Fix #4491: Have tag rename option for bulk update requests.

* Add a `rename A -> B` command for bulk update requests.
* Change mass updates to only retag the posts, not to move saved
  searches or blacklists.

A tag rename does the same thing an alias does, except it doesn't
create a permanent alias. More precisely, a tag rename:

* Moves the wiki.
* Moves the artist entry.
* Moves saved searches.
* Moves blacklists.
* Merges the wikis, if both tags have wiki pages.
* Merges the artist entries, if both tags have artist pages.
* Fixes links in wiki pages to point to the new tag.
* Retags the posts.

app/jobs/tag_batch_change_job.rb

@@ -1,19 +1,12 @@
 class TagBatchChangeJob < ApplicationJob
-  class Error < StandardError; end
-
   queue_as :bulk_update
 
-  def perform(antecedent, consequent, updater, updater_ip_addr)
-    raise Error.new("antecedent is missing") if antecedent.blank?
-
+  def perform(antecedent, consequent)
     normalized_antecedent = PostQueryBuilder.new(antecedent).split_query
     normalized_consequent = PostQueryBuilder.new(consequent).parse_tag_edit
 
-    CurrentUser.scoped(updater, updater_ip_addr) do
+    CurrentUser.scoped(User.system) do
       migrate_posts(normalized_antecedent, normalized_consequent)
-      migrate_saved_searches(normalized_antecedent, normalized_consequent)
-      migrate_blacklists(normalized_antecedent, normalized_consequent)
-
       ModAction.log("processed mass update: #{antecedent} -> #{consequent}", :mass_update)
     end
   end
@@ -26,47 +19,4 @@ class TagBatchChangeJob < ApplicationJob
       end
     end
   end
-
-  def migrate_saved_searches(normalized_antecedent, normalized_consequent)
-    tags = PostQueryBuilder.new(normalized_antecedent.join(" ")).split_query
-
-    # https://www.postgresql.org/docs/current/static/functions-array.html
-    saved_searches = SavedSearch.where("string_to_array(query, ' ') @> ARRAY[?]", tags)
-    saved_searches.find_each do |ss|
-      ss.query = (ss.query.split - tags + normalized_consequent).uniq.join(" ")
-      ss.save
-    end
-  end
-
-  # this can't handle negated tags or other special cases
-  def migrate_blacklists(normalized_antecedent, normalized_consequent)
-    query = normalized_antecedent
-    adds = normalized_consequent
-    arel = query.inject(User.none) do |scope, x|
-      scope.or(User.where_like(:blacklisted_tags, "*#{x}*"))
-    end
-
-    arel.find_each do |user|
-      changed = false
-
-      begin
-        repl = user.blacklisted_tags.split(/\r\n|\r|\n/).map do |line|
-          list = PostQueryBuilder.new(line).split_query
-
-          if (list & query).size != query.size
-            next line
-          end
-
-          changed = true
-          (list - query + adds).join(" ")
-        end
-
-        if changed
-          user.update(blacklisted_tags: repl.join("\n"))
-        end
-      rescue Exception => e
-        DanbooruLogger.log(e)
-      end
-    end
-  end
 end

app/jobs/tag_rename_job.rb

@@ -0,0 +1,7 @@
+class TagRenameJob < ApplicationJob
+  queue_as :bulk_update
+
+  def perform(old_tag_name, new_tag_name)
+    TagMover.new(old_tag_name, new_tag_name, user: User.system).move!
+  end
+end