import time
from collections import defaultdict

from django.conf import settings
from django.core.cache import cache

from users.models import User
from assets.models import Asset
from assets.utils import NodeAssetsUtil
from orgs.models import Organization
from orgs.utils import (
    current_org,
    tmp_to_org,
    tmp_to_root_org
)
from common.decorator import on_transaction_commit
from common.utils import get_logger
from common.utils.common import lazyproperty, timeit
from common.db.models import output_as_string

from perms.locks import UserGrantedTreeRebuildLock
from perms.models import (
    AssetPermission,
    UserAssetGrantedTreeNodeRelation,
    PermNode
)

from .permission import AssetPermissionUtil

logger = get_logger(__name__)

__all__ = [
    'UserPermTreeRefreshUtil',
    'UserPermTreeExpireUtil'
]


class _UserPermTreeCacheMixin:
    """ 缓存数据 users: {org_id, org_id }, 记录用户授权树已经构建完成的组织集合 """
    cache_key_template = 'perms.user.node_tree.built_orgs.user_id:{user_id}'

    def get_cache_key(self, user_id):
        return self.cache_key_template.format(user_id=user_id)

    @lazyproperty
    def client(self):
        return cache.client.get_client(write=True)


class UserPermTreeRefreshUtil(_UserPermTreeCacheMixin):
    """ 用户授权树刷新工具, 针对某一个用户授权树的刷新 """

    def __init__(self, user):
        self.user = user
        self.orgs = self.user.orgs.distinct()
        self.org_ids = [str(o.id) for o in self.orgs]

    @lazyproperty
    def cache_key_user(self):
        return self.get_cache_key(self.user.id)

    @timeit
    def refresh_if_need(self, force=False):
        self._clean_user_perm_tree_for_legacy_org()
        to_refresh_orgs = self.orgs if force else self._get_user_need_refresh_orgs()
        if not to_refresh_orgs:
            logger.info('Not have to refresh orgs')
            return
        with UserGrantedTreeRebuildLock(self.user.id):
            for org in to_refresh_orgs:
                self._rebuild_user_perm_tree_for_org(org)
        self._mark_user_orgs_refresh_finished(to_refresh_orgs)

    def _rebuild_user_perm_tree_for_org(self, org):
        with tmp_to_org(org):
            start = time.time()
            UserPermTreeBuildUtil(self.user).rebuild_user_perm_tree()
            end = time.time()
            logger.info(
                'Refresh user [{user}] org [{org}] perm tree, user {use_time:.2f}s'
                ''.format(user=self.user, org=org, use_time=end-start)
            )

    def _clean_user_perm_tree_for_legacy_org(self):
        with tmp_to_root_org():
            """ Clean user legacy org node relations """
            user_relations = UserAssetGrantedTreeNodeRelation.objects.filter(user=self.user)
            user_legacy_org_relations = user_relations.exclude(org_id__in=self.org_ids)
            user_legacy_org_relations.delete()

    def _get_user_need_refresh_orgs(self):
        cached_org_ids = self.client.smembers(self.cache_key_user)
        cached_org_ids = {oid.decode() for oid in cached_org_ids}
        to_refresh_org_ids = set(self.org_ids) - cached_org_ids
        to_refresh_orgs = Organization.objects.filter(id__in=to_refresh_org_ids)
        logger.info(f'Need to refresh orgs: {to_refresh_orgs}')
        return to_refresh_orgs

    def _mark_user_orgs_refresh_finished(self, orgs):
        org_ids = [str(org.id) for org in orgs]
        self.client.sadd(self.cache_key_user, *org_ids)


class UserPermTreeExpireUtil(_UserPermTreeCacheMixin):
    """ 用户授权树过期工具 """

    @lazyproperty
    def cache_key_all_user(self):
        return self.get_cache_key('*')

    def expire_perm_tree_for_nodes_assets(self, node_ids, asset_ids):
        node_perm_ids = AssetPermissionUtil().get_permissions_for_nodes(node_ids, flat=True)
        asset_perm_ids = AssetPermissionUtil().get_permissions_for_assets(asset_ids, flat=True)
        perm_ids = set(node_perm_ids) | set(asset_perm_ids)
        self.expire_perm_tree_for_perms(perm_ids)

