"""domain_policy.yaml loader with lru_cache."""

from __future__ import annotations

import os
from functools import lru_cache
from pathlib import Path

import yaml

from policy.schema import DomainPolicy


DEFAULT_POLICY_FILENAME = "domain_policy.yaml"
POLICY_PATH_ENV = "POLICY_PATH"


def _resolve_path(path: str | None) -> Path:
    if path is not None:
        return Path(path)
    env_path = os.environ.get(POLICY_PATH_ENV)
    if env_path:
        return Path(env_path)

    # 검색 순서 (multi-env 호환):
    # 1. cwd / domain_policy.yaml               로컬 pytest (repo-root 실행)
    # 2. /app / domain_policy.yaml              container bind-mount 경로
    # 3. /app/../domain_policy.yaml             container: /app 의 parent
    # 4. <this>.parent.parent.parent / yaml     policy 패키지 기준 repo-root
    candidates = [
        Path.cwd() / DEFAULT_POLICY_FILENAME,
        Path("/app") / DEFAULT_POLICY_FILENAME,
        Path("/app").parent / DEFAULT_POLICY_FILENAME,
        Path(__file__).resolve().parent.parent.parent / DEFAULT_POLICY_FILENAME,
    ]
    for c in candidates:
        if c.is_file():
            return c
    # 찾지 못한 경우 첫 후보 반환 → 나중에 FileNotFoundError 로 명확히 실패
    return candidates[0]


@lru_cache(maxsize=8)
def _load_cached(resolved: str) -> DomainPolicy:
    text = Path(resolved).read_text(encoding="utf-8")
    raw = yaml.safe_load(text)
    return DomainPolicy.model_validate(raw)


def load_policy(path: str | None = None) -> DomainPolicy:
    """Load policy yaml and validate via pydantic.

    Cache key = resolved absolute path (문자열). 테스트에서 다른 path 주면 별도 캐시.
    """
    resolved = str(_resolve_path(path).resolve())
    return _load_cached(resolved)


def clear_cache() -> None:
    """테스트용 — 연속 호출 시 서로 다른 yaml 을 반영해야 할 때."""
    _load_cached.cache_clear()


def read_policy_bytes(path: str | None = None) -> bytes:
    """policy_version hash 계산용 — yaml 원본 바이트."""
    resolved = _resolve_path(path).resolve()
    return resolved.read_bytes()