mod actions: record the subject of the mod action.

Add a polymorphic `subject` field that records the subject of the mod
action. The subject is the post, user, comment, artist, etc the mod
action is for.

* The subject for the user ban and unban actions is the user, not the ban itself.
* The subject for the user feedback update and deletion actions is the user,
  not the feedback itself.
* The subject for the post undeletion action is the post, not the approval itself.
* The subject for the move favorites action is the source post where the
  favorites were moved from, not the destination post where the favorites
  were moved to.
* The subject for the post permanent delete action is nil, because the
  post itself is hard deleted.
* When a post is permanently deleted, all mod actions related to the
  post are deleted as well.

app/models/artist.rb

@@ -24,6 +24,7 @@ class Artist < ApplicationRecord
   has_many :members, :class_name => "Artist", :foreign_key => "group_name", :primary_key => "name"
   has_many :urls, dependent: :destroy, class_name: "ArtistURL", autosave: true
   has_many :versions, -> {order("artist_versions.id ASC")}, :class_name => "ArtistVersion"
+  has_many :mod_actions, as: :subject, dependent: :destroy
   has_one :wiki_page, -> { active }, foreign_key: "title", primary_key: "name"
   has_one :tag_alias, -> { active }, foreign_key: "antecedent_name", primary_key: "name"
   belongs_to :tag, foreign_key: "name", primary_key: "name", default: -> { Tag.new(name: name, category: Tag.categories.artist) }
@@ -192,25 +193,25 @@ class Artist < ApplicationRecord
   end
 
   module BanMethods
-    def unban!
+    def unban!(current_user = CurrentUser.user)
       Post.transaction do
         ti = TagImplication.find_by(antecedent_name: name, consequent_name: "banned_artist")
         ti&.destroy
 
         Post.raw_tag_match(name).find_each do |post|
-          post.unban!
+          post.unban!(current_user)
           fixed_tags = post.tag_string.sub(/(?:\A| )banned_artist(?:\Z| )/, " ").strip
-          post.update(tag_string: fixed_tags)
+          post.update(tag_string: fixed_tags) # XXX should use current_user
         end
 
-        update!(is_banned: false)
-        ModAction.log("unbanned artist ##{id}", :artist_unban)
+        update!(is_banned: false) # XXX should use current_user
+        ModAction.log("unbanned artist ##{id}", :artist_unban, subject: self, user: current_user)
       end
     end
 
     def ban!(banner: CurrentUser.user)
       Post.transaction do
-        Post.raw_tag_match(name).each(&:ban!)
+        Post.raw_tag_match(name).each { |post| post.ban!(banner) }
 
         # potential race condition but unlikely
         unless TagImplication.where(:antecedent_name => name, :consequent_name => "banned_artist").exists?
@@ -219,7 +220,7 @@ class Artist < ApplicationRecord
         end
 
         update!(is_banned: true)
-        ModAction.log("banned artist ##{id}", :artist_ban)
+        ModAction.log("banned artist ##{id}", :artist_ban, subject: self, user: banner)
       end
     end
   end

app/models/ban.rb

@@ -81,11 +81,11 @@ class Ban < ApplicationRecord
   end
 
   def create_ban_mod_action
-    ModAction.log(%{banned <@#{user_name}> #{humanized_duration}: #{reason}}, :user_ban, banner)
+    ModAction.log(%{banned <@#{user_name}> #{humanized_duration}: #{reason}}, :user_ban, subject: user, user: banner)
   end
 
   def create_unban_mod_action
-    ModAction.log(%{unbanned <@#{user_name}>}, :user_unban)
+    ModAction.log(%{unbanned <@#{user_name}>}, :user_unban, subject: user, user: CurrentUser.user)
   end
 
   def self.available_includes

app/models/comment.rb

@@ -10,6 +10,7 @@ class Comment < ApplicationRecord
   has_many :moderation_reports, as: :model, dependent: :destroy
   has_many :pending_moderation_reports, -> { pending }, as: :model, class_name: "ModerationReport"
   has_many :votes, class_name: "CommentVote", dependent: :destroy
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   validates :body, presence: true, length: { maximum: 15_000 }, if: :body_changed?
 
