from __future__ import annotations

import os
import tempfile
from typing import Optional


def atomic_write(path: str, data: bytes, mode: int = 0o644) -> None:
    """
    Atomically write bytes to path by writing to a temp file in the same dir and then replacing.
    """
    directory = os.path.dirname(path)
    os.makedirs(directory, exist_ok=True)
    fd, tmp_path = tempfile.mkstemp(prefix=".tmp-", dir=directory)
    try:
        with os.fdopen(fd, "wb") as tmp_file:
            tmp_file.write(data)
        os.chmod(tmp_path, mode)
        os.replace(tmp_path, path)
    finally:
        try:
            if os.path.exists(tmp_path):
                os.remove(tmp_path)
        except Exception:
            pass


def ensure_unique_path(path: str) -> str:
    """
    If path exists, append -2, -3, ... before extension to avoid collision.
    """
    if not os.path.exists(path):
        return path
    base, ext = os.path.splitext(path)
    i = 2
    while True:
        candidate = f"{base}-{i}{ext}"
        if not os.path.exists(candidate):
            return candidate
        i += 1