UX: Update topics stats automatically (#17135)

Updates automatically data on the stats section of the topic.

It will update automatically the following information: likes, replies and last reply (timestamp and user)

app/assets/javascripts/discourse/app/controllers/topic.js

@@ -1700,6 +1700,30 @@ export default Controller.extend(bufferedProperty("model"), {
             topic.set("message_archived", true);
             break;
           }
+          case "stats": {
+            let updateStream = false;
+            ["last_posted_at", "like_count", "posts_count"].forEach(
+              (property) => {
+                const value = data[property];
+                if (typeof value !== "undefined") {
+                  topic.set(property, value);
+                  updateStream = true;
+                }
+              }
+            );
+
+            if (data["last_poster"]) {
+              topic.details.set("last_poster", data["last_poster"]);
+              updateStream = true;
+            }
+
+            if (updateStream) {
+              postStream
+                .triggerChangedTopicStats()
+                .then((firstPostId) => refresh({ id: firstPostId }));
+            }
+            break;
+          }
           default: {
             let callback = customPostMessageCallbacks[data.type];
             if (callback) {

app/assets/javascripts/discourse/app/models/post-stream.js

@@ -872,6 +872,17 @@ export default RestModel.extend({
     return resolved;
   },
 
+  triggerChangedTopicStats() {
+    if (this.firstPostNotLoaded) {
+      return Promise.reject();
+    }
+
+    return Promise.resolve().then(() => {
+      const firstPost = this.posts.findBy("post_number", 1);
+      return firstPost.id;
+    });
+  },
+
   postForPostNumber(postNumber) {
     if (!this.hasPosts) {
       return;

app/assets/javascripts/discourse/tests/acceptance/topic-test.js

@@ -3,6 +3,7 @@ import {
   chromeTest,
   count,
   exists,
+  publishToMessageBus,
   query,
   queryAll,
   selectText,
@@ -12,6 +13,7 @@ import {
   click,
   currentURL,
   fillIn,
+  settled,
   triggerKeyEvent,
   visit,
 } from "@ember/test-helpers";
@@ -651,3 +653,136 @@ acceptance("Navigating between topics", function (needs) {
     assert.ok(currentURL().includes("/280"));
   });
 });
+
+acceptance("Topic stats update automatically", function () {
+  test("Likes count updates automatically", async function (assert) {
+    await visit("/t/internationalization-localization/280");
+
+    const likesDisplay = query("#post_1 .topic-map .likes .number");
+    const oldLikes = likesDisplay.textContent;
+
+    const likesChangedFixture = {
+      id: 280,
+      type: "stats",
+      like_count: 999,
+    };
+
+    // simulate the topic like_count being changed
+    publishToMessageBus("/topic/280", likesChangedFixture);
+
+    await settled();
+    const newLikes = likesDisplay.textContent;
+
+    assert.notEqual(
+      oldLikes,
+      newLikes,
+      "it updates the like count on the topic stats"
+    );
+    assert.equal(
+      newLikes,
+      likesChangedFixture.like_count,
+      "it updates the like count with the expected value"
+    );
+  });
+
+  const postsChangedFixture = {
+    id: 280,
+    type: "stats",
+    posts_count: 999,
+    last_posted_at: "2022-06-20T21:01:45.844Z",
+    last_poster: {
+      id: 1,
+      username: "test",
+      name: "Mr. Tester",
+      avatar_template: "http://www.example.com/avatar/updated_avatar.png",
+    },
+  };
+
+  test("Replies count updates automatically", async function (assert) {
+    await visit("/t/internationalization-localization/280");
+
+    const repliesDisplay = query("#post_1 .topic-map .replies .number");
+    const oldReplies = repliesDisplay.textContent;
+
+    // simulate the topic posts_count being changed
+    publishToMessageBus("/topic/280", postsChangedFixture);
+
+    await settled();
+    const newLikes = repliesDisplay.textContent;
+
+    assert.notEqual(
+      oldReplies,
+      newLikes,
+      "it updates the replies count on the topic stats"
+    );
+    assert.equal(
+      newLikes,
+      postsChangedFixture.posts_count - 1, // replies = posts_count - 1
+      "it updates the replies count with the expected value"
+    );
+  });
+
+  test("Last replier avatar updates automatically", async function (assert) {
+    await visit("/t/internationalization-localization/280");
+
+    const avatarImg = query("#post_1 .topic-map .last-reply .avatar");
+    const oldAvatarTitle = avatarImg.title;
+    const oldAvatarSrc = avatarImg.src;
+
+    // simulate the topic posts_count being changed
+    publishToMessageBus("/topic/280", postsChangedFixture);
+
+    await settled();
+
+    const newAvatarTitle = avatarImg.title;
+    const newAvatarSrc = avatarImg.src;
+
+    assert.notEqual(
+      oldAvatarTitle,
+      newAvatarTitle,
+      "it updates the last poster avatar title on the topic stats"
+    );
+    assert.equal(
+      newAvatarTitle,
+      postsChangedFixture.last_poster.name,
+      "it updates the last poster avatar title with the expected value"
+    );
+    assert.notEqual(
+      oldAvatarSrc,
+      newAvatarSrc,
+      "it updates the last poster avatar src on the topic stats"
+    );
+    assert.equal(
+      newAvatarSrc,
+      postsChangedFixture.last_poster.avatar_template,
+      "it updates the last poster avatar src with the expected value"
+    );
+  });
+
+  test("Last replied at updates automatically", async function (assert) {
+    await visit("/t/internationalization-localization/280");
+
+    const lastRepliedAtDisplay = query(
+      "#post_1 .topic-map .last-reply .relative-date"
+    );
+    const oldTime = lastRepliedAtDisplay.dataset.time;
+
+    // simulate the topic posts_count being changed
+    publishToMessageBus("/topic/280", postsChangedFixture);
+
+    await settled();
+
+    const newTime = lastRepliedAtDisplay.dataset.time;
+
+    assert.notEqual(
+      oldTime,
+      newTime,
+      "it updates the last posted time on the topic stats"
+    );
+    assert.equal(
+      newTime,
+      new Date(postsChangedFixture.last_posted_at).getTime(),
+      "it updates the last posted time with the expected value"
+    );
+  });
+});

