from __future__ import annotations

import json
from pathlib import Path


def default_known_issues_path(script_file: str) -> Path:
    return Path(script_file).resolve().parent.parent / "known_issues" / "runtime_known_issues.json"


def load_known_issue_ids(script_file: str, category: str, configured_path: str | None) -> tuple[Path | None, set[str]]:
    if configured_path:
        path = Path(configured_path).resolve()
    else:
        candidate = default_known_issues_path(script_file)
        path = candidate if candidate.is_file() else None

    if path is None:
        return None, set()

    if not path.is_file():
        raise FileNotFoundError(f"known issues file not found: {path}")

    data = json.loads(path.read_text(encoding="utf-8"))
    raw_values = data.get(category, [])
    if not isinstance(raw_values, list):
        raise ValueError(f"known issues category '{category}' must be a list")
    return path, {str(value) for value in raw_values}


def classify_issue_ids(observed: set[str], known: set[str]) -> tuple[set[str], set[str], set[str]]:
    known_observed = observed & known
    unexpected = observed - known
    stale = known - observed
    return known_observed, unexpected, stale