FEATURE: Custom content summarization strategies. (#21813)

* FEATURE: Content custom summarization strategies.

This PR establishes a pattern for plugins to register alternative ways of summarizing content by extending a class that defines an interface.

Core controls which strategy we'll use and who has access to it through the `summarization_strategy` and `custom_summarization_allowed_groups`. It also defines the UI for summarizing topics.

Other plugins can access this summarization mechanism and implement their features, removing cross-plugin customizations, as it currently happens between chat and the discourse-ai plugin.

* Group membership validation and rate limiting

* Work with objects instead of classes

* Port summarization feature from discourse-ai to chat

* Rename available summaries to 'Top Replies' and 'Summary'

config/locales/client.en.yml

@@ -2054,10 +2054,13 @@ en:
           other {# minutes}
         }</b>.
 
-      enable: "Summarize This Topic"
+      enable: "Show top replies"
       disable: "Show All Posts"
       short_label: "Summarize"
       short_title: "Show a summary of this topic: the most interesting posts as determined by the community"
+      strategy: 
+        button_title: "Summarize this topic"
+        title: "Topic summary"
 
     deleted_filter:
       enabled_description: "This topic contains deleted posts, which have been hidden."

config/locales/server.en.yml

@@ -1600,6 +1600,8 @@ en:
     summary_percent_filter: "When a user clicks 'Summarize This Topic', show the top % of posts"
     summary_max_results: "Maximum posts returned by 'Summarize This Topic'"
     summary_timeline_button: "Show a 'Summarize' button in the timeline"
+    summarization_strategy: "Additional ways to summarize content registered by plugins"
+    custom_summarization_allowed_groups: "Groups allowed to summarize contents using the `summarization_strategy`."
 
     enable_personal_messages: "DEPRECATED, use the 'personal message enabled groups' setting instead. Allow trust level 1 (configurable via min trust to send messages) users to create messages and reply to messages. Note that staff can always send messages no matter what."
     personal_message_enabled_groups: "Allow users within these groups to create messages and reply to messages. Trust level groups include all trust levels above that number, for example choosing trust_level_1 also allows trust_level_2, 3, 4 users to send PMs. Note that staff can always send messages no matter what."

config/routes.rb

@@ -1319,6 +1319,11 @@ Discourse::Application.routes.draw do
           topic_id: /\d+/,
         }
     get "t/:topic_id/summary" => "topics#show", :constraints => { topic_id: /\d+/ }
+    get "t/:topic_id/strategy-summary" => "topics#summary",
+        :constraints => {
+          topic_id: /\d+/,
+        },
+        :format => :json
     put "t/:slug/:topic_id" => "topics#update", :constraints => { topic_id: /\d+/ }
     put "t/:slug/:topic_id/star" => "topics#star", :constraints => { topic_id: /\d+/ }
     put "t/:topic_id/star" => "topics#star", :constraints => { topic_id: /\d+/ }

config/site_settings.yml

@@ -2351,6 +2351,17 @@ uncategorized:
     client: true
     default: false
 
+  summarization_strategy:
+    client: true
+    default: ""
+    enum: "SummarizationStrategy"
+    validator: "SummarizationValidator"
+  custom_summarization_allowed_groups:
+    client: true
+    type: group_list
+    list_type: compact
+    default: "3|14" # 3: @staff, 14: @trust_level_4
+
   automatic_topic_heat_values: true
 
   # View heat thresholds