"""registry.yaml 读写。"""

from __future__ import annotations

import hashlib
from pathlib import Path
from typing import Any

from skiff import yaml_io
from skiff.paths import REGISTRY_FILE


def load_registry(path: Path | None = None) -> dict[str, dict[str, Any]]:
    path = path or REGISTRY_FILE
    if not path.is_file():
        return {}
    data = yaml_io.safe_load(path.read_text(encoding="utf-8")) or {}
    if not isinstance(data, dict):
        raise SystemExit(f"registry 格式错误: {path}")
    return {k: v for k, v in data.items() if isinstance(v, dict) and not k.startswith("#")}


def save_registry(data: dict[str, dict[str, Any]], path: Path | None = None) -> None:
    path = path or REGISTRY_FILE
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(yaml_io.safe_dump(data, allow_unicode=True, sort_keys=False), encoding="utf-8")


def external_repo_path(entry: dict[str, Any]) -> Path:
    """Return the shared checkout path for a repo/ref pair."""
    from skiff.paths import EXTERNALS_DIR

    repo = str(entry.get("repo", ""))
    ref = str(entry.get("ref", "main"))
    digest = hashlib.sha256(f"{repo}\0{ref}".encode()).hexdigest()[:16]
    return EXTERNALS_DIR / "_repos" / digest


def external_checkout_path(name: str, entry: dict[str, Any]) -> Path:
    """Prefer an existing pre-shared-cache checkout for compatibility."""
    from skiff.paths import EXTERNALS_DIR

    legacy = EXTERNALS_DIR / name
    return legacy if legacy.is_dir() else external_repo_path(entry)


def external_skill_path(name: str, entry: dict[str, Any] | None = None) -> Path:
    entry = entry or load_registry().get(name, {})
    subpath = entry.get("path", ".") or "."
    checkout = external_checkout_path(name, entry).resolve()
    skill_path = (checkout / subpath).resolve()
    try:
        skill_path.relative_to(checkout)
    except ValueError as exc:
        raise SystemExit(
            f"registry 条目 {name!r} 的 path 超出外部仓库: {subpath!r}"
        ) from exc
    return skill_path