Fix #3208: Fix translated tag suggestions for Pixiv.

* Only suggest the Danbooru tag with the same name if there is no
  matching wiki other name. Example: if we have the Pixiv tag `Fate` and
  the Danbooru tag `fate_(series)` with other name `fate`, suggest that,
  not the Danbooru tag `fate`.

* Don't suggest tags that are empty or whose wiki is deleted.

* Only split tags on "/" if there are no other matches, and only for Pixiv.

* For Pixiv, only include traditional media tags in tag list, not digital media (Photoshop, SAI).

* Add some tests.

app/logical/sources/site.rb

@@ -8,7 +8,7 @@ module Sources
       :file_url, :ugoira_frame_data, :ugoira_content_type, :image_urls,
       :artist_commentary_title, :artist_commentary_desc,
       :dtext_artist_commentary_title, :dtext_artist_commentary_desc,
-      :rewrite_thumbnails, :illust_id_from_url, :to => :strategy
+      :rewrite_thumbnails, :illust_id_from_url, :translate_tag, :translated_tags, :to => :strategy
 
     def self.strategies
       [Strategies::PixivWhitecube, Strategies::Pixiv, Strategies::NicoSeiga, Strategies::DeviantArt, Strategies::ArtStation, Strategies::Nijie, Strategies::Twitter, Strategies::Tumblr, Strategies::Pawoo]
@@ -43,23 +43,6 @@ module Sources
       url
     end
 
-    def translated_tags
-      untranslated_tags = tags
-      untranslated_tags = untranslated_tags.map(&:first)
-      untranslated_tags += untranslated_tags.grep(/\//).map {|x| x.split(/\//)}.flatten
-      untranslated_tags = untranslated_tags.map do |tag|
-        if tag =~ /\A(\S+?)_?\d+users入り\Z/
-          $1
-        else
-          tag
-        end
-      end
-      untranslated_tags.reject! {|x| x.blank?}
-      wikis = WikiPage.title_in(untranslated_tags)
-      wikis += WikiPage.other_names_equal(untranslated_tags)
-      wikis.uniq.map{|wiki_page| [wiki_page.title, wiki_page.category_name]}
-    end
-
     def to_h
       return {
         :artist_name => artist_name,

app/logical/sources/strategies/base.rb

@@ -80,6 +80,23 @@ module Sources
         (@tags || []).uniq
       end
 
+      def translated_tags
+        translated_tags = tags.map(&:first).flat_map(&method(:translate_tag)).uniq.sort
+        translated_tags.map { |tag| [tag.name, tag.category] }
+      end
+
+      # Given a tag from the source site, should return an array of corresponding Danbooru tags.
+      def translate_tag(untranslated_tag)
+        translated_tags = Tag.where(name: WikiPage.active.other_names_equal([untranslated_tag]).uniq.select(:title))
+
+        if translated_tags.empty?
+          normalized_name = TagAlias.to_aliased([Tag.normalize_name(untranslated_tag)])
+          translated_tags = Tag.nonempty.where(name: normalized_name)
+        end
+
+        translated_tags
+      end
+
       # Should be set to a url for sites that prevent hotlinking, or left nil for sites that don't.
       def fake_referer
         nil

app/logical/sources/strategies/pixiv.rb

@@ -56,6 +56,17 @@ module Sources
         "http://www.pixiv.net/member.php?id=#{@metadata.user_id}/"
       end
 
+      def translate_tag(tag)
+        normalized_tag = tag.gsub(/\A(\S+?)_?\d+users入り\Z/i, '\1')
+
+        translated_tags = super(normalized_tag)
+        if translated_tags.empty? && normalized_tag.include?("/")
+          translated_tags = normalized_tag.split("/").flat_map { |tag| super(tag) }
+        end
+
+        translated_tags
+      end
+
       def get
         return unless illust_id_from_url
         @illust_id = illust_id_from_url