    @tmp_to_root_org()
    def expire_perm_tree_for_perms(self, perm_ids):
        org_perm_ids = AssetPermission.objects.filter(id__in=perm_ids).values_list('org_id', 'id')
        org_perms_mapper = defaultdict(set)
        for org_id, perm_id in org_perm_ids:
            org_perms_mapper[org_id].add(perm_id)
        for org_id, perms_id in org_perms_mapper.items():
            user_ids = AssetPermission.get_all_users_for_perms(perm_ids, flat=True)
            self.expire_perm_tree_for_users_orgs(user_ids, [org_id])

    def expire_perm_tree_for_user_group(self, user_group):
        group_ids = [user_group.id]
        org_ids = [user_group.org_id]
        self.expire_perm_tree_for_user_groups_orgs(group_ids, org_ids)

    def expire_perm_tree_for_user_groups_orgs(self, group_ids, org_ids):
        user_ids = User.groups.through.objects.filter(usergroup_id__in=group_ids) \
            .values_list('user_id', flat=True).distinct()
        self.expire_perm_tree_for_users_orgs(user_ids, org_ids)

    @on_transaction_commit
    def expire_perm_tree_for_users_orgs(self, user_ids, org_ids):
        org_ids = [str(oid) for oid in org_ids]
        with self.client.pipeline() as p:
            for uid in user_ids:
                cache_key = self.get_cache_key(uid)
                p.srem(cache_key, *org_ids)
            p.execute()
        logger.info('Expire perm tree for users: [{}], orgs: [{}]'.format(user_ids, org_ids))

    def expire_perm_tree_for_all_user(self):
        keys = self.client.keys(self.cache_key_all_user)
        with self.client.pipeline() as p:
            for k in keys:
                p.delete(k)
            p.execute()
        logger.info('Expire all user perm tree')


class UserPermTreeBuildUtil(object):
    node_only_fields = ('id', 'key', 'parent_key', 'org_id')

    def __init__(self, user):
        self.user = user
        self.user_perm_ids = AssetPermissionUtil().get_permissions_for_user(self.user, flat=True)
        # {key: node}
        self._perm_nodes_key_node_mapper = {}

    def rebuild_user_perm_tree(self):
        self.clean_user_perm_tree()
        if not self.user_perm_ids:
            logger.info('User({}) not have permissions'.format(self.user))
            return
        self.compute_perm_nodes()
        self.compute_perm_nodes_asset_amount()
        self.create_mapping_nodes()

    def clean_user_perm_tree(self):
        UserAssetGrantedTreeNodeRelation.objects.filter(user=self.user).delete()

    def compute_perm_nodes(self):
        self._compute_perm_nodes_for_direct()
        self._compute_perm_nodes_for_direct_asset_if_need()
        self._compute_perm_nodes_for_ancestor()

    def compute_perm_nodes_asset_amount(self):
        """ 这里计算的是一个组织的授权树 """
        computed = self._only_compute_root_node_assets_amount_if_need()
        if computed:
            return

        nodekey_assetid_mapper = defaultdict(set)
        org_id = current_org.id
        for key in self.perm_node_keys_for_granted:
            asset_ids = PermNode.get_all_asset_ids_by_node_key(org_id, key)
            nodekey_assetid_mapper[key].update(asset_ids)

        for asset_id, node_id in self.direct_asset_id_node_id_pairs:
            node_key = self.perm_nodes_id_key_mapper.get(node_id)
            if not node_key:
                continue
            nodekey_assetid_mapper[node_key].add(asset_id)

        util = NodeAssetsUtil(self.perm_nodes, nodekey_assetid_mapper)
        util.generate()

        for node in self.perm_nodes:
            assets_amount = util.get_assets_amount(node.key)
            node.assets_amount = assets_amount

    def create_mapping_nodes(self):
        to_create = []
        for node in self.perm_nodes:
            relation = UserAssetGrantedTreeNodeRelation(
                user=self.user,
                node=node,
                node_key=node.key,
                node_parent_key=node.parent_key,
                node_from=node.node_from,
                node_assets_amount=node.assets_amount,
                org_id=node.org_id
            )
            to_create.append(relation)