app/models/post.rb

@@ -198,6 +198,8 @@ class Post < ActiveRecord::Base
     # but message is safe to skip
     return unless topic
 
+    skip_topic_stats = opts.delete(:skip_topic_stats)
+
     message = {
       id: id,
       post_number: post_number,
@@ -209,19 +211,14 @@ class Post < ActiveRecord::Base
     }.merge(opts)
 
     publish_message!("/topic/#{topic_id}", message)
+    Topic.publish_stats_to_clients!(topic.id, type) unless skip_topic_stats
   end
 
   def publish_message!(channel, message, opts = {})
     return unless topic
 
     if Topic.visible_post_types.include?(post_type)
-      if topic.private_message?
-        opts[:user_ids] = User.human_users.where("admin OR moderator").pluck(:id)
-        opts[:user_ids] |= topic.allowed_users.pluck(:id)
-        opts[:user_ids] |= topic.allowed_group_users.pluck(:id)
-      else
-        opts[:group_ids] = topic.secure_group_ids
-      end
+      opts.merge!(topic.secure_audience_publish_messages)
     else
       opts[:user_ids] = User.human_users
         .where("admin OR moderator OR id = ?", user_id)

app/models/topic.rb

@@ -783,7 +783,7 @@ class Topic < ActiveRecord::Base
     SQL
   end
 
-  # If a post is deleted we have to update our highest post counters
+  # If a post is deleted we have to update our highest post counters and last post information
   def self.reset_highest(topic_id)
     archetype = Topic.where(id: topic_id).pluck_first(:archetype)
 
@@ -818,7 +818,16 @@ class Topic < ActiveRecord::Base
                 deleted_at IS NULL AND
                 post_type <> 4
                 #{post_type}
-        )
+        ),
+        last_post_user_id = COALESCE((
+          SELECT user_id FROM posts
+          WHERE topic_id = :topic_id AND
+                deleted_at IS NULL AND
+                post_type <> 4
+                #{post_type}
+          ORDER BY created_at desc
+          LIMIT 1
+        ), last_post_user_id)
       WHERE id = :topic_id
       RETURNING highest_post_number
     SQL
@@ -1805,6 +1814,49 @@ class Topic < ActiveRecord::Base
     self.allowed_groups.where(smtp_enabled: true).first
   end
 
