"""Shared image upload utilities used by both the edit and serve servers."""
from __future__ import annotations

from pathlib import Path

ALLOWED_IMAGE_TYPES: frozenset[str] = frozenset({
    "image/jpeg",
    "image/png",
    "image/webp",
    "image/gif",
})
MAX_IMAGE_BYTES: int = 10 * 1024 * 1024  # 10 MB


def unique_image_name(directory: Path, filename: str) -> str:
    """Return a filename that does not collide with existing files in directory."""
    stem, suffix = Path(filename).stem, Path(filename).suffix
    candidate = filename
    counter = 1
    while (directory / candidate).exists():
        candidate = f"{stem}_{counter}{suffix}"
        counter += 1
    return candidate