"""Thumbnail generation and on-disk caching (~/.cache/SaraFem/Thumbnails)."""

import hashlib
from pathlib import Path

from PIL import Image

from Core import ThumbnailCacheDir

ImageExtensions = {".png", ".jpg", ".jpeg", ".gif", ".bmp", ".webp"}


def IsThumbnailable(EntryPath: Path) -> bool:
    return EntryPath.suffix.lower() in ImageExtensions


def GetThumbnail(EntryPath: Path, Size: tuple[int, int] = (128, 128)) -> Path | None:
    """Return a cached thumbnail path for `EntryPath`, generating it if stale or missing."""
    if not IsThumbnailable(EntryPath):
        return None

    Stat = EntryPath.stat()
    CacheKey = hashlib.sha256(f"{EntryPath}:{Stat.st_mtime}:{Size}".encode()).hexdigest()
    CachePath = ThumbnailCacheDir / f"{CacheKey}.png"

    if CachePath.exists():
        return CachePath

    ThumbnailCacheDir.mkdir(parents=True, exist_ok=True)
    try:
        with Image.open(EntryPath) as Img:
            Img.thumbnail(Size)
            Img.convert("RGB").save(CachePath, "PNG")
    except Exception:
        return None

    return CachePath