FEATURE: the ability to permanently destroy the private message (#11115)

PostDestroyer should accept the option to permanently destroy post from the database. In addition, when the first post is destroyed it destroys the whole topic.

Currently, that feature is limited to private messages and creator of the post. It will be used by discourse-encrypt to explode encrypted private messages.

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

@@ -1424,6 +1424,12 @@ export default Controller.extend(bufferedProperty("model"), {
               .then(() => refresh({ id: data.id }));
             break;
           }
+          case "destroyed": {
+            postStream
+              .triggerDestroyedPost(data.id)
+              .then(() => refresh({ id: data.id }));
+            break;
+          }
           case "recovered": {
             postStream
               .triggerRecoveredPost(data.id)

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

@@ -737,6 +737,12 @@ export default RestModel.extend({
     return Promise.resolve();
   },
 
+  triggerDestroyedPost(postId) {
+    const existing = this._identityMap[postId];
+    this.removePosts([existing]);
+    return Promise.resolve();
+  },
+
   triggerChangedPost(postId, updatedAt, opts) {
     opts = opts || {};
 

app/assets/javascripts/discourse/app/models/topic-tracking-state.js

@@ -6,6 +6,7 @@ import PreloadStore from "discourse/lib/preload-store";
 import Category from "discourse/models/category";
 import User from "discourse/models/user";
 import { deepEqual } from "discourse-common/lib/object";
+import DiscourseURL from "discourse/lib/url";
 
 function isNew(topic) {
   return (
@@ -148,6 +149,17 @@ const TopicTrackingState = EmberObject.extend({
       }
       tracker.incrementMessageCount();
     });
+
+    this.messageBus.subscribe("/destroy", (msg) => {
+      tracker.incrementMessageCount();
+      const currentRoute = DiscourseURL.router.currentRoute.parent;
+      if (
+        currentRoute.name === "topic" &&
+        parseInt(currentRoute.params.id, 10) === msg.topic_id
+      ) {
+        DiscourseURL.redirectTo("/");
+      }
+    });
   },
 
   mutedTopics() {

app/models/topic_tracking_state.rb

@@ -171,6 +171,17 @@ class TopicTrackingState
     MessageBus.publish("/delete", message.as_json, group_ids: group_ids)
   end
 
+  def self.publish_destroy(topic)
+    group_ids = topic.category && topic.category.secure_group_ids
+
+    message = {
+      topic_id: topic.id,
+      message_type: "destroy"
+    }
+
+    MessageBus.publish("/destroy", message.as_json, group_ids: group_ids)
+  end
+
   def self.publish_read(topic_id, last_read_post_number, user_id, notification_level = nil)
     highest_post_number = DB.query_single("SELECT highest_post_number FROM topics WHERE id = ?", topic_id).first
 

lib/post_destroyer.rb

@@ -66,7 +66,7 @@ class PostDestroyer
 
     delete_removed_posts_after = @opts[:delete_removed_posts_after] || SiteSetting.delete_removed_posts_after
 
-    if delete_removed_posts_after < 1 || post_is_reviewable? || Guardian.new(@user).can_moderate_topic?(topic)
+    if delete_removed_posts_after < 1 || post_is_reviewable? || Guardian.new(@user).can_moderate_topic?(topic) || permanent?
       perform_delete
     elsif @user.id == @post.user_id
       mark_for_deletion(delete_removed_posts_after)
@@ -140,9 +140,10 @@ class PostDestroyer
 
   # When a post is properly deleted. Well, it's still soft deleted, but it will no longer
   # show up in the topic
+  # Permanent option allows to hard delete.
   def perform_delete
     Post.transaction do
-      @post.trash!(@user)
+      permanent? ? @post.destroy! : @post.trash!(@user)
       if @post.topic
         make_previous_post_the_last_one
         mark_topic_changed
@@ -162,7 +163,9 @@ class PostDestroyer
         end
       end
 
-      @post.topic.trash!(@user) if @post.topic && @post.is_first_post?
+      if @post.topic && @post.is_first_post?
+        permanent? ? @post.topic.destroy! : @post.topic.trash!(@user)
+      end
       update_associated_category_latest_topic
       update_user_counts
       TopicUser.update_post_action_cache(post_id: @post.id)
@@ -178,8 +181,12 @@ class PostDestroyer
 
     update_imap_sync(@post, true) if @post.topic&.deleted_at
     feature_users_in_the_topic if @post.topic
-    @post.publish_change_to_clients! :deleted if @post.topic
+    @post.publish_change_to_clients!(permanent? ? :destroyed : :deleted) if @post.topic
-    TopicTrackingState.publish_delete(@post.topic) if @post.topic && @post.post_number == 1
+    TopicTrackingState.send(permanent? ? :publish_destroy : :publish_delete, @post.topic) if @post.topic && @post.post_number == 1
+  end
+
+  def permanent?
+    @opts[:permanent] && @user == @post.user && @post.topic.private_message?
   end
 
   # When a user 'deletes' their own post. We just change the text.

lib/svg_sprite/svg_sprite.rb

@@ -174,6 +174,7 @@ module SvgSprite
     "star",
     "step-backward",
     "step-forward",
+    "stopwatch",
     "stream",
     "sync-alt",
     "sync",

spec/components/post_destroyer_spec.rb

@@ -961,4 +961,27 @@ describe PostDestroyer do
       expect(user.user_profile.reload.featured_topic).to eq(nil)
     end
   end
+
+  describe "permanent destroy" do
+    fab!(:private_message_topic) { Fabricate(:private_message_topic) }
+    fab!(:private_post) { Fabricate(:private_message_post, topic: private_message_topic) }
+    fab!(:reply) { Fabricate(:private_message_post, topic: private_message_topic) }
+    it "destroys the post and topic if deleting first post" do
+      PostDestroyer.new(reply.user, reply, permanent: true).destroy
+      expect { reply.reload }.to raise_error(ActiveRecord::RecordNotFound)
+      expect(private_message_topic.reload.persisted?).to be true
+
+      PostDestroyer.new(private_post.user, private_post, permanent: true).destroy
+      expect { private_post.reload }.to raise_error(ActiveRecord::RecordNotFound)
+      expect { private_message_topic.reload }.to raise_error(ActiveRecord::RecordNotFound)
+    end
+
+    it 'soft delete if not creator of post or not private message' do
+      PostDestroyer.new(moderator, reply, permanent: true).destroy
+      expect(reply.deleted_at).not_to eq(nil)
+
+      PostDestroyer.new(post.user, post, permanent: true).destroy
+      expect(post.user_deleted).to be true
+    end
+  end
 end