"""
GLM 文件 ID 缓存（基于磁盘的简单 KV，sha256 → file_id，3天有效期）
"""
import hashlib
import json
import time
import threading
from pathlib import Path

_CACHE_FILE = Path(__file__).parent.parent / "uploads" / ".glm_file_cache.json"
_lock = threading.Lock()
_TTL = 3 * 24 * 3600  # 3天


def _load() -> dict:
    try:
        if _CACHE_FILE.exists():
            return json.loads(_CACHE_FILE.read_text(encoding="utf-8"))
    except Exception:
        pass
    return {}


def _save(data: dict) -> None:
    try:
        _CACHE_FILE.parent.mkdir(parents=True, exist_ok=True)
        _CACHE_FILE.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8")
    except Exception as e:
        print(f"[file_cache] 写入失败：{e}")


def sha256_of_file(file_path: Path) -> str:
    h = hashlib.sha256()
    with open(file_path, "rb") as f:
        for chunk in iter(lambda: f.read(65536), b""):
            h.update(chunk)
    return h.hexdigest()


def get(file_hash: str) -> dict | None:
    with _lock:
        data = _load()
        entry = data.get(file_hash)
        if not entry:
            return None
        if entry.get("expires_at", 0) <= time.time():
            data.pop(file_hash, None)
            _save(data)
            return None
        return entry


def set(file_hash: str, file_id: str) -> None:
    with _lock:
        data = _load()
        data[file_hash] = {"file_id": file_id, "expires_at": time.time() + _TTL}
        _save(data)


def delete(file_hash: str) -> None:
    with _lock:
        data = _load()
        data.pop(file_hash, None)
        _save(data)