Add support for bookmark thumbnails (#721)

* Preview Image

* fix tests

* add test

* download preview image

* relative path

* gst

* details view

* fix tests

* Improve preview image styles

* Remove preview image URL from model

* Revert form changes

* update tests

* make it work in uwsgi

---------

Co-authored-by: Sascha Ißbrücker <sascha.issbruecker@gmail.com>

bookmarks/services/preview_image_loader.py

@@ -0,0 +1,46 @@
+import logging
+import mimetypes
+import os.path
+import hashlib
+from pathlib import Path
+
+import requests
+from django.conf import settings
+from bookmarks.services import website_loader
+
+logger = logging.getLogger(__name__)
+
+
+def _ensure_preview_folder():
+    Path(settings.LD_PREVIEW_FOLDER).mkdir(parents=True, exist_ok=True)
+
+
+def _url_to_filename(preview_image: str) -> str:
+    return hashlib.md5(preview_image.encode()).hexdigest()
+
+
+def _get_image_path(preview_image_file: str) -> Path:
+    return Path(os.path.join(settings.LD_PREVIEW_FOLDER, preview_image_file))
+
+
+def load_preview_image(url: str) -> str | None:
+    _ensure_preview_folder()
+
+    metadata = website_loader.load_website_metadata(url)
+    if not metadata.preview_image:
+        logger.debug(f"Could not find preview image in metadata: {url}")
+        return None
+
+    logger.debug(f"Loading preview image: {metadata.preview_image}")
+    with requests.get(metadata.preview_image, stream=True) as response:
+        content_type = response.headers["Content-Type"]
+        preview_image_hash = _url_to_filename(url)
+        file_extension = mimetypes.guess_extension(content_type)
+        preview_image_file = f"{preview_image_hash}{file_extension}"
+        preview_image_path = _get_image_path(preview_image_file)
+        with open(preview_image_path, "wb") as file:
+            for chunk in response.iter_content(chunk_size=8192):
+                file.write(chunk)
+    logger.debug(f"Saved preview image as: {preview_image_path}")
+
+    return preview_image_file