attachments: add basic resizing

Needs GIF support.

litecord/blueprints/attachments.py

@@ -17,15 +17,46 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
 
-from quart import Blueprint, send_file, current_app as app
+from pathlib import Path
+
+from quart import Blueprint, send_file, current_app as app, request
+from PIL import Image
 
 bp = Blueprint('attachments', __name__)
+ATTACHMENTS = Path.cwd() / 'attachments'
+
+
+async def _resize(image, attach_id: str, ext: str,
+                  width: int, height: int) -> str:
+    """Resize an image."""
+    # TODO: gif support
+
+    # check if we have it on the folder
+    resized_path = ATTACHMENTS / f'{attach_id}_{width}_{height}.{ext}'
+
+    # keep a str-fied instance since that is what
+    # we'll return.
+    resized_path_s = str(resized_path)
+
+    if resized_path.exists():
+        return resized_path_s
+
+    # if we dont, we need to generate it off the
+    # given image instance.
+
+    # NOTE: this is the same resize mode for icons.
+    resized = image.resize((width, height), resample=Image.LANCZOS)
+    resized.save(resized_path_s, format=ext)
+
+    return resized_path_s
+
 
 @bp.route('/attachments'
           '/<int:channel_id>/<int:message_id>/<filename>',
           methods=['GET'])
 async def _get_attachment(channel_id: int, message_id: int,
                           filename: str):
+
     attach_id = await app.db.fetchval("""
     SELECT id
     FROM attachments
@@ -38,5 +69,25 @@ async def _get_attachment(channel_id: int, message_id: int,
         return '', 404
 
     ext = filename.split('.')[-1]
+    filepath = f'./attachments/{attach_id}.{ext}'
 
-    return await send_file(f'./attachments/{attach_id}.{ext}')
+    image = Image.open(filepath)
+    im_width, im_height = image.size
+
+    try:
+        width = int(request.args.get('width', 0)) or im_width
+    except ValueError:
+        return '', 400
+
+    try:
+        height = int(request.args.get('height', 0)) or im_height
+    except ValueError:
+        return '', 400
+
+    # if width and height are the same (happens if they weren't provided)
+    if width == im_width and height == im_height:
+        return await send_file(filepath)
+
+    # resize image
+    new_filepath = await _resize(image, attach_id, ext, width, height)
+    return await send_file(new_filepath)