@@ -17,11 +18,11 @@ class Comment < ApplicationRecord
   before_save :handle_reports_on_deletion
   after_create :update_last_commented_at_on_create
   after_update(:if => ->(rec) {(!rec.is_deleted? || !rec.saved_change_to_is_deleted?) && CurrentUser.id != rec.creator_id}) do |comment|
-    ModAction.log("updated #{comment.dtext_shortlink}", :comment_update, comment.updater)
+    ModAction.log("updated #{comment.dtext_shortlink}", :comment_update, subject: self, user: comment.updater)
   end
   after_save :update_last_commented_at_on_destroy, :if => ->(rec) {rec.is_deleted? && rec.saved_change_to_is_deleted?}
   after_save(:if => ->(rec) {rec.is_deleted? && rec.saved_change_to_is_deleted? && CurrentUser.id != rec.creator_id}) do |comment|
-    ModAction.log("deleted #{comment.dtext_shortlink}", :comment_delete, comment.updater)
+    ModAction.log("deleted #{comment.dtext_shortlink}", :comment_delete, subject: self, user: comment.updater)
   end
 
   deletable

app/models/comment_vote.rb

@@ -5,6 +5,7 @@ class CommentVote < ApplicationRecord
 
   belongs_to :comment
   belongs_to :user
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   validate :validate_vote_is_unique, if: :is_deleted_changed?
   validates :score, inclusion: { in: [-1, 1], message: "must be 1 or -1" }
@@ -56,13 +57,13 @@ class CommentVote < ApplicationRecord
         comment.update_columns(score: comment.score - score)
 
         if updater != user
-          ModAction.log("deleted comment vote ##{id} on comment ##{comment_id}", :comment_vote_delete, updater)
+          ModAction.log("deleted comment vote ##{id} on comment ##{comment_id}", :comment_vote_delete, subject: self, user: updater)
         end
       else
         comment.update_columns(score: comment.score + score)
 
         if updater != user
-          ModAction.log("undeleted comment vote ##{id} on comment ##{comment_id}", :comment_vote_undelete, updater)
+          ModAction.log("undeleted comment vote ##{id} on comment ##{comment_id}", :comment_vote_undelete, subject: self, user: updater)
         end
       end
     end

app/models/forum_post.rb

@@ -11,6 +11,7 @@ class ForumPost < ApplicationRecord
   has_many :moderation_reports, as: :model
   has_many :pending_moderation_reports, -> { pending }, as: :model, class_name: "ModerationReport"
   has_many :votes, class_name: "ForumPostVote"
+  has_many :mod_actions, as: :subject, dependent: :destroy
   has_one :tag_alias
   has_one :tag_implication
   has_one :bulk_update_request
@@ -25,10 +26,10 @@ class ForumPost < ApplicationRecord
   after_update :update_topic_updated_at_on_update_for_original_posts
   after_destroy :update_topic_updated_at_on_destroy
   after_update(:if => ->(rec) {rec.updater_id != rec.creator_id}) do |forum_post|
-    ModAction.log("updated #{forum_post.dtext_shortlink}", :forum_post_update, forum_post.updater)
+    ModAction.log("updated #{forum_post.dtext_shortlink}", :forum_post_update, subject: self, user: forum_post.updater)
   end
   after_destroy(:if => ->(rec) {rec.updater_id != rec.creator_id}) do |forum_post|
-    ModAction.log("deleted #{forum_post.dtext_shortlink}", :forum_post_delete, forum_post.updater)
+    ModAction.log("deleted #{forum_post.dtext_shortlink}", :forum_post_delete, subject: self, user: forum_post.updater)
   end
   after_create_commit :async_send_discord_notification
 

app/models/forum_topic.rb

@@ -22,6 +22,7 @@ class ForumTopic < ApplicationRecord
   has_many :bulk_update_requests
   has_many :tag_aliases
   has_many :tag_implications
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   validates :title, presence: true, length: { maximum: 200 }, if: :title_changed?
   validates :category_id, inclusion: { in: CATEGORIES.keys }
@@ -32,7 +33,7 @@ class ForumTopic < ApplicationRecord
   after_update :update_posts_on_deletion_or_undeletion
   after_update :update_original_post
   after_save(:if => ->(rec) {rec.is_locked? && rec.saved_change_to_is_locked?}) do |rec|
-    ModAction.log("locked forum topic ##{id} (title: #{title})", :forum_topic_lock)
+    ModAction.log("locked forum topic ##{id} (title: #{title})", :forum_topic_lock, subject: self, user: CurrentUser.user)
   end
 
   deletable
@@ -164,11 +165,11 @@ class ForumTopic < ApplicationRecord
   end
 
   def create_mod_action_for_delete
-    ModAction.log("deleted forum topic ##{id} (title: #{title})", :forum_topic_delete)
+    ModAction.log("deleted forum topic ##{id} (title: #{title})", :forum_topic_delete, subject: self, user: CurrentUser.user)
   end
 
   def create_mod_action_for_undelete
-    ModAction.log("undeleted forum topic ##{id} (title: #{title})", :forum_topic_undelete)
+    ModAction.log("undeleted forum topic ##{id} (title: #{title})", :forum_topic_undelete, subject: self, user: CurrentUser.user)
   end
 
   def page_for(post_id)

app/models/ip_ban.rb

@@ -4,11 +4,12 @@ class IpBan < ApplicationRecord
   attribute :ip_addr, :ip_address
 
   belongs_to :creator, class_name: "User"
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   validate :validate_ip_addr
   validates :reason, presence: true
 
