#434

backend/app/controllers/posts_controller.rb

@@ -449,24 +449,8 @@ class PostsController < ApplicationController
   private
 
   def tag_filter_references literals
-    raw = params[:tag_refs]
-    return nil if raw.blank?
-
-    references = JSON.parse(raw)
-    valid = references.is_a?(Array) && references.all? do |reference|
-      next false unless reference.is_a?(Hash) && reference['name'].is_a?(String)
-
-      ids = [reference['tag_id'], reference['external_tag_id']].compact
-      ((ids.any? || reference['missing'] == true) &&
-          ids.all? { _1.is_a?(Integer) && _1.positive? } &&
-          (!reference.key?('missing') || (reference['missing'] == true && ids.empty?)) &&
-          (!reference.key?('negative') || [true, false].include?(reference['negative'])))
-    end
-    raise ActionController::BadRequest unless valid
-    return nil unless references.map { _1['name'] } == literals
-
-    references
-  rescue JSON::ParserError, TypeError
+    PostTagSearch.parse_references(params[:tag_refs], literals)
+  rescue ArgumentError, JSON::ParserError, TypeError
     raise ActionController::BadRequest
   end
 
@@ -482,17 +466,7 @@ class PostsController < ApplicationController
 
   def filter_posts_by_tags locale, tag_names, match_type
     references = tag_filter_references(tag_names)
-    literals = tag_names.each_with_index.map do |raw_name, index|
-      name = raw_name.sub(/\Anot:/i, '')
-      name = TagName.canonicalise(locale, name).first unless references
-      reference = references&.[](index)
-      negative = if reference&.key?('negative')
-                   reference['negative']
-                 else
-                   raw_name.downcase.start_with?('not:')
-                 end
-      { name:, negative:, reference: }
-    end
+    literals = PostTagSearch.literals(locale, tag_names.join(' '), references:)
 
     return Post.all if literals.empty?
 
@@ -523,31 +497,10 @@ class PostsController < ApplicationController
   end
 
   def tagged_post_ids_for locale, name, reference: nil
-    if reference
-      matches = Post.none
-      if reference['tag_id']
-        matches = matches.or(Post.where(id: PostTag.where(
-            tag_id: reference['tag_id']).select(:post_id)))
-      end
-      if reference['external_tag_id']
-        matches = matches.or(Post.where(id: PostExternalTag.where(
-            external_tag_id: reference['external_tag_id']).select(:post_id)))
-      end
-      return matches.select(:id)
-    end
-
-    posts_by_internal_tags =
-        Post
-        .joins(tags: :tag_names)
-        .where(tag_names: { language_code: locale.language_code, name: })
-        .select(:id)
-
-    posts_by_external_tags =
-        Post
-        .joins(:external_tags)
-        .where("CONCAT(external_tags.platform, ':', external_tags.name) = ?", name)
-
-    (posts_by_internal_tags + posts_by_external_tags).uniq(&:id)
+    internal, external = PostTagSearch.references(locale, { name:, reference: })
+    Post.where(id: PostTag.where(tag_id: Array(internal)).select(:post_id))
+        .or(Post.where(id: PostExternalTag.where(external_tag_id: Array(external))
+            .select(:post_id))).select(:id)
   end
 
   def sync_post_tags! post, desired_tags, sections