FEATURE: Backfill task for sentiment module (#316)

* FEATURE: Backfill task for sentiment module

* fix join clause

lib/tasks/modules/sentiment/backfill.rake

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+desc "Backfill sentiment for all posts"
+task "ai:sentiment:backfill", [:start_post] => [:environment] do |_, args|
+  public_categories = Category.where(read_restricted: false).pluck(:id)
+
+  Post
+    .joins("INNER JOIN topics ON topics.id = posts.topic_id")
+    .joins(
+      "LEFT JOIN classification_results ON classification_results.target_id = posts.id AND classification_results.target_type = 'Post'",
+    )
+    .where("classification_results.target_id IS NULL")
+    .where("posts.id >= ?", args[:start_post].to_i || 0)
+    .where("category_id IN (?)", public_categories)
+    .where(posts: { deleted_at: nil })
+    .order("posts.id ASC")
+    .find_each do |post|
+      print "."
+      DiscourseAi::PostClassificator.new(
+        DiscourseAi::Sentiment::SentimentClassification.new,
+      ).classify!(post)
+    end
+end