"""Rubric loader — YAML → Pydantic Rubric (SLICE-01, D-039).

Loads a competency rubric by skill name from the `rubrics/` directory, validates
it against the Pydantic schema, and caches the parsed result in-memory for the
lifetime of the process. Used by the scoring engine (SLICE-03) and the path
engine (SLICE-05).
"""

from __future__ import annotations

from pathlib import Path
from threading import Lock
from typing import Dict

import yaml

from server.mastery.rubric_schema import Rubric, ValidationError

_DEFAULT_RUBRICS_DIR = Path(__file__).resolve().parent.parent.parent / "rubrics"

_cache: Dict[str, Rubric] = {}
_cache_lock = Lock()


def load_rubric(skill: str, rubrics_dir: Path | None = None) -> Rubric:
    """Load and validate a rubric by skill name.

    Args:
        skill: e.g. 'customer_service' (the YAML filename stem under rubrics/).
        rubrics_dir: override the rubrics directory (default: repo /rubrics).

    Returns:
        A validated Rubric object. Cached in-memory per skill.

    Raises:
        FileNotFoundError: if the YAML file doesn't exist.
        ValidationError: if the YAML fails schema validation (typed Pydantic error).
    """
    with _cache_lock:
        cached = _cache.get(skill)
        if cached is not None:
            return cached

    base = rubrics_dir or _DEFAULT_RUBRICS_DIR
    path = base / f"{skill}.yaml"
    if not path.exists():
        raise FileNotFoundError(f"Rubric YAML not found: {skill} in {base}")

    with path.open("r", encoding="utf-8") as f:
        raw = yaml.safe_load(f)

    rubric = Rubric.model_validate(raw)

    with _cache_lock:
        _cache[skill] = rubric
    return rubric


def clear_cache() -> None:
    """Clear the in-memory rubric cache (test helper)."""
    with _cache_lock:
        _cache.clear()


__all__ = ["load_rubric", "clear_cache", "ValidationError"]