search: move misc search parsing helpers to PostQueryBuilder.

* Move various search parser helper methods (`has_metatag?`,
  `is_single_tag?` et al) from PostSets and the Tag model to
  PostQueryBuilder.

* Fix various minor bugs stemming from trying to check if a search query
  contains certain metatags using regexes or other adhoc techniques.

app/helpers/posts_helper.rb

@@ -15,7 +15,7 @@ module PostsHelper
 
   def missed_post_search_count_js
     return unless post_search_counts_enabled?
-    return unless params[:ms] == "1" && @post_set.post_count == 0 && @post_set.is_single_tag?
+    return unless params[:ms] == "1" && @post_set.post_count == 0 && @post_set.query.is_single_term?
 
     sig = generate_reportbooru_signature(params[:tags])
     render "posts/partials/index/missed_search_count", sig: sig

app/logical/post_query_builder.rb

@@ -761,7 +761,7 @@ class PostQueryBuilder
 
           terms << OpenStruct.new({ type: :metatag, name: metatag.downcase, value: value })
         elsif scanner.scan(/[^ ]+/)
-          terms << OpenStruct.new({ type: :tag, value: scanner.matched.downcase })
+          terms << OpenStruct.new({ type: :tag, name: scanner.matched.downcase })
         end
       end
 
@@ -775,7 +775,7 @@ class PostQueryBuilder
         elsif term.type == :metatag
           "#{term.name}:#{term.value}"
         elsif term.type == :tag
-          term.value
+          term.name
         end
       end
     end
@@ -1097,7 +1097,7 @@ class PostQueryBuilder
           end
 
         else
-          parse_tag(term.value, q[:tags])
+          parse_tag(term.name, q[:tags])
         end
       end
 
@@ -1254,5 +1254,52 @@ class PostQueryBuilder
     end
   end
 
+  concerning :UtilityMethods do
+    def tags
+      scan_query.select { |term| term.type == :tag }
+    end
+
+    def metatags
+      scan_query.select { |term| term.type == :metatag }
+    end
+
+    def find_metatag(metatag)
+      metatags.find { |term| term.name == metatag.to_s.downcase }.try(:value)
+    end
+
+    def has_metatag?(*metatag_names)
+      metatags.any? { |term| term.name.in?(metatag_names.map(&:to_s).map(&:downcase)) }
+    end
+
+    def is_metatag?(name, value = nil)
+      if value.nil?
+        is_single_term? && has_metatag?(name)
+      else
+        is_single_term? && find_metatag(name) == value.to_s
+      end
+    end
+
+    def is_empty_search?
+      scan_query.size == 0
+    end
+
+    def is_single_term?
+      scan_query.size == 1
+    end
+
+    def is_single_tag?
+      is_single_term? && tags.size == 1
+    end
+
+    def is_simple_tag?
+      tag = tags.first&.name
+      is_single_tag? && !tag.starts_with?("-") && !tag.starts_with?("~") && !tag.include?("*")
+    end
+
+    def is_wildcard_search?
+      is_single_tag? && tags.first.name.include?("*")
+    end
+  end
+
   memoize :scan_query, :split_query, :parse_query
 end

app/logical/post_sets/post.rb

@@ -1,10 +1,11 @@
 module PostSets
   class Post
     MAX_PER_PAGE = 200
-    attr_reader :tag_array, :page, :raw, :random, :post_count, :format
+    attr_reader :page, :raw, :random, :post_count, :format, :tag_string, :query
 
     def initialize(tags, page = 1, per_page = nil, raw: false, random: false, format: "html")
-      @tag_array = PostQueryBuilder.new(tags).split_query
+      @query = PostQueryBuilder.new(tags)
+      @tag_string = tags
       @page = page
       @per_page = per_page
       @raw = raw.to_s.truthy?
@@ -12,12 +13,8 @@ module PostSets
       @format = format.to_s
     end
 
-    def tag_string
-      @tag_string ||= tag_array.uniq.join(" ")
-    end
-
     def humanized_tag_string
-      tag_array.map { |tag| tag.tr("_", " ").titleize }.to_sentence
+      query.split_query.map { |tag| tag.tr("_", " ").titleize }.to_sentence
     end
 
     def has_blank_wiki?
@@ -31,8 +28,8 @@ module PostSets
     end
 
     def tag
-      return nil if !is_single_tag?
-      @tag ||= Tag.find_by(name: Tag.normalize_name(tag_string))
+      return nil unless query.is_simple_tag?
+      @tag ||= Tag.find_by(name: query.tags.first.name)
     end
 
     def artist
@@ -42,15 +39,15 @@ module PostSets
     end
 
     def pool
-      name = Tag.has_metatag?(tag_array, :ordpool, :pool)
-      return nil unless is_single_tag? && name.present?
+      return nil unless query.is_metatag?(:pool) || query.is_metatag?(:ordpool)
+      name = query.find_metatag(:pool) || query.find_metatag(:ordpool)
 
