Fix #3272: Unicode tags are still being allowed.

* Don't allow adding tags with invalid names when they already exist in
  the tags table.
* If an invalid tag is added, show an warning and ignore the tag instead
  of failing with a hard error.
* Move the _(cosplay) tag validation into the tag name validator.

app/logical/tag_name_validator.rb

@@ -17,14 +17,21 @@ class TagNameValidator < ActiveModel::EachValidator
       record.errors[attribute] << "'#{value}' cannot end with an underscore"
     when /__/
       record.errors[attribute] << "'#{value}' cannot contain consecutive underscores"
-    when /[^[[:graph:]]]/
+    when /[^[:graph:]]/
       record.errors[attribute] << "'#{value}' cannot contain non-printable characters"
-    when /[^[[:ascii:]]]/
+    when /[^[:ascii:]]/
       record.errors[attribute] << "'#{value}' must consist of only ASCII characters"
     when /\A(#{Tag::METATAGS.join("|")}):(.+)\z/i
       record.errors[attribute] << "'#{value}' cannot begin with '#{$1}:'"
     when /\A(#{Tag.categories.regexp}):(.+)\z/i
       record.errors[attribute] << "'#{value}' cannot begin with '#{$1}:'"
+    when /\A(.+)_\(cosplay\)\z/i
+      tag_name = TagAlias.to_aliased([$1]).first
+      tag = Tag.find_by_name(tag_name)
+
+      if tag.present? && tag.category != Tag.categories.character
+        record.errors[attribute] << "#{tag_name} must be a character tag"
+      end
     end
   end
 end

app/models/post.rb

@@ -21,7 +21,6 @@ class Post < ApplicationRecord
   before_validation :remove_parent_loops
   validates_uniqueness_of :md5, :on => :create, message: ->(obj, data) { "duplicate: #{Post.find_by_md5(obj.md5).id}"}
   validates_inclusion_of :rating, in: %w(s q e), message: "rating must be s, q, or e"
-  validate :tag_names_are_valid
   validate :added_tags_are_valid
   validate :removed_tags_are_valid
   validate :has_artist_tag
@@ -662,12 +661,16 @@ class Post < ApplicationRecord
       set_tag_string(normalized_tags.join(" "))
     end
 
-    def remove_invalid_tags(tags)
-      invalid_tags = Tag.invalid_cosplay_tags(tags)
-      if invalid_tags.present?
-        self.warnings[:base] << "The root tag must be a character tag: #{invalid_tags.map {|tag| "[b]#{tag}[/b]" }.join(", ")}"
+    def remove_invalid_tags(tag_names)
+      invalid_tags = tag_names.map { |name| Tag.new(name: name) }.select { |tag| tag.invalid?(:name) }
+
+      invalid_tags.each do |tag|
+        tag.errors.messages.each do |attribute, messages|
+          warnings[:base] << "Couldn't add tag: #{messages.join(';')}"
+        end
       end
-      tags - invalid_tags
+
+      tag_names - invalid_tags.map(&:name)
     end
 
     def remove_negated_tags(tags)
@@ -1755,22 +1758,6 @@ class Post < ApplicationRecord
       end
     end
 
-    def tag_names_are_valid
-      # only validate new tags; allow invalid names for tags that already exist.
-      added_tags = tag_array - tag_array_was
-      new_tags = added_tags - Tag.where(name: added_tags).pluck(:name)
-
-      new_tags.each do |name|
-        tag = Tag.new
-        tag.name = name
-        tag.valid?
-
-        tag.errors.messages.each do |attribute, messages|
-          errors[:tag_string] << "tag #{attribute} #{messages.join(';')}"
-        end
-      end
-    end
-
     def added_tags_are_valid
       new_tags = added_tags.select { |t| t.post_count <= 0 }
       new_general_tags = new_tags.select { |t| t.category == Tag.categories.general }

app/models/tag.rb

@@ -52,7 +52,8 @@ class Tag < ApplicationRecord
   has_many :antecedent_implications, -> {active}, :class_name => "TagImplication", :foreign_key => "antecedent_name", :primary_key => "name"
   has_many :consequent_implications, -> {active}, :class_name => "TagImplication", :foreign_key => "consequent_name", :primary_key => "name"
 
-  validates :name, uniqueness: true, tag_name: true, on: :create
+  validates :name, tag_name: true, uniqueness: true, on: :create
+  validates :name, tag_name: true, on: :name
   validates_inclusion_of :category, in: TagCategory.category_ids
 
   before_save :update_category_cache, if: :category_changed?
@@ -1019,14 +1020,6 @@ class Tag < ApplicationRecord
     cosplay_tags.grep(/\A(.+)_\(cosplay\)\Z/) { "#{TagAlias.to_aliased([$1]).first}_(cosplay)" } + other_tags
   end
 
-  def self.invalid_cosplay_tags(tags)
-    tags.grep(/\A(.+)_\(cosplay\)\Z/) {|match| [match,TagAlias.to_aliased([$1]).first] }.
-      select do |name|
-        tag = Tag.find_by_name(name[1])
-        !tag.nil? && tag.category != Tag.categories.character
-      end.map {|tag| tag[0]}
-  end
-
   def editable_by?(user)
     return true if user.is_admin?
     return true if !is_locked? && user.is_builder? && post_count < 1_000