from django.utils.translation import ugettext_lazy as _
from django.db import models
from django.db.models import F, TextChoices

from common.utils import lazyproperty
from common.db.models import BaseCreateUpdateModel
from assets.models import Asset, Node, FamilyMixin, Account
from orgs.mixins.models import OrgModelMixin


class UserAssetGrantedTreeNodeRelation(OrgModelMixin, FamilyMixin, BaseCreateUpdateModel):
    class NodeFrom(TextChoices):
        granted = 'granted', 'Direct node granted'
        child = 'child', 'Have children node'
        asset = 'asset', 'Direct asset granted'

    user = models.ForeignKey('users.User', db_constraint=False, on_delete=models.CASCADE)
    node = models.ForeignKey('assets.Node', default=None, on_delete=models.CASCADE,
                             db_constraint=False, null=False, related_name='granted_node_rels')
    node_key = models.CharField(max_length=64, verbose_name=_("Key"), db_index=True)
    node_parent_key = models.CharField(max_length=64, default='', verbose_name=_('Parent key'),
                                       db_index=True)
    node_from = models.CharField(choices=NodeFrom.choices, max_length=16, db_index=True)
    node_assets_amount = models.IntegerField(default=0)

    @property
    def key(self):
        return self.node_key

    @property
    def parent_key(self):
        return self.node_parent_key

    @classmethod
    def get_node_granted_status(cls, user, key):
        ancestor_keys = set(cls.get_node_ancestor_keys(key, with_self=True))
        ancestor_rel_nodes = cls.objects.filter(user=user, node_key__in=ancestor_keys)

        for rel_node in ancestor_rel_nodes:
            if rel_node.key == key:
                return rel_node.node_from, rel_node
            if rel_node.node_from == cls.NodeFrom.granted:
                return cls.NodeFrom.granted, None
        return '', None


class PermNode(Node):
    class Meta:
        proxy = True
        ordering = []

    # 特殊节点
    UNGROUPED_NODE_KEY = 'ungrouped'
    UNGROUPED_NODE_VALUE = _('Ungrouped')
    FAVORITE_NODE_KEY = 'favorite'
    FAVORITE_NODE_VALUE = _('Favorite')

    node_from = ''
    granted_assets_amount = 0

    annotate_granted_node_rel_fields = {
        'granted_assets_amount': F('granted_node_rels__node_assets_amount'),
        'node_from': F('granted_node_rels__node_from')
    }

    def use_granted_assets_amount(self):
        self.assets_amount = self.granted_assets_amount

    @classmethod
    def get_ungrouped_node(cls, assets_amount):
        return cls(
            id=cls.UNGROUPED_NODE_KEY,
            key=cls.UNGROUPED_NODE_KEY,
            value=cls.UNGROUPED_NODE_VALUE,
            assets_amount=assets_amount
        )

    @classmethod
    def get_favorite_node(cls, assets_amount):
        node = cls(
            id=cls.FAVORITE_NODE_KEY,
            key=cls.FAVORITE_NODE_KEY,
            value=cls.FAVORITE_NODE_VALUE,
        )
        node.assets_amount = assets_amount
        return node

    def get_granted_status(self, user):
        status, rel_node = UserAssetGrantedTreeNodeRelation.get_node_granted_status(user, self.key)
        self.node_from = status
        if rel_node:
            self.granted_assets_amount = rel_node.node_assets_amount
        return status

    def save(self):
        # 这是个只读 Model
        raise NotImplementedError


class PermedAsset(Asset):
    class Meta:
        proxy = True
        verbose_name = _('Permed asset')
        permissions = [
            ('view_myassets', _('Can view my assets')),
            ('view_userassets', _('Can view user assets')),
            ('view_usergroupassets', _('Can view usergroup assets')),
        ]


class PermedAccount(Account):
    @lazyproperty
    def actions(self):
        return 0

    class Meta:
        proxy = True
        verbose_name = _('Permed account')