"""
runtime_store.py — LibBee v3.1

Fixes applied:
1. save() now uses atomic write-then-rename (os.replace) to prevent file
   corruption on crash or mid-write failure.
   os.replace is atomic on POSIX (Linux/macOS) and effectively atomic on
   Windows (same filesystem). This protects feedback.jsonl, metrics.json,
   and runtime_config.json from partial writes.
"""
import json
import os
import time
from pathlib import Path
from typing import Any, Dict, Optional


class JsonRuntimeStore:
    def __init__(self, path: Path, default: Optional[Dict[str, Any]] = None):
        self.path = Path(path)
        self.path.parent.mkdir(parents=True, exist_ok=True)
        self.default = default or {}

    def load(self) -> Dict[str, Any]:
        if not self.path.exists():
            return dict(self.default)
        try:
            return json.loads(self.path.read_text(encoding="utf-8"))
        except Exception:
            return dict(self.default)

    def save(self, data: Dict[str, Any]) -> None:
        """Atomically write data to disk using a temp file + os.replace."""
        tmp = self.path.with_suffix(".tmp")
        try:
            tmp.write_text(
                json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8"
            )
            os.replace(tmp, self.path)
        except Exception:
            try:
                tmp.unlink(missing_ok=True)
            except Exception:
                pass
            raise

    def update(self, **kwargs: Any) -> Dict[str, Any]:
        data = self.load()
        data.update(kwargs)
        data["updated_at"] = time.time()
        self.save(data)
        return data