DEV: Add post_id parameter to reset_bump_date route (#25372)

This would allow a theme component (or an API call) to reset the bump
date of a topic to a given post's created_at date.

I picked `post_id` as the parameter here because it provides a bit of
extra protection against accidentally resetting the bump date to a date
that doesn't make sense.

app/controllers/topics_controller.rb

@@ -1151,12 +1151,14 @@ class TopicsController < ApplicationController
 
   def reset_bump_date
     params.require(:id)
+    params.permit(:post_id)
+
     guardian.ensure_can_update_bumped_at!
 
     topic = Topic.find_by(id: params[:id])
     raise Discourse::NotFound.new unless topic
 
-    topic.reset_bumped_at
+    topic.reset_bumped_at(params[:post_id])
     render body: nil
   end
 

app/models/topic.rb

@@ -1858,13 +1858,21 @@ class Topic < ActiveRecord::Base
     @is_category_topic ||= Category.exists?(topic_id: self.id.to_i)
   end
 
-  def reset_bumped_at
+  def reset_bumped_at(post_id = nil)
     post =
-      ordered_posts.where(
+      (
-        user_deleted: false,
+        if post_id
-        hidden: false,
+          Post.find_by(id: post_id)
-        post_type: Post.types[:regular],
+        else
-      ).last || first_post
+          ordered_posts.where(
+            user_deleted: false,
+            hidden: false,
+            post_type: Post.types[:regular],
+          ).last || first_post
+        end
+      )
+
+    return if !post
 
     self.bumped_at = post.created_at
     self.save(validate: false)

config/routes.rb

@@ -1237,7 +1237,11 @@ Discourse::Application.routes.draw do
     put "t/:id/convert-topic/:type" => "topics#convert_topic"
     put "t/:id/publish" => "topics#publish"
     put "t/:id/shared-draft" => "topics#update_shared_draft"
-    put "t/:id/reset-bump-date" => "topics#reset_bump_date"
+    put "t/:id/reset-bump-date/(:post_id)" => "topics#reset_bump_date",
+        :constraints => {
+          id: /\d+/,
+          post_id: /\d+/,
+        }
     put "topics/bulk"
     put "topics/reset-new" => "topics#reset_new"
     put "topics/pm-reset-new" => "topics#private_message_reset_new"

spec/requests/topics_controller_spec.rb

@@ -5298,6 +5298,28 @@ RSpec.describe TopicsController do
         expect(topic.reload.bumped_at).to eq_time(timestamp)
       end
     end
+
+    context "with a post_id parameter" do
+      before { sign_in(admin) }
+
+      it "resets bump correctly" do
+        post1 = Fabricate(:post, user: post_author1, topic: topic, created_at: 2.days.ago)
+        post2 = Fabricate(:post, user: post_author1, topic: topic, created_at: 1.day.ago)
+
+        put "/t/#{topic.id}/reset-bump-date/#{post1.id}.json"
+        expect(response.status).to eq(200)
+        expect(topic.reload.bumped_at).to eq_time(post1.created_at)
+      end
+
+      it "does not raise an error for an inexistent post" do
+        id = (SecureRandom.random_number * 100_000_000).to_i
+        original_bumped_at = topic.bumped_at
+
+        put "/t/#{topic.id}/reset-bump-date/#{id}.json"
+        expect(response.status).to eq(200)
+        expect(topic.reload.bumped_at).to eq_time(original_bumped_at)
+      end
+    end
   end
 
   describe "#private_message_reset_new" do