"""Game-agnostic file operations."""
from __future__ import annotations

import re
from pathlib import Path


def get_server_dir(server_id: int) -> Path:
    """Return the absolute directory path for a server's data."""
    from config import settings
    base = Path(settings.servers_dir).resolve()
    return base / str(server_id)


def ensure_server_dirs(server_id: int, layout: list[str] | None = None) -> None:
    """
    Create servers/{id}/ and any subdirectories from adapter layout.
    layout example: ["server", "battleye", "mpmissions"]
    """
    server_dir = get_server_dir(server_id)
    server_dir.mkdir(parents=True, exist_ok=True)
    if layout:
        for subdir in layout:
            (server_dir / subdir).mkdir(parents=True, exist_ok=True)


def safe_delete_file(path: Path) -> bool:
    """Delete a file if it exists. Returns True if deleted."""
    try:
        path.unlink(missing_ok=True)
        return True
    except OSError:
        return False


def sanitize_filename(filename: str) -> str:
    """
    Sanitize a filename for safe disk storage.

    Rules:
    - Strip path separators (/ \\ and ..)
    - Allow only alphanumeric, dots, hyphens, underscores, @ signs
    - Collapse consecutive dots (prevent ../ tricks)
    - Truncate to 255 characters
    - Raise ValueError if the result is empty
    """
    # Take only the basename — strip any directory components
    filename = filename.replace("\\", "/").split("/")[-1]

    # Remove null bytes and control characters
    filename = re.sub(r"[\x00-\x1f\x7f]", "", filename)

    # Allow only safe characters: alphanum, dot, hyphen, underscore, @
    filename = re.sub(r"[^\w.\-@]", "_", filename)

    # Collapse consecutive dots to prevent tricks like ".../.."
    filename = re.sub(r"\.{2,}", ".", filename)

    # Truncate
    filename = filename[:255]

    if not filename or filename in (".", ".."):
        raise ValueError(f"Filename '{filename}' is not safe for storage")

    return filename