from typing import Generator, Type

from ..core.exceptions import ProjectorException
from ..utils.projector import ProjectorElement
from .models import Motion, MotionBlock


class MotionSlide(ProjectorElement):
    """
    Slide definitions for Motion model.
    """
    name = 'motions/motion'

    def check_data(self):
        if not Motion.objects.filter(pk=self.config_entry.get('id')).exists():
            raise ProjectorException('Motion does not exist.')

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


class MotionBlockSlide(ProjectorElement):
    """
    Slide definitions for a block of motions (MotionBlock model).
    """
    name = 'motions/motion-block'

    def check_data(self):
        if not MotionBlock.objects.filter(pk=self.config_entry.get('id')).exists():
            raise ProjectorException('MotionBlock does not exist.')

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


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