+  def secure_audience_publish_messages
+    target_audience = {}
+
+    if private_message?
+      target_audience[:user_ids] = User.human_users.where("admin OR moderator").pluck(:id)
+      target_audience[:user_ids] |= allowed_users.pluck(:id)
+      target_audience[:user_ids] |= allowed_group_users.pluck(:id)
+    else
+      target_audience[:group_ids] = secure_group_ids
+    end
+
+    target_audience
+  end
+
+  def self.publish_stats_to_clients!(topic_id, type, opts = {})
+    topic = Topic.find_by(id: topic_id)
+    return unless topic.present?
+
+    case type
+    when :liked, :unliked
+      stats = { like_count: topic.like_count }
+    when :created, :destroyed, :deleted, :recovered
+      stats = { posts_count: topic.posts_count,
+                last_posted_at: topic.last_posted_at.as_json,
+                last_poster: BasicUserSerializer.new(topic.last_poster, root: false).as_json }
+    else
+      stats = nil
+    end
+
+    if stats
+      secure_audience = topic.secure_audience_publish_messages
+
+      if secure_audience[:user_ids] != [] && secure_audience[:group_ids] != []
+        message = stats.merge({
+                                id: topic_id,
+                                updated_at: Time.now,
+                                type: :stats,
+                              })
+        MessageBus.publish("/topic/#{topic_id}", message, opts.merge(secure_audience))
+      end
+    end
+  end
+
   private
 
   def invite_to_private_message(invited_by, target_user, guardian)

lib/post_creator.rb

@@ -633,7 +633,7 @@ class PostCreator
 
   def publish
     return if @opts[:import_mode] || @post.post_number == 1
-    @post.publish_change_to_clients! :created
+    @post.publish_change_to_clients! :created, { skip_topic_stats: @post.post_number == 1 }
   end
 
   def extract_links

lib/post_destroyer.rb

@@ -98,6 +98,7 @@ class PostDestroyer
     topic.update_column(:user_id, Discourse::SYSTEM_USER_ID) if !topic.user_id
     topic.recover!(@user) if @post.is_first_post?
     topic.update_statistics
+    Topic.publish_stats_to_clients!(topic.id, :recovered)
 
     UserActionManager.post_created(@post)
     DiscourseEvent.trigger(:post_recovered, @post, @opts, @user)
@@ -135,7 +136,8 @@ class PostDestroyer
       end
     end
 
-    @post.publish_change_to_clients! :recovered
+    # skip also publishing topic stats because they weren't updated yet
+    @post.publish_change_to_clients! :recovered, { skip_topic_stats: true }
     TopicTrackingState.publish_recover(@post.topic) if @post.topic && @post.is_first_post?
   end
 

spec/lib/post_action_creator_spec.rb

@@ -67,12 +67,28 @@ describe PostActionCreator do
         PostActionCreator.new(user, post, like_type_id).perform
       end
 
-      message = messages.last.data
+      message = messages.find { |msg| msg.data[:type] === :liked }.data
+      expect(message).to be_present
       expect(message[:type]).to eq(:liked)
       expect(message[:likes_count]).to eq(1)
       expect(message[:user_id]).to eq(user.id)
     end
 
+    it 'notifies updated topic stats to subscribers' do
+      topic = Fabricate(:topic)
+      post = Fabricate(:post, topic: topic)
+
+      expect(post.reload.like_count).to eq(0)
+
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        PostActionCreator.new(user, post, like_type_id).perform
+      end
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_present
+      expect(stats_message.data[:like_count]).to eq(1)
+    end
+
     it 'does not create an invalid post action' do
       result = PostActionCreator.new(user, nil, like_type_id).perform
       expect(result.failed?).to eq(true)

spec/lib/post_action_destroyer_spec.rb

@@ -25,11 +25,28 @@ describe PostActionDestroyer do
             PostActionDestroyer.destroy(user, post, :like)
           end
 
-          message = messages.last.data
+          message = messages.find { |msg| msg.data[:type] === :unliked }.data
+          expect(message).to be_present
           expect(message[:type]).to eq(:unliked)
           expect(message[:likes_count]).to eq(0)
           expect(message[:user_id]).to eq(user.id)
         end
+
+        it 'notifies updated topic stats to subscribers' do
+          topic = Fabricate(:topic)
+          post = Fabricate(:post, topic: topic)
+          PostActionCreator.new(user, post, PostActionType.types[:like]).perform
+
+          expect(post.reload.like_count).to eq(1)
+
+          messages = MessageBus.track_publish("/topic/#{topic.id}") do
+            PostActionDestroyer.destroy(user, post, :like)
+          end
+
+          stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+          expect(stats_message).to be_present
+          expect(stats_message.data[:like_count]).to eq(0)
+        end
       end
 
