FIX: Do not overwrite existing thumbnails (#21199)

* FIX: Do not overwrite existing thumbnails

When auto generating video thumbnails they should not overwrite any
existing topic thumbnails.

This also addresses an issue with capitalized file extensions like .MOV
that were being excluded.

* Update app/models/post.rb

Remove comment

Co-authored-by: Penar Musaraj <pmusaraj@gmail.com>

---------

Co-authored-by: Penar Musaraj <pmusaraj@gmail.com>

app/models/post.rb

@@ -1013,24 +1013,21 @@ class Post < ActiveRecord::Base
       upload ||= Upload.get_from_url(src)
 
       # Link any video thumbnails
-      if upload.present? && (FileHelper.supported_video.include? upload.extension)
+      if upload.present? && (FileHelper.supported_video.include? upload.extension&.downcase)
         # Video thumbnails have the filename of the video file sha1 with a .png or .jpg extension.
         # This is because at time of upload in the composer we don't know the topic/post id yet
         # and there is no thumbnail info added to the markdown to tie the thumbnail to the topic/post after
         # creation.
         thumbnail =
           Upload.where("original_filename like ?", "#{upload.sha1}.%").first if upload.sha1.present?
-        if thumbnail.present?
-          upload_ids << thumbnail.id if thumbnail.present?
-
-          if self.is_first_post? #topic
-            self.topic.update_column(:image_upload_id, thumbnail.id)
-            extra_sizes =
-              ThemeModifierHelper.new(
-                theme_ids: Theme.user_selectable.pluck(:id),
-              ).topic_thumbnail_sizes
-            self.topic.generate_thumbnails!(extra_sizes: extra_sizes)
-          end
+        if thumbnail.present? && self.is_first_post? && !self.topic.image_upload_id
+          upload_ids << thumbnail.id
+          self.topic.update_column(:image_upload_id, thumbnail.id)
+          extra_sizes =
+            ThemeModifierHelper.new(
+              theme_ids: Theme.user_selectable.pluck(:id),
+            ).topic_thumbnail_sizes
+          self.topic.generate_thumbnails!(extra_sizes: extra_sizes)
         end
       end
       upload_ids << upload.id if upload.present?

spec/models/post_spec.rb

@@ -1566,6 +1566,17 @@ RSpec.describe Post do
       post.topic.reload
       expect(post.topic.topic_thumbnails.length).to eq(0)
     end
+
+    it "does not overwrite existing thumbnails" do
+      image_upload.original_filename = "#{video_upload.sha1}.png"
+      image_upload.save!
+      post.topic.image_upload_id = image_upload_2.id
+      post.topic.save!
+      post.link_post_uploads
+
+      post.topic.reload
+      expect(post.topic.image_upload_id).to eq(image_upload_2.id)
+    end
   end
 
   describe "uploads" do