-  before_save :create_mod_action
+  after_save :create_mod_action
 
   deletable
   enum category: {
@@ -52,12 +53,12 @@ class IpBan < ApplicationRecord
   end
 
   def create_mod_action
-    if new_record?
-      ModAction.log("created ip ban for #{ip_addr}", :ip_ban_create, creator)
-    elsif is_deleted? == true && is_deleted_was == false
-      ModAction.log("deleted ip ban for #{ip_addr}", :ip_ban_delete)
-    elsif is_deleted? == false && is_deleted_was == true
-      ModAction.log("undeleted ip ban for #{ip_addr}", :ip_ban_undelete)
+    if previously_new_record?
+      ModAction.log("created ip ban for #{ip_addr}", :ip_ban_create, subject: self, user: creator)
+    elsif is_deleted? == true && is_deleted_before_last_save == false
+      ModAction.log("deleted ip ban for #{ip_addr}", :ip_ban_delete, subject: self, user: CurrentUser.user)
+    elsif is_deleted? == false && is_deleted_before_last_save == true
+      ModAction.log("undeleted ip ban for #{ip_addr}", :ip_ban_undelete, subject: self, user: CurrentUser.user)
     end
   end
 

app/models/mod_action.rb

@@ -2,6 +2,7 @@
 
 class ModAction < ApplicationRecord
   belongs_to :creator, :class_name => "User"
+  belongs_to :subject, polymorphic: true, optional: true
 
   # ####DIVISIONS#####
   # Groups:     0-999
@@ -70,6 +71,10 @@ class ModAction < ApplicationRecord
     other: 2000,
   }
 
+  def self.model_types
+    %w[Artist Comment CommentVote ForumPost ForumTopic IpBan ModerationReport Pool Post PostVote Tag TagAlias TagImplication User UserFeedback]
+  end
+
   def self.visible(user)
     if user.is_moderator?
       all
@@ -79,7 +84,7 @@ class ModAction < ApplicationRecord
   end
 
   def self.search(params, current_user)
-    q = search_attributes(params, [:id, :created_at, :updated_at, :category, :description, :creator], current_user: current_user)
+    q = search_attributes(params, [:id, :created_at, :updated_at, :category, :description, :creator, :subject], current_user: current_user)
 
     case params[:order]
     when "created_at_asc"
@@ -95,8 +100,8 @@ class ModAction < ApplicationRecord
     self.class.categories[category]
   end
 
-  def self.log(desc, cat = :other, user = CurrentUser.user)
-    create(creator: user, description: desc, category: categories[cat])
+  def self.log(description, category, subject:, user:)
+    create!(description: description, category: category, subject: subject, creator: user)
   end
 
   def self.available_includes

app/models/moderation_report.rb

@@ -7,6 +7,7 @@ class ModerationReport < ApplicationRecord
 
   belongs_to :model, polymorphic: true
   belongs_to :creator, class_name: "User"
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   before_validation(on: :create) { model.lock! }
   validates :reason, presence: true
@@ -61,9 +62,9 @@ class ModerationReport < ApplicationRecord
     return unless saved_change_to_status? && status != :pending
 
     if handled?
-      ModAction.log("handled modreport ##{id}", :moderation_report_handled, updater)
+      ModAction.log("handled modreport ##{id}", :moderation_report_handled, subject: self, user: updater)
     elsif rejected?
-      ModAction.log("rejected modreport ##{id}", :moderation_report_rejected, updater)
+      ModAction.log("rejected modreport ##{id}", :moderation_report_rejected, subject: self, user: updater)
     end
   end
 

app/models/pool.rb

@@ -14,6 +14,8 @@ class Pool < ApplicationRecord
   before_validation :normalize_name
   after_save :create_version
 
+  has_many :mod_actions, as: :subject, dependent: :destroy
+
   deletable
   has_dtext_links :description
 
