FIX: TopicTimestampChanger should not allow timestamps in the future.

app/assets/javascripts/discourse/controllers/change-timestamp.js.es6

@@ -1,6 +1,7 @@
 import ModalFunctionality from 'discourse/mixins/modal-functionality';
 import computed from 'ember-addons/ember-computed-decorators';
 import DiscourseURL from 'discourse/lib/url';
+import Topic from 'discourse/models/topic';
 
 // Modal related to changing the timestamp of posts
 export default Ember.Controller.extend(ModalFunctionality, {
@@ -43,7 +44,7 @@ export default Ember.Controller.extend(ModalFunctionality, {
       const self = this,
             topic = this.get('topicController.model');
 
-      Discourse.Topic.changeTimestamp(
+      Topic.changeTimestamp(
         topic.get('id'),
         this.get('createdAt').unix()
       ).then(function() {

app/controllers/topics_controller.rb

@@ -560,11 +560,11 @@ class TopicsController < ApplicationController
     begin
       TopicTimestampChanger.new(
         topic_id: params[:topic_id].to_i,
-        timestamp: params[:timestamp].to_i
+        timestamp: params[:timestamp].to_f
       ).change!
 
       render json: success_json
-    rescue ActiveRecord::RecordInvalid
+    rescue ActiveRecord::RecordInvalid, TopicTimestampChanger::InvalidTimestampError
       render json: failed_json, status: 422
     end
   end

app/services/topic_timestamp_changer.rb

@@ -1,22 +1,27 @@
 class TopicTimestampChanger
-  def initialize(params)
+  class InvalidTimestampError < StandardError; end
-    @topic = params[:topic] || Topic.with_deleted.find(params[:topic_id])
+
+  def initialize(timestamp:, topic: nil, topic_id: nil)
+    @topic = topic || Topic.with_deleted.find(topic_id)
     @posts = @topic.posts
-    @timestamp = Time.at(params[:timestamp])
+    @current_timestamp = Time.zone.now
+    @timestamp = Time.zone.at(timestamp)
+
+    raise InvalidTimestampError if @timestamp.to_f > @current_timestamp.to_f
+
     @time_difference = calculate_time_difference
   end
 
   def change!
     ActiveRecord::Base.transaction do
       last_posted_at = @timestamp
-      now = Time.zone.now
 
       @posts.each do |post|
         if post.is_first_post?
           update_post(post, @timestamp)
         else
           new_created_at = Time.at(post.created_at.to_f + @time_difference)
-          new_created_at = now if new_created_at > now
+          new_created_at = @current_timestamp if new_created_at > @current_timestamp
           last_posted_at = new_created_at if new_created_at > last_posted_at
           update_post(post, new_created_at)
         end

spec/services/topic_timestamp_changer_spec.rb

@@ -4,53 +4,60 @@ describe TopicTimestampChanger do
   describe "change!" do
     let(:old_timestamp) { Time.zone.now }
     let(:new_timestamp) { old_timestamp + 1.day }
-    let!(:topic) { Fabricate(:topic, created_at: old_timestamp) }
+    let(:topic) { Fabricate(:topic, created_at: old_timestamp) }
     let!(:p1) { Fabricate(:post, topic: topic, created_at: old_timestamp) }
     let!(:p2) { Fabricate(:post, topic: topic, created_at: old_timestamp + 1.day) }
-    let(:params) { { topic_id: topic.id, timestamp: new_timestamp.to_f } }
 
     context 'new timestamp is in the future' do
       let(:new_timestamp) { old_timestamp + 2.day }
 
+      it 'should raise the right error' do
+        expect { TopicTimestampChanger.new(topic: topic, timestamp: new_timestamp.to_f).change! }
+          .to raise_error(TopicTimestampChanger::InvalidTimestampError)
+      end
+    end
+
+    context 'new timestamp is in the past' do
+      let(:new_timestamp) { old_timestamp - 2.day }
+
       it 'changes the timestamp of the topic and opening post' do
         Timecop.freeze do
-          TopicTimestampChanger.new(params).change!
+          TopicTimestampChanger.new(topic: topic, timestamp: new_timestamp.to_f).change!
 
           topic.reload
           [:created_at, :updated_at, :bumped_at].each do |column|
-            expect(topic.public_send(column)).to be_within_one_second_of(new_timestamp)
+            expect(topic.public_send(column)).to be_within(1.second).of(new_timestamp)
           end
 
           p1.reload
           [:created_at, :updated_at].each do |column|
-            expect(p1.public_send(column)).to be_within_one_second_of(new_timestamp)
+            expect(p1.public_send(column)).to be_within(1.second).of(new_timestamp)
           end
 
-          expect(topic.last_posted_at).to be_within_one_second_of(p2.reload.created_at)
-        end
-      end
-    end
-
-    describe 'predated timestamp' do
-      it 'updates the timestamp of posts in the topic with the time difference applied' do
-        TopicTimestampChanger.new(params).change!
-
           p2.reload
           [:created_at, :updated_at].each do |column|
-          expect(p2.public_send(column)).to be_within_one_second_of(old_timestamp + 2.day)
+            expect(p2.public_send(column)).to be_within(1.second).of(new_timestamp + 1.day)
           end
+
+          expect(topic.last_posted_at).to be_within(1.second).of(p2.reload.created_at)
         end
       end
 
-    describe 'backdated timestamp' do
+      describe 'when posts have timestamps in the future' do
-      let(:new_timestamp) { old_timestamp - 1.day }
+        let(:new_timestamp) { Time.zone.now }
+        let(:p3) { Fabricate(:post, topic: topic, created_at: new_timestamp + 3.day) }
 
-      it 'updates the timestamp of posts in the topic with the time difference applied' do
+        it 'should set the new timestamp as the default timestamp' do
-        TopicTimestampChanger.new(params).change!
+          Timecop.freeze do
+            p3
+            TopicTimestampChanger.new(topic: topic, timestamp: new_timestamp.to_f).change!
+
+            p3.reload
 
-        p2.reload
             [:created_at, :updated_at].each do |column|
-          expect(p2.public_send(column)).to be_within_one_second_of(old_timestamp)
+              expect(p3.public_send(column)).to be_within(1.second).of(new_timestamp)
+            end
+          end
         end
       end
     end
@@ -59,7 +66,7 @@ describe TopicTimestampChanger do
       $redis.set AdminDashboardData.stats_cache_key, "X"
       $redis.set About.stats_cache_key, "X"
 
-      TopicTimestampChanger.new(params).change!
+      TopicTimestampChanger.new(topic: topic, timestamp: Time.zone.now.to_f).change!
 
       expect($redis.get(AdminDashboardData.stats_cache_key)).to eq(nil)
       expect($redis.get(About.stats_cache_key)).to eq(nil)