       context 'post action doesn’t exist' do

spec/lib/post_creator_spec.rb

@@ -162,7 +162,7 @@ describe PostCreator do
 
         channels = messages.map { |m| m.channel }.sort
 
-        # 2 for topic, one to notify of new topic another for tracking state
+        # 3 for topic, one to notify of new topic, one for topic stats and another for tracking state
         expect(channels).to eq(
           [
             "/new",
@@ -174,6 +174,7 @@ describe PostCreator do
             "/latest",
             "/topic/#{created_post.topic_id}",
             "/topic/#{created_post.topic_id}",
+            "/topic/#{created_post.topic_id}",
             "/user-drafts/#{admin.id}",
             "/user-drafts/#{admin.id}",
             "/user-drafts/#{admin.id}",
@@ -208,6 +209,9 @@ describe PostCreator do
         draft_count = messages.find { |m| m.channel == "/user-drafts/#{p.user_id}" }
         expect(draft_count).not_to eq(nil)
 
+        topics_stats = messages.find { |m| m.channel == "/topic/#{p.topic.id}" && m.data[:type] == :stats }
+        expect(topics_stats).to eq(nil)
+
         expect(messages.filter { |m| m.channel != "/distributed_hash" }.length).to eq(7)
       end
 
@@ -851,6 +855,26 @@ describe PostCreator do
         expect(topic.word_count).to eq(6)
       end
 
+      it "publishes updates to topic stats" do
+        reply_timestamp = 1.day.from_now.round
+
+        # tests if messages of type :stats are published and the relevant data is fetched from the topic
+        messages = MessageBus.track_publish("/topic/#{topic.id}") do
+          PostCreator.new(
+            evil_trout,
+            raw: 'other post in topic',
+            topic_id: topic.id,
+            created_at: reply_timestamp
+          ).create
+        end
+
+        stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+        expect(stats_message).to be_present
+        expect(stats_message.data[:posts_count]).to eq(2)
+        expect(stats_message.data[:last_posted_at]).to eq(reply_timestamp.as_json)
+        expect(stats_message.data[:last_poster]).to eq(BasicUserSerializer.new(evil_trout, root: false).as_json)
+      end
+
       it "updates topic stats even when topic fails validation" do
         topic.update_columns(title: 'below 15 chars')
 

spec/lib/post_destroyer_spec.rb

@@ -1103,4 +1103,67 @@ describe PostDestroyer do
       expect { regular_post.reload }.to raise_error(ActiveRecord::RecordNotFound)
     end
   end
+
+  describe "publishes messages to subscribers" do
+    # timestamps are rounded because postgres truncates the timestamp. that would cause the comparison if we compared
+    # these timestamps with the one read from the database
+    fab!(:first_post) { Fabricate(:post, created_at: 10.days.ago.round) }
+    fab!(:walter_white) { Fabricate(:walter_white) }
+    let!(:topic) { first_post.topic }
+    let!(:reply) { Fabricate(:post, topic: topic, created_at: 5.days.ago.round, user: coding_horror) }
+    let!(:expendable_reply) { Fabricate(:post, topic: topic, created_at: 2.days.ago.round, user: walter_white) }
+
+    it 'when a post is destroyed publishes updated topic stats' do
+      expect(topic.reload.posts_count).to eq(3)
+
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        PostDestroyer.new(moderator, expendable_reply, force_destroy: true).destroy
+      end
+
+      expect { expendable_reply.reload }.to raise_error(ActiveRecord::RecordNotFound)
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_present
+      expect(stats_message.data[:posts_count]).to eq(2)
+      expect(stats_message.data[:last_posted_at]).to eq(reply.created_at.as_json)
+      expect(stats_message.data[:last_poster]).to eq(BasicUserSerializer.new(reply.user, root: false).as_json)
+    end
+
+    it 'when a post is deleted publishes updated topic stats' do
+      expect(topic.reload.posts_count).to eq(3)
+
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        PostDestroyer.new(moderator, expendable_reply).destroy
+      end
+
+      expect(expendable_reply.reload.deleted_at).not_to eq(nil)
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_present
+      expect(stats_message.data[:posts_count]).to eq(2)
+      expect(stats_message.data[:last_posted_at]).to eq(reply.created_at.as_json)
+      expect(stats_message.data[:last_poster]).to eq(BasicUserSerializer.new(reply.user, root: false).as_json)
+    end
+
+    it 'when a post is recovered publishes update topic stats' do
+      expect(topic.reload.posts_count).to eq(3)
+
+      PostDestroyer.new(moderator, expendable_reply).destroy
+      expect(topic.reload.posts_count).to eq(2)
+
+      expendable_reply.reload
+
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        PostDestroyer.new(admin, expendable_reply).recover
+      end
+
+      expect(topic.reload.posts_count).to eq(3)
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_present
+      expect(stats_message.data[:posts_count]).to eq(3)
+      expect(stats_message.data[:last_posted_at]).to eq(expendable_reply.created_at.as_json)
+      expect(stats_message.data[:last_poster]).to eq(BasicUserSerializer.new(expendable_reply.user, root: false).as_json)
+    end
+  end
 end