       @pool ||= Pool.find_by_name(name)
     end
 
     def favgroup
-      name = Tag.has_metatag?(tag_array, :favgroup)
-      return nil unless is_single_tag? && name.present?
+      return nil unless query.is_metatag?(:favgroup)
+      name = query.find_metatag(:favgroup)
 
       @favgroup ||= FavoriteGroup.visible(CurrentUser.user).find_by_name_or_id(name, CurrentUser.user)
     end
@@ -76,11 +73,11 @@ module PostSets
     end
 
     def per_page
-      (@per_page || Tag.has_metatag?(tag_array, :limit) || CurrentUser.user.per_page).to_i.clamp(0, MAX_PER_PAGE)
+      (@per_page || query.find_metatag(:limit) || CurrentUser.user.per_page).to_i.clamp(0, MAX_PER_PAGE)
     end
 
     def is_random?
-      random || Tag.has_metatag?(tag_array, :order) == "random"
+      random || query.find_metatag(:order) == "random"
     end
 
     def get_post_count
@@ -118,34 +115,14 @@ module PostSets
 
     def hide_from_crawler?
       return true if current_page > 1
-      return false if is_empty_tag? || is_simple_tag? || tag_string == "order:rank"
+      return false if query.is_empty_search? || query.is_simple_tag? || query.is_metatag?(:order, :rank)
       true
     end
 
-    def is_single_tag?
-      tag_array.size == 1
-    end
-
-    def is_simple_tag?
-      Tag.is_simple_tag?(tag_string)
-    end
-
-    def is_empty_tag?
-      tag_array.empty?
-    end
-
-    def is_pattern_search?
-      is_single_tag? && tag_string =~ /\*/ && tag_array.none? {|x| x =~ /^-?source:.+/}
-    end
-
     def current_page
       [page.to_i, 1].max
     end
 
-    def is_saved_search?
-      tag_string =~ /search:/
-    end
-
     def presenter
       @presenter ||= ::PostSetPresenters::Post.new(self)
     end

app/logical/related_tag_query.rb

@@ -56,7 +56,7 @@ class RelatedTagQuery
 
     versions = PostVersion.where(updater_id: user.id).where("updated_at > ?", since).order(id: :desc).limit(max_edits)
     tags = versions.flat_map(&:added_tags)
-    tags = tags.reject { |tag| Tag.is_metatag?(tag) }
+    tags = tags.select { |tag| PostQueryBuilder.new(tag).is_simple_tag? }
     tags = tags.group_by(&:itself).transform_values(&:size).sort_by { |tag, count| [-count, tag] }.map(&:first)
     tags.take(max_tags)
   end

app/models/post.rb

@@ -1069,7 +1069,7 @@ class Post < ApplicationRecord
     def fast_count(tags = "", timeout: 1_000, raise_on_timeout: false, skip_cache: false)
       tags = tags.to_s
       tags += " rating:s" if CurrentUser.safe_mode?
-      tags += " -status:deleted" if CurrentUser.hide_deleted_posts? && !Tag.has_metatag?(tags, "status", "-status")
+      tags += " -status:deleted" if CurrentUser.hide_deleted_posts? && !PostQueryBuilder.new(tags).has_metatag?("status", "-status")
       tags = PostQueryBuilder.new(tags).normalize_query
 
       # Optimize some cases. these are just estimates but at these
@@ -1135,7 +1135,7 @@ class Post < ApplicationRecord
     end
 
     def get_count_from_cache(tags)
-      if Tag.is_simple_tag?(tags)
+      if PostQueryBuilder.new(tags).is_simple_tag?
         count = Tag.find_by(name: tags).try(:post_count)
       else
         # this will only have a value for multi-tag searches or single metatag searches

