search: add comment_count, note_count metatags (#4004).

Add these metatags:

* comment_count
* deleted_comment_count
* active_comment_count
* note_count
* deleted_note_count
* active_note_count
* order:comment_count
* order:deleted_comment_count
* order:active_comment_count
* order:note_count
* order:deleted_note_count
* order:active_note_count

app/logical/post_query_builder.rb

@@ -85,6 +85,28 @@ class PostQueryBuilder
     relation
   end
 
+  def table_for_metatag(metatag)
+    if metatag.in?(Tag::COUNT_METATAGS)
+      metatag[/(?<table>[a-z]+)_count\z/i, :table]
+    else
+      nil
+    end
+  end
+
+  def tables_for_query(q)
+    metatags = q.keys
+    metatags << q[:order].remove(/_(asc|desc)\z/i) if q[:order].present?
+
+    tables = metatags.map { |metatag| table_for_metatag(metatag.to_s) }
+    tables.compact.uniq
+  end
+
+  def add_joins(q, relation)
+    tables = tables_for_query(q)
+    relation = relation.with_stats(tables)
+    relation
+  end
+
   def hide_deleted_posts?(q)
     return false if CurrentUser.admin_mode?
     return false if q[:status].in?(%w[deleted active any all])
@@ -107,6 +129,7 @@ class PostQueryBuilder
       relation = relation.where("posts.rating = 's'")
     end
 
+    relation = add_joins(q, relation)
     relation = add_range_relation(q[:post_id], "posts.id", relation)
     relation = add_range_relation(q[:mpixels], "posts.image_width * posts.image_height / 1000000.0", relation)
     relation = add_range_relation(q[:ratio], "ROUND(1.0 * posts.image_width / GREATEST(1, posts.image_height), 2)", relation)
@@ -122,6 +145,10 @@ class PostQueryBuilder
     end
     relation = add_range_relation(q[:post_tag_count], "posts.tag_count", relation)
 
+    Tag::COUNT_METATAGS.each do |column|
+      relation = add_range_relation(q[column.to_sym], "posts.#{column}", relation)
+    end
+
     if q[:md5]
       relation = relation.where("posts.md5": q[:md5])
     end
@@ -544,6 +571,11 @@ class PostQueryBuilder
     when "filesize_asc"
       relation = relation.order("posts.file_size ASC")
 
+    when /\A(?<column>#{Tag::COUNT_METATAGS.join("|")})(_(?<direction>asc|desc))?\z/i
+      column = $~[:column]
+      direction = $~[:direction] || "desc"
+      relation = relation.order(column => direction, :id => direction)
+
     when "tagcount", "tagcount_desc"
       relation = relation.order("posts.tag_count DESC")
 

app/models/post.rb

@@ -1609,6 +1609,33 @@ class Post < ApplicationRecord
       joins("CROSS JOIN unnest(string_to_array(tag_string, ' ')) AS tag")
     end
 
+    def with_comment_stats
+      relation = left_outer_joins(:comments).group(:id).select("posts.*")
+      relation = relation.select("COUNT(comments.id) AS comment_count")
+      relation = relation.select("COUNT(comments.id) FILTER (WHERE comments.is_deleted = TRUE)  AS deleted_comment_count")
+      relation = relation.select("COUNT(comments.id) FILTER (WHERE comments.is_deleted = FALSE) AS active_comment_count")
+      relation
+    end
+
+    def with_note_stats
+      relation = left_outer_joins(:notes).group(:id).select("posts.*")
+      relation = relation.select("COUNT(notes.id) AS note_count")
+      relation = relation.select("COUNT(notes.id) FILTER (WHERE notes.is_active = TRUE)  AS active_note_count")
+      relation = relation.select("COUNT(notes.id) FILTER (WHERE notes.is_active = FALSE) AS deleted_note_count")
+      relation
+    end
+
+    def with_stats(tables)
+      return all if tables.empty?
+
+      relation = all
+      tables.each do |table|
+        relation = relation.send("with_#{table}_stats")
+      end
+
+      from(relation.arel.as("posts"))
+    end
+
     def pending
       where(is_pending: true)
     end

app/models/tag.rb

@@ -1,5 +1,9 @@
 class Tag < ApplicationRecord
   COSINE_SIMILARITY_RELATED_TAG_THRESHOLD = 300
+  COUNT_METATAGS = %w[
+    comment_count deleted_comment_count active_comment_count
+    note_count deleted_note_count active_note_count
+  ]
   METATAGS = %w[
     -user user -approver approver commenter comm noter noteupdater artcomm
     -pool pool ordpool -favgroup favgroup -fav fav ordfav md5 -rating rating
@@ -7,7 +11,7 @@ class Tag < ApplicationRecord
     -source id -id date age order limit -status status tagcount parent -parent
     child pixiv_id pixiv search upvote downvote filetype -filetype flagger
     -flagger appealer -appealer disapproval -disapproval
-  ] + TagCategory.short_name_list.map {|x| "#{x}tags"}
+  ] + TagCategory.short_name_list.map {|x| "#{x}tags"} + COUNT_METATAGS
 
   SUBQUERY_METATAGS = %w[commenter comm noter noteupdater artcomm flagger -flagger appealer -appealer]
 
@@ -790,6 +794,9 @@ class Tag < ApplicationRecord
               q[:downvote] = User.name_to_id(g2)
             end
 
+          when *COUNT_METATAGS
+            q[g1.to_sym] = parse_helper(g2)
+
           end
 
         else

test/unit/post_test.rb

@@ -2103,6 +2103,16 @@ class PostTest < ActiveSupport::TestCase
       assert_tag_match([posts[1]], "noter:none")
     end
 
+    should "return posts for the note_count:<N> metatag" do
+      posts = FactoryBot.create_list(:post, 3)
+      FactoryBot.create(:note, post: posts[0], is_active: true)
+      FactoryBot.create(:note, post: posts[1], is_active: false)
+
+      assert_tag_match([posts[1], posts[0]], "note_count:1")
+      assert_tag_match([posts[0]], "active_note_count:1")
+      assert_tag_match([posts[1]], "deleted_note_count:1")
+    end
+
     should "return posts for the artcomm:<name> metatag" do
       users = FactoryBot.create_list(:user, 2)
       posts = FactoryBot.create_list(:post, 2)
@@ -2387,6 +2397,8 @@ class PostTest < ActiveSupport::TestCase
         p
       end
 
+      FactoryBot.create(:note, post: posts.second)
+
       assert_tag_match(posts.reverse, "order:id_desc")
       assert_tag_match(posts.reverse, "order:score")
       assert_tag_match(posts.reverse, "order:favcount")
@@ -2404,6 +2416,8 @@ class PostTest < ActiveSupport::TestCase
       assert_tag_match(posts.reverse, "order:chartags")
       assert_tag_match(posts.reverse, "order:copytags")
       assert_tag_match(posts.reverse, "order:rank")
+      assert_tag_match(posts.reverse, "order:note_count")
+      assert_tag_match(posts.reverse, "order:note_count_desc")
 
       assert_tag_match(posts, "order:id_asc")
       assert_tag_match(posts, "order:score_asc")
@@ -2421,6 +2435,7 @@ class PostTest < ActiveSupport::TestCase
       assert_tag_match(posts, "order:arttags_asc")
       assert_tag_match(posts, "order:chartags_asc")
       assert_tag_match(posts, "order:copytags_asc")
+      assert_tag_match(posts, "order:note_count_asc")
     end
 
     should "return posts for order:comment_bumped" do