from dataclasses import dataclass, field
from pathlib import Path

import yaml


@dataclass(slots=True)
class InstanceSpec:
    port: int
    overlays: list[str] = field(default_factory=list)
    arguments: list[str] = field(default_factory=list)
    config: list[str] = field(default_factory=list)


def load_spec(path: Path) -> InstanceSpec:
    raw = yaml.safe_load(path.read_text()) or {}
    return InstanceSpec(
        port=int(raw["port"]),
        overlays=[str(item) for item in raw.get("overlays", [])],
        arguments=[str(item) for item in raw.get("arguments", [])],
        config=[str(item) for item in raw.get("config", [])],
    )