#99

backend/app/controllers/tags_controller.rb

@@ -37,7 +37,7 @@ class TagsController < ApplicationController
     q = q.where(posts: { id: post_id }) if post_id.present?
 
     q = q.where('tag_names.name LIKE ?', "%#{ name }%") if name
-    q = q.where(category: category) if category
+    q = q.where(category:) if category
     q = q.where('tags.post_count >= ?', post_count_between[0]) if post_count_between[0]
     q = q.where('tags.post_count <= ?', post_count_between[1]) if post_count_between[1]
     q = q.where('tags.created_at >= ?', created_between[0]) if created_between[0]
@@ -69,6 +69,38 @@ class TagsController < ApplicationController
     render json: { tags: TagRepr.base(tags), count: q.size }
   end
 
+  def with_depth
+    parent_tag_id = params[:parent].to_i
+    parent_tag_id = nil if parent_tag_id <= 0
+
+    tag_ids =
+        if parent_tag_id
+          TagImplication.where(parent_tag_id:).select(:tag_id)
+        else
+          Tag.where.not(id: TagImplication.select(:tag_id)).select(:id)
+        end
+
+    tags =
+        Tag
+        .joins(:tag_name)
+        .includes(:tag_name, tag_name: :wiki_page)
+        .where(id: tag_ids)
+        .order('tag_names.name')
+        .distinct
+        .to_a
+
+    has_children_tag_ids =
+        if tags.empty?
+          []
+        else
+          TagImplication.where(parent_tag_id: tags.map(&:id)).distinct.pluck(:parent_tag_id)
+        end
+
+    render json: tags.map { |tag|
+      TagRepr.base(tag).merge(has_children: has_children_tag_ids.include?(tag.id), children: [])
+    }
+  end
+
   def autocomplete
     q = params[:q].to_s.strip.sub(/\Anot:/i, '')