from typing import Generator, Type

from ..core.exceptions import ProjectorException
from ..utils.projector import ProjectorElement
from .models import Assignment, AssignmentPoll


class AssignmentSlide(ProjectorElement):
    """
    Slide definitions for Assignment model.

    You can send a poll id to get a poll slide.
    """

    name = "assignments/assignment"

    def check_data(self):
        if not Assignment.objects.filter(pk=self.config_entry.get("id")).exists():
            raise ProjectorException("Election does not exist.")
        poll_id = self.config_entry.get("poll")
        if poll_id:
            # Poll slide.
            try:
                poll = AssignmentPoll.objects.get(pk=poll_id)
            except AssignmentPoll.DoesNotExist:
                raise ProjectorException("Poll does not exist.")
            if poll.assignment_id != self.config_entry.get("id"):
                raise ProjectorException(
                    "Assignment id and poll do not belong together."
                )

    def update_data(self):
        data = None
        try:
            assignment = Assignment.objects.get(pk=self.config_entry.get("id"))
        except Assignment.DoesNotExist:
            # Assignment does not exist, so just do nothing.
            pass
        else:
            data = {"agenda_item_id": assignment.agenda_item_id}
        return data


def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
    yield AssignmentSlide