spec/models/post_spec.rb

@@ -1826,10 +1826,41 @@ describe Post do
         version: post.version
       }
 
-      MessageBus.expects(:publish).once.with("/topic/#{topic.id}", message, is_a(Hash)) do |_, _, options|
-        options[:user_ids].sort == [user1.id, user2.id, user3.id].sort
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        post.publish_change_to_clients!(:created)
       end
-      post.publish_change_to_clients!(:created)
+
+      created_message = messages.select { |msg| msg.data[:type] == :created }.first
+      expect(created_message).to be_present
+      expect(created_message.data).to eq(message)
+      expect(created_message.user_ids.sort).to eq([user1.id, user2.id, user3.id].sort)
+
+      stats_message = messages.select { |msg| msg.data[:type] == :created }.first
+      expect(stats_message).to be_present
+      expect(stats_message.user_ids.sort).to eq([user1.id, user2.id, user3.id].sort)
+    end
+
+    it 'also publishes topic stats' do
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        post.publish_change_to_clients!(:created)
+      end
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_present
+    end
+
+    it 'skips publishing topic stats when requested' do
+      messages = MessageBus.track_publish("/topic/#{topic.id}") do
+        post.publish_change_to_clients!(:anything, { skip_topic_stats: true })
+      end
+
+      stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+      expect(stats_message).to be_blank
+
+      # ensure that :skip_topic_stats did not get merged with the message
+      other_message = messages.select { |msg| msg.data[:type] == :anything }.first
+      expect(other_message).to be_present
+      expect(other_message.data.key?(:skip_topic_stats)).to be_falsey
     end
   end
 

spec/models/topic_spec.rb

@@ -3051,4 +3051,53 @@ describe Topic do
       expect(topic.reload.cannot_permanently_delete_reason(Fabricate(:admin))).to eq(nil)
     end
   end
+
+  describe "#publish_stats_to_clients!" do
+    fab!(:user1) { Fabricate(:user) }
+    fab!(:user2) { Fabricate(:user) }
+    fab!(:topic) { Fabricate(:topic, user: user1) }
+    fab!(:post1) { Fabricate(:post, topic: topic, user: user1) }
+    fab!(:post2) { Fabricate(:post, topic: topic, user: user2) }
+    fab!(:like1) { Fabricate(:like, post: post1, user: user2) }
+
+    it "it is triggered when a post publishes a message of type :liked or :unliked" do
+      [:liked, :unliked].each do |action|
+        messages = MessageBus.track_publish("/topic/#{topic.id}") do
+          post1.publish_change_to_clients!(action)
+        end
+
+        stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+        expect(stats_message).to be_present
+        expect(stats_message.data[:like_count]).to eq(topic.like_count)
+      end
+    end
+
+    it "it is triggered when a post publishes a message of type :created, :destroyed, :deleted, :recovered" do
+      freeze_time Date.today
+
+      [:created, :destroyed, :deleted, :recovered].each do |action|
+        messages = MessageBus.track_publish("/topic/#{topic.id}") do
+          post1.publish_change_to_clients!(action)
+        end
+
+        stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+        expect(stats_message).to be_present
+        expect(stats_message.data[:posts_count]).to eq(topic.posts_count)
+        expect(stats_message.data[:last_posted_at]).to eq(topic.last_posted_at.as_json)
+        expect(stats_message.data[:last_poster]).to eq(BasicUserSerializer.new(topic.last_poster, root: false).as_json)
+      end
+    end
+
+    it "it is not triggered when a post publishes an unhandled kind of message" do
+      [:unhandled, :unknown, :dont_care].each do |action|
+        messages = MessageBus.track_publish("/topic/#{topic.id}") do
+          post1.publish_change_to_clients!(action)
+        end
+
+        stats_message = messages.select { |msg| msg.data[:type] == :stats }.first
+        expect(stats_message).to be_blank
+      end
+    end
+  end
+
 end