        UserAssetGrantedTreeNodeRelation.objects.bulk_create(to_create)

    def _compute_perm_nodes_for_direct(self):
        """ 直接授权的节点（叶子节点）"""
        for node in self.direct_nodes:
            if self.has_any_ancestor_direct_permed(node):
                continue
            node.node_from = node.NodeFrom.granted
            self._perm_nodes_key_node_mapper[node.key] = node

    def _compute_perm_nodes_for_direct_asset_if_need(self):
        """ 直接授权的资产所在的节点（叶子节点）"""
        if settings.PERM_SINGLE_ASSET_TO_UNGROUP_NODE:
            return
        for node in self.direct_asset_nodes:
            if self.has_any_ancestor_direct_permed(node):
                continue
            if node.key in self._perm_nodes_key_node_mapper:
                continue
            node.node_from = node.NodeFrom.asset
            self._perm_nodes_key_node_mapper[node.key] = node

    def _compute_perm_nodes_for_ancestor(self):
        """ 直接授权节点 和 直接授权资产所在节点 的所有祖先节点 (构造完整树) """
        ancestor_keys = set()
        for node in self._perm_nodes_key_node_mapper.values():
            ancestor_keys.update(node.get_ancestor_keys())
        ancestor_keys -= set(self._perm_nodes_key_node_mapper.keys())

        ancestors = PermNode.objects.filter(key__in=ancestor_keys).only(*self.node_only_fields)
        for node in ancestors:
            node.node_from = node.NodeFrom.child
            self._perm_nodes_key_node_mapper[node.key] = node

    @lazyproperty
    def perm_node_keys_for_granted(self):
        keys = [
            key for key, node in self._perm_nodes_key_node_mapper.items()
            if node.node_from == node.NodeFrom.granted
        ]
        return keys

    @lazyproperty
    def perm_nodes_id_key_mapper(self):
        mapper = {
            node.id.hex: node.key
            for key, node in self._perm_nodes_key_node_mapper.items()
        }
        return mapper

    def _only_compute_root_node_assets_amount_if_need(self):
        if len(self.perm_nodes) != 1:
            return False
        root_node = self.perm_nodes[0]
        if not root_node.is_org_root():
            return False
        if root_node.node_from != root_node.NodeFrom.granted:
            return False
        root_node.granted_assets_amount = len(root_node.get_all_asset_ids())
        return True

    @lazyproperty
    def perm_nodes(self):
        """ 授权树的所有节点 """
        return list(self._perm_nodes_key_node_mapper.values())

    def has_any_ancestor_direct_permed(self, node):
        """ 任何一个祖先节点被直接授权 """
        return bool(set(node.get_ancestor_keys()) & set(self.direct_node_keys))

    @lazyproperty
    def direct_node_keys(self):
        """ 直接授权的节点 keys """
        return {n.key for n in self.direct_nodes}

    @lazyproperty
    def direct_nodes(self):
        """ 直接授权的节点 """
        node_ids = AssetPermission.nodes.through.objects \
            .filter(assetpermission_id__in=self.user_perm_ids) \
            .values_list('node_id', flat=True).distinct()
        nodes = PermNode.objects.filter(id__in=node_ids).only(*self.node_only_fields)
        return nodes

    @lazyproperty
    def direct_asset_nodes(self):
        """ 获取直接授权的资产所在的节点 """
        node_ids = [node_id for asset_id, node_id in self.direct_asset_id_node_id_pairs]
        nodes = PermNode.objects.filter(id__in=node_ids).distinct().only(*self.node_only_fields)
        return nodes

    @lazyproperty
    def direct_asset_id_node_id_pairs(self):
        """ 直接授权的资产 id 和 节点 id  """
        asset_node_pairs = Asset.nodes.through.objects \
            .filter(asset_id__in=self.direct_asset_ids) \
            .annotate(
                str_asset_id=output_as_string('asset_id'),
                str_node_id=output_as_string('node_id')
            ).values_list('str_asset_id', 'str_node_id')
        asset_node_pairs = list(asset_node_pairs)
        return asset_node_pairs

    @lazyproperty
    def direct_asset_ids(self):
        """ 直接授权的资产 ids """
        asset_ids = AssetPermission.assets.through.objects \
            .filter(assetpermission_id__in=self.user_perm_ids) \
            .values_list('asset_id', flat=True) \
            .distinct()
        return asset_ids