FEATURE: revert post to a specific revision

app/assets/javascripts/discourse/controllers/history.js.es6

@@ -29,6 +29,25 @@ export default Ember.Controller.extend(ModalFunctionality, {
     Discourse.Post.showRevision(postId, postVersion).then(() => this.refresh(postId, postVersion));
   },
 
+  revert(post, postVersion) {
+    post.revertToRevision(postVersion).then((result) => {
+      this.refresh(post.get('id'), postVersion);
+      if (result.topic) {
+        post.set('topic.slug', result.topic.slug);
+        post.set('topic.title', result.topic.title);
+        post.set('topic.fancy_title', result.topic.fancy_title);
+      }
+      if (result.category_id) {
+        post.set('topic.category', Discourse.Category.findById(result.category_id));
+      }
+      this.send("closeModal");
+    }).catch(function(e) {
+      if (e.jqXHR.responseJSON && e.jqXHR.responseJSON.errors && e.jqXHR.responseJSON.errors[0]) {
+        bootbox.alert(e.jqXHR.responseJSON.errors[0]);
+      }
+    });
+  },
+
   @computed('model.created_at')
   createdAtDate(createdAt) {
     return moment(createdAt).format("LLLL");
@@ -69,6 +88,11 @@ export default Ember.Controller.extend(ModalFunctionality, {
     return !prevHidden && this.currentUser && this.currentUser.get('staff');
   },
 
+  @computed()
+  displayRevert() {
+    return this.currentUser && this.currentUser.get('staff');
+  },
+
   isEitherRevisionHidden: Ember.computed.or("model.previous_hidden", "model.current_hidden"),
 
   @computed('model.previous_hidden', 'model.current_hidden', 'displayingInline')
@@ -142,6 +166,8 @@ export default Ember.Controller.extend(ModalFunctionality, {
     hideVersion() { this.hide(this.get("model.post_id"), this.get("model.current_revision")); },
     showVersion() { this.show(this.get("model.post_id"), this.get("model.current_revision")); },
 
+    revertToVersion() { this.revert(this.get("post"), this.get("model.current_revision")); },
+
     displayInline()             { this.set("viewMode", "inline"); },
     displaySideBySide()         { this.set("viewMode", "side_by_side"); },
     displaySideBySideMarkdown() { this.set("viewMode", "side_by_side_markdown"); }

app/assets/javascripts/discourse/models/post.js.es6

@@ -271,6 +271,10 @@ const Post = RestModel.extend({
       json = Post.munge(json);
       this.set('actions_summary', json.actions_summary);
     }
+  },
+
+  revertToRevision(version) {
+    return Discourse.ajax(`/posts/${this.get('id')}/revisions/${version}/revert`, { type: 'PUT' });
   }
 
 });

app/assets/javascripts/discourse/routes/topic.js.es6

@@ -73,6 +73,7 @@ const TopicRoute = Discourse.Route.extend({
     showHistory(model) {
       showModal('history', { model });
       this.controllerFor('history').refresh(model.get("id"), "latest");
+      this.controllerFor('history').set('post', model);
       this.controllerFor('modal').set('modalClass', 'history-modal');
     },
 

app/assets/javascripts/discourse/templates/modal/history.hbs

@@ -10,12 +10,6 @@
       </div>
       {{d-button action="loadNextVersion" icon="forward" title="post.revisions.controls.next" disabled=loadNextDisabled}}
       {{d-button action="loadLastVersion" icon="fast-forward" title="post.revisions.controls.last" disabled=loadLastDisabled}}
-      {{#if displayHide}}
-        {{d-button action="hideVersion" icon="trash-o" title="post.revisions.controls.hide" class="btn-danger" disabled=loading}}
-      {{/if}}
-      {{#if displayShow}}
-        {{d-button action="showVersion" icon="undo" title="post.revisions.controls.show" disabled=loading}}
-      {{/if}}
     </div>
     <div id="display-modes">
       {{d-button action="displayInline" label="post.revisions.displays.inline.button" title="post.revisions.displays.inline.title" class=inlineClass}}
@@ -85,5 +79,15 @@
     <div class="row">
       {{{bodyDiff}}}
     </div>
+
+    {{#if displayRevert}}
+      {{d-button action="revertToVersion" icon="undo" label="post.revisions.controls.revert" class="btn-danger" disabled=loading}}
+    {{/if}}
+    {{#if displayHide}}
+      {{d-button action="hideVersion" icon="eye-slash" label="post.revisions.controls.hide" class="btn-danger" disabled=loading}}
+    {{/if}}
+    {{#if displayShow}}
+      {{d-button action="showVersion" icon="eye" label="post.revisions.controls.show" disabled=loading}}
+    {{/if}}
   </div>
 </div>

app/controllers/posts_controller.rb

@@ -282,6 +282,55 @@ class PostsController < ApplicationController
     render nothing: true
   end
 
