from typing import Generator, Type

from ..core.exceptions import ProjectorException
from ..utils.projector import ProjectorElement
from .models import Item


class ItemListSlide(ProjectorElement):
    """
    Slide definitions for Item model.

    This is only for item list slides.

    Set 'id' to None to get a list slide of all root items. Set 'id' to an
    integer to get a list slide of the children of the metioned item.

    Additionally set 'tree' to True to get also children of children.
    """

    name = "agenda/item-list"

    def check_data(self):
        pk = self.config_entry.get("id")
        if pk is not None:
            # Children slide.
            if not Item.objects.filter(pk=pk).exists():
                raise ProjectorException("Item does not exist.")


class ListOfSpeakersSlide(ProjectorElement):
    """
    Slide definitions for Item model.
    This is only for list of speakers slide. You have to set 'id'.
    """

    name = "agenda/list-of-speakers"

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

    def update_data(self):
        return {"agenda_item_id": self.config_entry.get("id")}


class CurrentListOfSpeakersSlide(ProjectorElement):
    """
    Slide for the current list of speakers.
    """

    name = "agenda/current-list-of-speakers"


def get_projector_elements() -> Generator[Type[ProjectorElement], None, None]:
    yield ItemListSlide
    yield ListOfSpeakersSlide
    yield CurrentListOfSpeakersSlide