from collections.abc import Iterable
import dataclasses
from typing import Self


class Shift: ...

@dataclasses.dataclass
class Skill:
    id: int


@dataclasses.dataclass
class Operator1:
    id: int
    shift: Shift
    skills: list[Skill]

    def __post_init__(self) -> None:
        # All operators carry their own ID as a skill so we can lock jobs to
        # specific people
        self.skills.append(Skill(self.id))

    @classmethod
    def new(
        cls,
        id: int,
        shift: Shift,
        skills: Skill | Iterable[Skill] | None = None,
    ) -> Self:
        if __debug__:
            if isinstance(skills, Iterable):
                if not all(
                    isinstance(item, Skill)  # type: ignore
                    for item in skills
                ):
                    raise ValueError("Invalid skill type included in list of skills")
        return cls(
            id,
            shift,
            (
                [skills]
                if isinstance(skills, Skill) else
                list(skills or [])
            ),
        )


@dataclasses.dataclass
class Operator2:
    id: int
    shift: Shift
    skills: list[Skill]

    def __post_init__(self) -> None:
        self.skills.append(Skill(self.id))

    @classmethod
    def from_single(
        cls,
        id: int,
        shift: Shift,
        skills: Skill | None = None,
    ) -> Self:
        return cls(
            id,
            shift,
            [] if skills is None else [skills],
        )