ugoira: store frame delays in MediaMetadata model.

Store Ugoira frame delays in the MediaMetadata model as a fake EXIF
field instead of in the PixivUgoiraFrameData model. This way we can get
rid of the PixivUgoiraFrameData model completely. This is a step towards
fixing #5264.

app/logical/media_file/ugoira.rb

@@ -22,6 +22,10 @@ class MediaFile::Ugoira < MediaFile
     preview_frame.close
   end
 
+  def metadata
+    super.merge("Ugoira:FrameDelays" => frame_delays)
+  end
+
   def dimensions
     preview_frame.dimensions
   end

app/models/post.rb

@@ -56,6 +56,7 @@ class Post < ApplicationRecord
   belongs_to :uploader, :class_name => "User", :counter_cache => "post_upload_count"
   belongs_to :parent, class_name: "Post", optional: true
   has_one :media_asset, -> { active }, foreign_key: :md5, primary_key: :md5
+  has_one :media_metadata, through: :media_asset
   has_one :artist_commentary, :dependent => :destroy
   has_one :pixiv_ugoira_frame_data, class_name: "PixivUgoiraFrameData", foreign_key: :md5, primary_key: :md5
   has_one :vote_by_current_user, -> { active.where(user_id: CurrentUser.id) }, class_name: "PostVote" # XXX using current user here is wrong

script/fixes/120_migrate_ugoira_frame_data.rb

@@ -0,0 +1,21 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+with_confirmation do
+  MediaMetadata.joins(:media_asset).where(media_asset: { file_ext: "zip" }).find_each do |meta|
+    frame_data = PixivUgoiraFrameData.find_by(md5: meta.media_asset.md5)
+
+    if frame_data.nil?
+      puts "Missing frame data: #{meta.media_asset.md5}"
+      next
+    elsif meta.metadata["Ugoira:FrameDelays"] == frame_data.frame_delays
+      next
+    end
+
+    json = meta.metadata.as_json.merge("Ugoira:FrameDelays" => frame_data.frame_delays)
+    meta.update!(metadata: json) if ENV.fetch("FIX", "false").truthy?
+
+    puts meta.as_json
+  end
+end

test/functional/post_replacements_controller_test.rb

@@ -129,6 +129,7 @@ class PostReplacementsControllerTest < ActionDispatch::IntegrationTest
 
           assert_equal("https://i.pximg.net/img-zip-ugoira/img/2017/04/04/08/57/38/62247364_ugoira1920x1080.zip", @post.source)
           assert_equal([{"delay" => 125, "file" => "000000.jpg"}, {"delay" => 125, "file" => "000001.jpg"}], @post.pixiv_ugoira_frame_data.data)
+          assert_equal([125, 125], @post.media_asset.metadata["Ugoira:FrameDelays"])
         end
       end
 

test/functional/uploads_controller_test.rb

@@ -287,6 +287,14 @@ class UploadsControllerTest < ActionDispatch::IntegrationTest
         end
       end
 
+      context "uploading a ugoira" do
+        should "work" do
+          upload = assert_successful_upload("https://www.pixiv.net/en/artworks/45982180", user: @user)
+
+          assert_equal([60] * 70, upload.media_assets.first.metadata["Ugoira:FrameDelays"])
+        end
+      end
+
       context "uploading a file from a source" do
         should_upload_successfully("https://www.artstation.com/artwork/04XA4")
         should_upload_successfully("https://dantewontdie.artstation.com/projects/YZK5q")