FEATURE: search_rank_sort_priorities modifier (#21329)

This new modifier can be used by plugins to modify search ordering.

Specifically plugins such as discourse_solved can amend search ordering
so solved topics bump to the top.

Also correct edge case where low and high sort priority categories did not
order correctly when it came to closed/archived

lib/search.rb

@@ -1153,20 +1153,28 @@ class Search
         )
         SQL
 
+        rank_sort_priorities = [["topics.archived", 0.85], ["topics.closed", 0.9]]
+
+        rank_sort_priorities =
+          DiscoursePluginRegistry.apply_modifier(
+            :search_rank_sort_priorities,
+            rank_sort_priorities,
+            self,
+          )
+
         category_priority_weights = <<~SQL
           (
             CASE categories.search_priority
               WHEN #{Searchable::PRIORITIES[:low]}
-          THEN #{SiteSetting.category_search_priority_low_weight}
+              THEN #{SiteSetting.category_search_priority_low_weight.to_f}
               WHEN #{Searchable::PRIORITIES[:high]}
-          THEN #{SiteSetting.category_search_priority_high_weight}
-          ELSE
-            CASE WHEN topics.archived
-            THEN 0.85
-            WHEN topics.closed
-            THEN 0.9
-            ELSE 1
+              THEN #{SiteSetting.category_search_priority_high_weight.to_f}
+              ELSE 1.0
             END
+            *
+            CASE
+              #{rank_sort_priorities.sort_by { |_, pri| -pri }.map { |k, v| "WHEN #{k} THEN #{v}" }.join("\n")}
+              ELSE 1.0
             END
           )
         SQL
@@ -1302,8 +1310,6 @@ class Search
   end
 
   def aggregate_post_sql(opts)
-    default_opts = { type_filter: opts[:type_filter] }
-
     min_id =
       if SiteSetting.search_recent_regular_posts_offset_post_id > 0
         if %w[all_topics private_message].include?(opts[:type_filter])

spec/lib/search_spec.rb

@@ -2654,6 +2654,34 @@ RSpec.describe Search do
     end
   end
 
+  context "when plugin introduces a search_rank_sort_priorities modifier" do
+    before do
+      SearchIndexer.enable
+      DiscoursePluginRegistry.clear_modifiers!
+    end
+    after do
+      SearchIndexer.disable
+
+      DiscoursePluginRegistry.clear_modifiers!
+    end
+
+    it "allow modifying the search rank" do
+      plugin = Plugin::Instance.new
+      plugin.register_modifier(:search_rank_sort_priorities) do |ranks, search|
+        [["topics.closed", 77]]
+      end
+
+      closed_topic = Fabricate(:topic, title: "saml saml saml is the best", closed: true)
+      closed_post = Fabricate(:post, topic: closed_topic, raw: "this topic is a story about saml")
+
+      open_topic = Fabricate(:topic, title: "saml saml saml is the best2")
+      open_post = Fabricate(:post, topic: open_topic, raw: "this topic is a story about saml")
+
+      result = Search.execute("story")
+      expect(result.posts.pluck(:id)).to eq([closed_post.id, open_post.id])
+    end
+  end
+
   context "when max_duplicate_search_index_terms limits duplication" do
     before { SearchIndexer.enable }