def on_pre_delete_refresh_org_resource_statistics_cache(sender, instance, **kwargs):
    OrgResourceStatisticsRefreshUtil.refresh_if_need(instance)