app/models/tag.rb

@@ -227,40 +227,6 @@ class Tag < ApplicationRecord
     end
   end
 
-  module ParseMethods
-    # true if query is a single "simple" tag (not a metatag, negated tag, or wildcard tag).
-    def is_simple_tag?(query)
-      is_single_tag?(query) && !is_metatag?(query) && !is_negated_tag?(query) && !is_optional_tag?(query) && !is_wildcard_tag?(query)
-    end
-
-    def is_single_tag?(query)
-      PostQueryBuilder.new(query).split_query.size == 1
-    end
-
-    def is_metatag?(tag)
-      has_metatag?(tag, *PostQueryBuilder::METATAGS)
-    end
-
-    def is_negated_tag?(tag)
-      tag.starts_with?("-")
-    end
-
-    def is_optional_tag?(tag)
-      tag.starts_with?("~")
-    end
-
-    def is_wildcard_tag?(tag)
-      tag.include?("*")
-    end
-
-    def has_metatag?(tags, *metatags)
-      return nil if tags.blank?
-
-      tags = PostQueryBuilder.new(tags.to_str).split_query if tags.respond_to?(:to_str)
-      tags.grep(/\A(?:#{metatags.map(&:to_s).join("|")}):(.+)\z/i) { $1 }.first
-    end
-  end
-
   module SearchMethods
     # ref: https://www.postgresql.org/docs/current/static/pgtrgm.html#idm46428634524336
     def order_similarity(name)
@@ -393,6 +359,5 @@ class Tag < ApplicationRecord
   include ApiMethods
   include CountMethods
   include CategoryMethods
-  extend ParseMethods
   extend SearchMethods
 end

app/models/upload.rb

@@ -237,7 +237,7 @@ class Upload < ApplicationRecord
   include SourceMethods
 
   def assign_rating_from_tags
-    if rating = Tag.has_metatag?(tag_string, :rating)
+    if rating = PostQueryBuilder.new(tag_string).find_metatag(:rating)
       self.rating = rating.downcase.first
     end
   end

app/presenters/post_presenter.rb

@@ -163,7 +163,7 @@ class PostPresenter
   end
 
   def has_sequential_navigation?(params)
-    return false if Tag.has_metatag?(params[:q], :order, :ordfav, :ordpool)
+    return false if PostQueryBuilder.new(params[:q]).has_metatag?(:order, :ordfav, :ordpool)
     return false if params[:pool_id].present? || params[:favgroup_id].present?
     return CurrentUser.user.enable_sequential_post_navigation
   end

app/presenters/post_set_presenters/post.rb

@@ -18,13 +18,13 @@ module PostSetPresenters
     end
 
     def related_tags
-      if post_set.is_pattern_search?
-        pattern_tags
-      elsif post_set.is_saved_search?
+      if post_set.query.is_wildcard_search?
+        wildcard_tags
+      elsif post_set.query.is_metatag?(:search)
         saved_search_tags
-      elsif post_set.is_empty_tag? || post_set.tag_string == "order:rank"
+      elsif post_set.query.is_empty_search? || post_set.query.is_metatag?(:order, :rank)
         popular_tags
-      elsif post_set.is_single_tag?
+      elsif post_set.query.is_single_term?
         similar_tags
       else
         frequent_tags
@@ -47,7 +47,7 @@ module PostSetPresenters
       RelatedTagCalculator.frequent_tags_for_post_array(post_set.posts).take(MAX_TAGS)
     end
 
-    def pattern_tags
+    def wildcard_tags
       Tag.wildcard_matches(post_set.tag_string)
     end
 
@@ -56,7 +56,7 @@ module PostSetPresenters
     end
 
     def tag_list_html(**options)
-      tag_set_presenter.tag_list_html(name_only: post_set.is_saved_search?, **options)
+      tag_set_presenter.tag_list_html(name_only: post_set.query.is_metatag?(:search), **options)
     end
   end
 end

app/views/posts/index.html.erb

@@ -19,7 +19,7 @@
 
   <%= render "posts/partials/index/options" %>
 
-  <%= render "posts/partials/index/related" %>
+  <%= render "posts/partials/index/related", post_set: @post_set %>
 <% end %>
 
 <% content_for(:content) do %>

app/views/posts/partials/index/_related.html.erb

@@ -15,7 +15,7 @@
 
     <li><%= link_to "Deleted", posts_path(tags: "#{params[:tags]} status:deleted") %></li>
     <li><%= link_to "Random", random_posts_path(tags: params[:tags]), id: "random-post", "data-shortcut": "r" %></li>
-    <% if Tag.is_simple_tag?(params[:tags]) %>
+    <% if post_set.query.is_simple_tag? %>
       <li><%= link_to "History", post_versions_path(search: { changed_tags: params[:tags] }) %></li>
     <% end %>
     <li><%= link_to "Count", posts_counts_path(:tags => params[:tags]) %></li>

app/views/posts/partials/index/_seo_meta_tags.html.erb

@@ -1,4 +1,4 @@
-<% if @post_set.is_empty_tag? %>
+<% if @post_set.query.is_empty_search? %>
   <% page_title("#{Danbooru.config.app_name}: Anime Image Board", suffix: nil) %>
   <% meta_description("#{Danbooru.config.canonical_app_name} is the original anime image 'booru. Find over 3.75 million anime pictures categorized by over 100 million tags.") %>