Initial commit

services/thumbnail.py

@@ -0,0 +1,73 @@
+from __future__ import annotations
+import io
+import hashlib
+from pathlib import Path
+from typing import Tuple
+from fastapi import HTTPException
+
+ALLOWED_EXT = {"jpg", "jpeg", "png", "webp", "gif", "bmp", "tiff"}
+MAX_SOURCE_SIZE = 200 * 1024 * 1024
+CACHE_ROOT = Path('data/.thumb_cache')
+
+
+def is_image_filename(name: str) -> bool:
+    parts = name.rsplit('.', 1)
+    if len(parts) < 2:
+        return False
+    return parts[1].lower() in ALLOWED_EXT
+
+
+def _cache_key(adapter_id: int, rel: str, size: int, mtime: int, w: int, h: int, fit: str) -> str:
+    raw = f"{adapter_id}|{rel}|{size}|{mtime}|{w}x{h}|{fit}".encode()
+    return hashlib.sha1(raw).hexdigest()
+
+
+def _cache_path(key: str) -> Path:
+    sub = Path(key[:2]) / key[2:4]
+    return CACHE_ROOT / sub / f"{key}.webp"
+
+
+def _ensure_cache_dir(p: Path):
+    p.parent.mkdir(parents=True, exist_ok=True)
+
+
+def generate_thumb(data: bytes, w: int, h: int, fit: str) -> Tuple[bytes, str]:
+    from PIL import Image
+    im = Image.open(io.BytesIO(data))
+    if im.mode not in ("RGB", "RGBA"):
+        im = im.convert("RGBA" if im.mode in ("P", "LA") else "RGB")
+    if fit == 'cover':
+        im_ratio = im.width / im.height
+        target_ratio = w / h
+        if im_ratio > target_ratio:
+            new_h = h
+            new_w = int(h * im_ratio)
+        else:
+            new_w = w
+            new_h = int(w / im_ratio)
+        im = im.resize((new_w, new_h))
+        left = max(0, (im.width - w)//2)
+        top = max(0, (im.height - h)//2)
+        im = im.crop((left, top, left + w, top + h))
+    else:
+        im.thumbnail((w, h))
+    buf = io.BytesIO()
+    im.save(buf, 'WEBP', quality=80)
+    return buf.getvalue(), 'image/webp'
+
+
+async def get_or_create_thumb(adapter, adapter_id: int, root: str, rel: str, w: int, h: int, fit: str = 'cover'):
+    read_data = await adapter.read_file(root, rel)
+    if len(read_data) > MAX_SOURCE_SIZE:
+        raise HTTPException(404, detail="Image too large for thumbnail")
+    key = _cache_key(adapter_id, rel, len(read_data), 0, w, h, fit)
+    path = _cache_path(key)
+    if path.exists():
+        return path.read_bytes(), 'image/webp', key
+    _ensure_cache_dir(path)
+    try:
+        thumb_bytes, mime = generate_thumb(read_data, w, h, fit)
+    except Exception as e:
+        raise HTTPException(500, detail=f"Thumbnail generation failed: {e}")
+    path.write_bytes(thumb_bytes)
+    return thumb_bytes, mime, key