@@ -157,11 +159,11 @@ class Pool < ApplicationRecord
   end
 
   def create_mod_action_for_delete
-    ModAction.log("deleted pool ##{id} (name: #{name})", :pool_delete)
+    ModAction.log("deleted pool ##{id} (name: #{name})", :pool_delete, subject: self, user: CurrentUser.user)
   end
 
   def create_mod_action_for_undelete
-    ModAction.log("undeleted pool ##{id} (name: #{name})", :pool_undelete)
+    ModAction.log("undeleted pool ##{id} (name: #{name})", :pool_undelete, subject: self, user: CurrentUser.user)
   end
 
   def add!(post)

app/models/post.rb

@@ -71,6 +71,7 @@ class Post < ApplicationRecord
   has_many :replacements, class_name: "PostReplacement", :dependent => :destroy
   has_many :ai_tags, through: :media_asset
   has_many :events, class_name: "PostEvent"
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   attr_accessor :old_tag_string, :old_parent_id, :old_source, :old_rating, :has_constraints, :disable_versioning, :post_edit
 
@@ -516,11 +517,11 @@ class Post < ApplicationRecord
 
         in "status", "banned"
           raise User::PrivilegeError unless CurrentUser.is_approver?
-          ban!
+          ban!(CurrentUser.user)
 
         in "-status", "banned"
           raise User::PrivilegeError unless CurrentUser.is_approver?
-          unban!
+          unban!(CurrentUser.user)
 
         in "disapproved", reason
           raise User::PrivilegeError unless CurrentUser.is_approver?
@@ -732,7 +733,7 @@ class Post < ApplicationRecord
       nil
     end
 
-    def give_favorites_to_parent
+    def give_favorites_to_parent(current_user = CurrentUser.user)
       return if parent.nil?
 
       transaction do
@@ -742,7 +743,7 @@ class Post < ApplicationRecord
         end
       end
 
-      ModAction.log("moved favorites from post ##{id} to post ##{parent.id}", :post_move_favorites)
+      ModAction.log("moved favorites from post ##{id} to post ##{parent.id}", :post_move_favorites, subject: self, user: current_user)
     end
 
     def has_visible_children?
@@ -758,10 +759,10 @@ class Post < ApplicationRecord
   end
 
   concerning :DeletionMethods do
-    def expunge!
+    def expunge!(current_user = CurrentUser.user)
       transaction do
         Post.without_timeout do
-          ModAction.log("permanently deleted post ##{id} (md5=#{md5})", :post_permanent_delete)
+          ModAction.log("permanently deleted post ##{id} (md5=#{md5})", :post_permanent_delete, subject: nil, user: current_user)
 
           update_children_on_destroy
           decrement_tag_post_counts
@@ -776,16 +777,16 @@ class Post < ApplicationRecord
       remove_iqdb # this is non-transactional
     end
 
-    def ban!
+    def ban!(current_user)
       return if is_banned?
       update_column(:is_banned, true)
-      ModAction.log("banned post ##{id}", :post_ban)
+      ModAction.log("banned post ##{id}", :post_ban, subject: self, user: current_user)
     end
 
-    def unban!
+    def unban!(current_user)
       return unless is_banned?
       update_column(:is_banned, false)
-      ModAction.log("unbanned post ##{id}", :post_unban)
+      ModAction.log("unbanned post ##{id}", :post_unban, subject: self, user: current_user)
     end
 
     def delete!(reason, move_favorites: false, user: CurrentUser.user)
@@ -804,7 +805,7 @@ class Post < ApplicationRecord
         uploader.upload_limit.update_limit!(is_pending?, false)
 
         unless automated
-          ModAction.log("deleted post ##{id}, reason: #{reason}", :post_delete)
+          ModAction.log("deleted post ##{id}, reason: #{reason}", :post_delete, subject: self, user: user)
         end
       end
     end
@@ -1449,7 +1450,7 @@ class Post < ApplicationRecord
       if category == "iqdb"
         update_iqdb
 
-        ModAction.log("regenerated IQDB for post ##{id}", :post_regenerate_iqdb, user)
+        ModAction.log("regenerated IQDB for post ##{id}", :post_regenerate_iqdb, subject: self, user: user)
       else
         media_file = media_asset.variant(:original).open_file
         media_asset.distribute_files!(media_file)
@@ -1471,7 +1472,7 @@ class Post < ApplicationRecord
         purge_cached_urls!
         update_iqdb
 
