from django.apps import apps

from ..utils.auth import has_perm
from ..utils.collection import Collection
from .models import Assignment


def get_permission_change_data(sender, permissions=None, **kwargs):
    """
    Yields all necessary collections if 'assignments.can_see' permission changes.
    """
    assignments_app = apps.get_app_config(app_label='assignments')
    for permission in permissions:
        # There could be only one 'assignment.can_see' and then we want to return data.
        if permission.content_type.app_label == assignments_app.label and permission.codename == 'can_see':
            yield from assignments_app.get_startup_elements()


def is_user_data_required(sender, request_user, user_data, **kwargs):
    """
    Returns True if request user can see assignments and user_data is required
    to be displayed as candidates (including poll options).
    """
    result = False
    if has_perm(request_user, 'assignments.can_see'):
        for assignment_collection_element in Collection(Assignment.get_collection_string()).element_generator():
            full_data = assignment_collection_element.get_full_data()
            for related_user in full_data['assignment_related_users']:
                if user_data['id'] == related_user['user_id']:
                    result = True
                    break
            else:
                for poll in full_data['polls']:
                    for option in poll['options']:
                        if user_data['id'] == option['candidate_id']:
                            result = True
                            break
                    else:
                        continue
                    break
                else:
                    continue
                break
            break
    return result