from django.contrib.auth import get_user_model
from django.core.exceptions import PermissionDenied
from django.utils.translation import ugettext as _, ugettext_lazy

from misago.search import SearchProvider

from .serializers import UserSerializer


HEAD_RESULTS = 8
TAIL_RESULTS = 8


class SearchUsers(SearchProvider):
    name = ugettext_lazy("Users")
    url = 'users'

    def allow_search(self):
        if not self.request.user.acl['can_search_users']:
            raise PermissionDenied(
                _("You don't have permission to search users."))

    def search(self, query, page=1):
        if query:
            results = search_users(
                search_disabled=self.request.user.is_staff,
                username=query
            )
        else:
            results = []

        return {
            'results': UserSerializer(results, many=True).data,
            'count': len(results)
        }


def search_users(**filters):
    User = get_user_model()
    queryset = User.objects.order_by('slug').select_related(
        'rank', 'ban_cache', 'online_tracker')

    if not filters.get('search_disabled', False):
        queryset = queryset.filter(is_active=True)

    username = filters.get('username').lower()

    results = []

    # lets grab head and tail results:
    results += list(queryset.filter(slug__startswith=username)[:HEAD_RESULTS])
    results += list(queryset.filter(
        slug__contains=username
    ).exclude(pk__in=[r.pk for r in results])[:TAIL_RESULTS])

    return results