-        ModAction.log("regenerated image samples for post ##{id}", :post_regenerate, user)
+        ModAction.log("regenerated image samples for post ##{id}", :post_regenerate, subject: self, user: user)
       end
     end
 

app/models/post_approval.rb

@@ -31,7 +31,7 @@ class PostApproval < ApplicationRecord
     post.appeals.pending.update!(status: :succeeded)
 
     post.update(approver: user, is_flagged: false, is_pending: false, is_deleted: false)
-    ModAction.log("undeleted post ##{post_id}", :post_undelete, user) if is_undeletion
+    ModAction.log("undeleted post ##{post_id}", :post_undelete, subject: post, user: user) if is_undeletion
 
     post.uploader.upload_limit.update_limit!(is_pending, true)
   end

app/models/post_vote.rb

@@ -5,6 +5,7 @@ class PostVote < ApplicationRecord
 
   belongs_to :post
   belongs_to :user
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   validates :score, inclusion: { in: [1, -1], message: "must be 1 or -1" }
 
@@ -81,9 +82,9 @@ class PostVote < ApplicationRecord
     return if new_record? || updater.nil? || updater == user
 
     if is_deleted_changed?(from: false, to: true)
-      ModAction.log("deleted post vote ##{id} on post ##{post_id}", :post_vote_delete, updater)
+      ModAction.log("deleted post vote ##{id} on post ##{post_id}", :post_vote_delete, subject: self, user: updater)
     elsif is_deleted_changed?(from: true, to: false)
-      ModAction.log("undeleted post vote ##{id} on post ##{post_id}", :post_vote_undelete, updater)
+      ModAction.log("undeleted post vote ##{id} on post ##{post_id}", :post_vote_undelete, subject: self, user: updater)
     end
   end
 

app/models/tag_relationship.rb

@@ -13,6 +13,7 @@ class TagRelationship < ApplicationRecord
   belongs_to :consequent_tag, class_name: "Tag", foreign_key: "consequent_name", primary_key: "name", default: -> { Tag.find_or_create_by_name(consequent_name) }
   belongs_to :antecedent_wiki, class_name: "WikiPage", foreign_key: "antecedent_name", primary_key: "title", optional: true
   belongs_to :consequent_wiki, class_name: "WikiPage", foreign_key: "consequent_name", primary_key: "title", optional: true
+  has_many :mod_actions, as: :subject, dependent: :destroy
 
   scope :active, -> {where(status: "active")}
   scope :deleted, -> {where(status: "deleted")}
@@ -61,7 +62,7 @@ class TagRelationship < ApplicationRecord
 
     if rejector != User.system
       category = relationship == "tag alias" ? :tag_alias_delete : :tag_implication_delete
-      ModAction.log("deleted #{relationship} #{antecedent_name} -> #{consequent_name}", category, rejector)
+      ModAction.log("deleted #{relationship} #{antecedent_name} -> #{consequent_name}", category, subject: self, user: rejector)
     end
   end
 

app/models/user.rb

@@ -139,6 +139,7 @@ class User < ApplicationRecord
   has_many :tag_implications, foreign_key: :creator_id
   has_many :uploads, foreign_key: :uploader_id, dependent: :destroy
   has_many :upload_media_assets, through: :uploads, dependent: :destroy
+  has_many :mod_actions, as: :subject, dependent: :destroy
   belongs_to :inviter, class_name: "User", optional: true
 
   accepts_nested_attributes_for :email_address, reject_if: :all_blank, allow_destroy: true

app/models/user_feedback.rb

@@ -11,10 +11,10 @@ class UserFeedback < ApplicationRecord
   validates :category, presence: true, inclusion: { in: %w[positive negative neutral] }
   after_create :create_dmail, unless: :disable_dmail_notification
   after_update(:if => ->(rec) { CurrentUser.id != rec.creator_id}) do |rec|
-    ModAction.log(%{updated user feedback for "#{rec.user.name}":#{Routes.user_path(rec.user)}}, :user_feedback_update)
+    ModAction.log(%{updated user feedback for "#{rec.user.name}":#{Routes.user_path(rec.user)}}, :user_feedback_update, subject: user, user: CurrentUser.user)
   end
   after_destroy(:if => ->(rec) { CurrentUser.id != rec.creator_id}) do |rec|
-    ModAction.log(%{deleted user feedback for "#{rec.user.name}":#{Routes.user_path(rec.user)}}, :user_feedback_delete)
+    ModAction.log(%{deleted user feedback for "#{rec.user.name}":#{Routes.user_path(rec.user)}}, :user_feedback_delete, subject: user, user: CurrentUser.user)
   end
 
   deletable