thumbnail: Add flag for when thumbnail files are missing.

(cherry picked from commit de67d37884)

zerver/management/commands/thumbnail.py

@@ -2,12 +2,16 @@ from datetime import timedelta
 from typing import Any
 
 from django.core.management.base import CommandParser
+from django.db.models import Exists, OuterRef
 from django.utils.timezone import now as timezone_now
 from typing_extensions import override
 
 from zerver.actions.message_edit import re_thumbnail
 from zerver.lib.management import ZulipBaseCommand
-from zerver.models import ArchivedMessage, Message
+from zerver.lib.queue import queue_event_on_commit
+from zerver.lib.thumbnail import StoredThumbnailFormat, get_image_thumbnail_path
+from zerver.lib.upload import all_message_attachments
+from zerver.models import ArchivedMessage, Attachment, ImageAttachment, Message
 
 
 class Command(ZulipBaseCommand):
@@ -23,7 +27,14 @@ class Command(ZulipBaseCommand):
             help="Attempt to re-render messages with stuck spinners",
         )
         mode.add_argument(
-            "--old-images", action="store_true", help="Generate thumbnails of old images"
+            "--old-images",
+            action="store_true",
+            help="Generate thumbnails of old images",
+        )
+        mode.add_argument(
+            "--missing-files",
+            action="store_true",
+            help="Regenerate thumbnails when their files are missing",
         )
         parser.add_argument(
             "--cutoff",
@@ -37,6 +48,35 @@ class Command(ZulipBaseCommand):
         realm = self.get_realm(options)
         assert realm is not None
 
+        if options.get("missing_files"):
+            realm_imageattachments = (
+                ImageAttachment.objects.alias(
+                    in_realm=Exists(
+                        Attachment.objects.filter(path_id=OuterRef("path_id"), realm_id=realm.id)
+                    )
+                )
+                .filter(in_realm=True)
+                .exclude(thumbnail_metadata=[])
+            )
+            for image_attachment in realm_imageattachments:
+                found = []
+                changed = False
+                thumb_dir = f"thumbnail/{image_attachment.path_id}"
+                found_thumbs = [
+                    e[0] for e in all_message_attachments(include_thumbnails=True, prefix=thumb_dir)
+                ]
+                for existing_thumbnail in image_attachment.thumbnail_metadata:
+                    thumb = StoredThumbnailFormat(**existing_thumbnail)
+                    if get_image_thumbnail_path(image_attachment, thumb) in found_thumbs:
+                        found.append(existing_thumbnail)
+                    else:
+                        changed = True
+                if changed:
+                    image_attachment.thumbnail_metadata = found
+                    image_attachment.save(update_fields=["thumbnail_metadata"])
+                    queue_event_on_commit("thumbnail", {"id": image_attachment.id})
+            return
+
         for message_class in (Message, ArchivedMessage):
             messages = message_class.objects.filter(
                 realm_id=realm.id,
@@ -48,7 +88,7 @@ class Command(ZulipBaseCommand):
                     rendered_content__contains='class="image-loading-placeholder"',
                     date_sent__lt=timezone_now() - timedelta(seconds=60),
                 )
-            else:
+            elif options.get("old_images"):
                 messages = messages.filter(
                     rendered_content__contains='<img src="/user_uploads/',
                 ).exclude(