from django.db import transaction
from django.db.models import Count
from rest_framework import filters
from rest_framework import status
from rest_framework import viewsets
from rest_framework.decorators import action
from rest_framework.exceptions import APIException
from rest_framework.response import Response

from apps.authorization.api.v1.serializers import (
    RoleSerializer,
    PermissionSerializer,
    UserRelationSerializer,
    PageSerializer
)
from apps.authorization.exception import AdminRoleDeleteException
from apps.authorization.models import (
    Role,
    Permissions,
    UserRelations,
    Page
)
from apps.core.api import BaseViewSet
from apps.core.exceptions import ConflictException
from apps.core.mixins.search_mixin import DynamicSearchMixin
from apps.core.mixins.soft_delete_mixin import SoftDeleteMixin
from common.helpers import get_organization_by_user


class RoleViewSet(BaseViewSet, SoftDeleteMixin, viewsets.ModelViewSet):
    """ Crud Operations For User Roles """

    queryset = Role.objects.all()
    serializer_class = RoleSerializer
    filter_backends = [filters.SearchFilter]
    search_fields = ['role_name', 'type__name']

    def list(self, request, *args, **kwargs):
        """ all roles """

        role = self.paginate_queryset(self.get_queryset().order_by('-modify_date'))
        if role is not None:  # noqa
            serializer = self.get_serializer(role, many=True)
            return self.get_paginated_response(serializer.data)

    def destroy(self, request, pk=None, *args, **kwargs):
        """ soft delete of role except Admin """

        role = self.get_object()
        if role.type.key == 'ADM':
            raise AdminRoleDeleteException()
        role.soft_delete()
        return Response(status=status.HTTP_200_OK)


class PageViewSet(SoftDeleteMixin, viewsets.ModelViewSet):
    """ add website pages to system to set permission on it """

    queryset = Page.objects.all()
    serializer_class = PageSerializer
    filter_backends = [filters.SearchFilter]
    search_fields = ['name', 'code']

    def list(self, request, *args, **kwargs):
        """ all pages """

        page = self.paginate_queryset(self.filter_queryset(self.queryset.order_by('-modify_date')))
        if page is not None:  # noqa
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)

    @action(
        methods=['delete'],
        detail=True,
        url_name='delete',
        url_path='delete',
        name='delete'
    )
    @transaction.atomic
    def delete(self, request, pk=None):
        """ Full delete of page & permissions of page object """
        try:
            page = self.queryset.get(id=pk)
            permissions = Permissions.objects.filter(page=page)
            permissions.delete()
            page.delete()
            return Response(status=status.HTTP_200_OK)
        except APIException as e:
            return Response(e, status=status.HTTP_204_NO_CONTENT)


class PermissionViewSet(SoftDeleteMixin, viewsets.ModelViewSet):
    """ Crud Operations for Permissions """

    queryset = Permissions.objects.all()
    serializer_class = PermissionSerializer
    filter_backends = [filters.SearchFilter]
    search_fields = ['page__name', 'name']

    def list(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset().order_by('-modify_date'))  # noqa

        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

    def create(self, request, *args, **kwargs):
        if self.queryset.filter(name=request.data['name'], page_id=request.data['page']).exists():
            raise ConflictException('a permission with this page exists.')
        serializer = self.serializer_class(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_200_OK)
        else:
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(
        methods=['get'],
        detail=False,
        url_name='connectionless_permissions',
        url_path='connectionless_permissions',
        name='connectionless_permissions'
    )
    @transaction.atomic
    def connectionless_permissions(self, request, *args, **kwargs):
        """ get all permissions that are not assigned to any user relation """

        permissions = Permissions.objects.annotate(
            user_relation_num=Count('userrelations'),  # noqa
            role_num=Count('role'),
        ).filter(user_relation_num=0, role_num=0)  # noqa

        page = self.paginate_queryset(self.filter_queryset(permissions))
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(permissions, many=True)
        return Response(serializer.data)


class UserRelationViewSet(BaseViewSet, SoftDeleteMixin, viewsets.ModelViewSet, DynamicSearchMixin):
    """ Crud Operations for User Relations """

    queryset = UserRelations.objects.select_related('organization', 'role', 'user')
    serializer_class = UserRelationSerializer
    filter_backends = [filters.SearchFilter]
    search_fields = [
        'user__username',
        'user__mobile',
        'user__phone',
        'user__first_name',
        'user__last_name',
        'user__national_code',
        'user__province__name',
        'user__city__name',
        'user__unit_name',
        'user__unit_national_id',
    ]

    def list(self, request, *args, **kwargs):
        role_param = self.request.query_params.get('role')  # noqa

        org = get_organization_by_user(request.user)

        queryset = self.get_queryset(
            visibility_by_org_scope=True
        ) if org.free_visibility_by_scope else self.get_queryset()

        if role_param != '':
            queryset = queryset.filter(role_id=int(role_param))
        else:
            queryset = queryset.order_by('-create_date')

        queryset = self.filter_queryset(queryset)  # noqa

        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)