from django.contrib.auth import get_user_model
from rest_framework import generics, filters
from apps.permissions.permissions import CompanyPermission
from rest_framework.exceptions import NotFound

from django.db.models.functions import Concat, Coalesce
from apps.permissions.models import UserCompanyRole
from apps.companies.models import Company
from apps.core.serializers.companyuserlist import CompanyUserSerializer
from utils.paginations import LimitOffsetPagination
from django.db.models import F, Value, Prefetch, Count


User = get_user_model()


class CompanyUsersView(generics.ListAPIView):
    """List all users in a specific company"""
    serializer_class = CompanyUserSerializer
    pagination_class = LimitOffsetPagination
    filter_backends = [filters.OrderingFilter, filters.SearchFilter]

    ordering_fields = ['full_name', 'email', 'profile__phone_number', 'companies_count']
    ordering = ['-created_at']

    search_fields = [
        'full_name',
        'email',
        'profile__phone_number',
    ]

    def get_permissions(self):
        return [CompanyPermission('view_users')]

    def get_company(self):
        """Get company based on user type and parameters."""
        user = self.request.user
        company_id = self.request.query_params.get('company_id')

        target_company_id = company_id or getattr(user.active_company, 'id', None)

        if not target_company_id:
            raise NotFound("No company id provided or user has no active company.")

        try:
            company = Company.objects.get(id=target_company_id)
        except Company.DoesNotExist:
            raise NotFound("Company not found.")

        return company

    def get_serializer_context(self):
        context = super().get_serializer_context()
        try:
            company = self.get_company()
        except NotFound:
            company = None
        context['company'] = company
        return context

    def get_queryset(self):
        """Get users from the specified company - assumes company is valid"""
        user = self.request.user
        company_id = self.request.query_params.get('company_id')

        if getattr(user, "user_type", None) == "super_admin" and company_id is None:
            return User.objects.select_related('profile').all()

        company = self.get_company()

        role_prefetch = Prefetch(
            'company_roles',
            queryset=UserCompanyRole.objects
            .select_related('role', 'company')
            .filter(is_active=True),
            to_attr='_cached_roles'
        )

        queryset = company.users.annotate(
            full_name=Concat(
                Coalesce(F('profile__first_name'), Value('')),
                Value(' '),
                Coalesce(F('profile__last_name'), Value('')),
            ),
            companies_count=Count('companies')
        ).select_related(
            'profile'
        ).prefetch_related(
            role_prefetch
        )

        if company and company.id:
            queryset = queryset.filter(companies=company)

        return queryset