Fix edits with no actual changes being allowed (#17843)

* Fix edits with no actual changes being allowed locally

* Fix edits with no actual changes being allowed through ActivityPub

* Fix false positive changes caused by description processing in model

* Fix not recording poll expiration update

* Fix test

* Revert changes to ProcessStatusUpdateService

* Various fixes and improvements

* Fix code style issues

* Various changes and improvements

* Add guard clause

3 files changed, 37 insertions, 26 deletions

diff --git a/app/models/concerns/status_snapshot_concern.rb b/app/models/concerns/status_snapshot_concern.rb
new file mode 100644
index 000000000..9741b9aeb
--- /dev/null
+++ b/app/models/concerns/status_snapshot_concern.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module StatusSnapshotConcern
+  extend ActiveSupport::Concern
+
+  included do
+    has_many :edits, class_name: 'StatusEdit', inverse_of: :status, dependent: :destroy
+  end
+
+  def edited?
+    edited_at.present?
+  end
+
+  def build_snapshot(account_id: nil, at_time: nil, rate_limit: true)
+    # We don't use `edits#new` here to avoid it having saved when the
+    # status is saved, since we want to control that manually
+
+    StatusEdit.new(
+      status_id: id,
+      text: text,
+      spoiler_text: spoiler_text,
+      sensitive: sensitive,
+      ordered_media_attachment_ids: ordered_media_attachment_ids&.dup || media_attachments.pluck(:id),
+      media_descriptions: ordered_media_attachments.map(&:description),
+      poll_options: preloadable_poll&.options&.dup,
+      account_id: account_id || self.account_id,
+      created_at: at_time || edited_at,
+      rate_limit: rate_limit
+    )
+  end
+
+  def snapshot!(**options)
+    build_snapshot(**options).save!
+  end
+end
diff --git a/app/models/media_attachment.rb b/app/models/media_attachment.rb
index a3115637e..21c663e47 100644
--- a/app/models/media_attachment.rb
+++ b/app/models/media_attachment.rb
@@ -185,7 +185,7 @@ class MediaAttachment < ApplicationRecord
   remotable_attachment :thumbnail, IMAGE_LIMIT, suppress_errors: true, download_on_assign: false
 
   validates :account, presence: true
-  validates :description, length: { maximum: MAX_DESCRIPTION_LENGTH }, if: :local?
+  validates :description, length: { maximum: MAX_DESCRIPTION_LENGTH }
   validates :file, presence: true, if: :local?
   validates :thumbnail, absence: true, if: -> { local? && !audio_or_video? }
 
@@ -258,7 +258,6 @@ class MediaAttachment < ApplicationRecord
   after_commit :enqueue_processing, on: :create
   after_commit :reset_parent_cache, on: :update
 
-  before_create :prepare_description, unless: :local?
   before_create :set_unknown_type
   before_create :set_processing
 
@@ -306,10 +305,6 @@ class MediaAttachment < ApplicationRecord
     self.type = :unknown if file.blank? && !type_changed?
   end
 
-  def prepare_description
-    self.description = description.strip[0...MAX_DESCRIPTION_LENGTH] unless description.nil?
-  end
-
   def set_type_and_extension
     self.type = begin
       if VIDEO_MIME_TYPES.include?(file_content_type)
diff --git a/app/models/status.rb b/app/models/status.rb
index 5b984543e..bf5a49b7f 100644
--- a/app/models/status.rb
+++ b/app/models/status.rb
@@ -35,6 +35,7 @@ class Status < ApplicationRecord
   include Paginable
   include Cacheable
   include StatusThreadingConcern
+  include StatusSnapshotConcern
   include RateLimitable
 
   rate_limit by: :account, family: :statuses
@@ -59,8 +60,6 @@ class Status < ApplicationRecord
   belongs_to :thread, foreign_key: 'in_reply_to_id', class_name: 'Status', inverse_of: :replies, optional: true
   belongs_to :reblog, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblogs, optional: true
 
-  has_many :edits, class_name: 'StatusEdit', inverse_of: :status, dependent: :destroy
-
   has_many :favourites, inverse_of: :status, dependent: :destroy
   has_many :bookmarks, inverse_of: :status, dependent: :destroy
   has_many :reblogs, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblog, dependent: :destroy
@@ -212,24 +211,6 @@ class Status < ApplicationRecord
     public_visibility? || unlisted_visibility?
   end
 
-  def snapshot!(account_id: nil, at_time: nil, rate_limit: true)
-    edits.create!(
-      text: text,
-      spoiler_text: spoiler_text,
-      sensitive: sensitive,
-      ordered_media_attachment_ids: ordered_media_attachment_ids || media_attachments.pluck(:id),
-      media_descriptions: ordered_media_attachments.map(&:description),
-      poll_options: preloadable_poll&.options,
-      account_id: account_id || self.account_id,
-      created_at: at_time || edited_at,
-      rate_limit: rate_limit
-    )
-  end
-
-  def edited?
-    edited_at.present?
-  end
-
   alias sign? distributable?
 
   def with_media?