+  def revert
+    raise Discourse::NotFound unless guardian.is_staff?
+
+    post_id = params[:id] || params[:post_id]
+    revision = params[:revision].to_i
+    raise Discourse::InvalidParameters.new(:revision) if revision < 2
+
+    post_revision = PostRevision.find_by(post_id: post_id, number: revision)
+    raise Discourse::NotFound unless post_revision
+
+    post = find_post_from_params
+    raise Discourse::NotFound if post.blank?
+
+    post_revision.post = post
+    guardian.ensure_can_see!(post_revision)
+    guardian.ensure_can_edit!(post)
+    return render_json_error(I18n.t('revert_version_same')) if post_revision.modifications["raw"].blank? && post_revision.modifications["title"].blank? && post_revision.modifications["category_id"].blank?
+
+    topic = Topic.with_deleted.find(post.topic_id)
+
+    changes = {}
+    changes[:raw] = post_revision.modifications["raw"][0] if post_revision.modifications["raw"].present? && post_revision.modifications["raw"][0] != post.raw
+    if post.is_first_post?
+      changes[:title] = post_revision.modifications["title"][0] if post_revision.modifications["title"].present? && post_revision.modifications["title"][0] != topic.title
+      changes[:category_id] = post_revision.modifications["category_id"][0] if post_revision.modifications["category_id"].present? && post_revision.modifications["category_id"][0] != topic.category.id
+    end
+    return render_json_error(I18n.t('revert_version_same')) unless changes.length > 0
+    changes[:edit_reason] = "reverted to version ##{post_revision.number.to_i - 1}"
+
+    revisor = PostRevisor.new(post, topic)
+    revisor.revise!(current_user, changes)
+
+    return render_json_error(post) if post.errors.present?
+    return render_json_error(topic) if topic.errors.present?
+
+    post_serializer = PostSerializer.new(post, scope: guardian, root: false)
+    post_serializer.draft_sequence = DraftSequence.current(current_user, topic.draft_key)
+    link_counts = TopicLink.counts_for(guardian, topic, [post])
+    post_serializer.single_post_link_counts = link_counts[post.id] if link_counts.present?
+
+    result = { post: post_serializer.as_json }
+    if post.is_first_post?
+      result[:topic] = BasicTopicSerializer.new(topic, scope: guardian, root: false).as_json if post_revision.modifications["title"].present?
+      result[:category_id] = post_revision.modifications["category_id"][0] if post_revision.modifications["category_id"].present?
+    end
+
+    render_json_dump(result)
+  end
+
   def bookmark
     post = find_post_from_params
 

config/locales/client.en.yml

@@ -1639,6 +1639,7 @@ en:
           last: "Last revision"
           hide: "Hide revision"
           show: "Show revision"
+          revert: "Revert to this revision"
           comparing_previous_to_current_out_of_total: "<strong>{{previous}}</strong> <i class='fa fa-arrows-h'></i> <strong>{{current}}</strong> / {{total}}"
         displays:
           inline:

config/locales/server.en.yml

@@ -204,6 +204,7 @@ en:
     top: "Top topics"
     posts: "Latest posts"
   too_late_to_edit: "That post was created too long ago. It can no longer be edited or deleted."
+  revert_version_same: "The current version is same as the version you are trying to revert to."
 
   excerpt_image: "image"
 

config/routes.rb

@@ -386,6 +386,7 @@ Discourse::Application.routes.draw do
     get "revisions/:revision" => "posts#revisions", constraints: { revision: /\d+/ }
     put "revisions/:revision/hide" => "posts#hide_revision", constraints: { revision: /\d+/ }
     put "revisions/:revision/show" => "posts#show_revision", constraints: { revision: /\d+/ }
+    put "revisions/:revision/revert" => "posts#revert", constraints: { revision: /\d+/ }
     put "recover"
     collection do
       delete "destroy_many"

spec/controllers/posts_controller_spec.rb

@@ -830,6 +830,79 @@ describe PostsController do
 
   end
 
+  describe 'revert post to a specific revision' do
+    include_examples 'action requires login', :put, :revert, post_id: 123, revision: 2
+
+    let(:post) { Fabricate(:post, user: logged_in_as, raw: "Lorem ipsum dolor sit amet, cu nam libris tractatos, ancillae senserit ius ex") }
+    let(:post_revision) { Fabricate(:post_revision, post: post, modifications: {"raw" => ["this is original post body.", "this is edited post body."]}) }
+    let(:blank_post_revision) { Fabricate(:post_revision, post: post, modifications: {"edit_reason" => ["edit reason #1", "edit reason #2"]}) }
+    let(:same_post_revision) { Fabricate(:post_revision, post: post, modifications: {"raw" => ["Lorem ipsum dolor sit amet, cu nam libris tractatos, ancillae senserit ius ex", "this is edited post body."]}) }
+
+    let(:revert_params) do
+      {
+        post_id: post.id,
+        revision: post_revision.number
+      }
+    end
+    let(:moderator) { Fabricate(:moderator) }
+
+    describe 'when logged in as a regular user' do
+      let(:logged_in_as) { log_in }
+
+      it "does not work" do
+        xhr :put, :revert, revert_params
+        expect(response).to_not be_success
+      end
+    end
+
+    describe "when logged in as staff" do
+      let(:logged_in_as) { log_in(:moderator) }
+
+      it "throws an exception when revision is < 2" do
+        expect {
+          xhr :put, :revert, post_id: post.id, revision: 1
+        }.to raise_error(Discourse::InvalidParameters)
+      end
+
+      it "fails when post_revision record is not found" do
+        xhr :put, :revert, post_id: post.id, revision: post_revision.number + 1
+        expect(response).to_not be_success
+      end
+
+      it "fails when post record is not found" do
+        xhr :put, :revert, post_id: post.id + 1, revision: post_revision.number
+        expect(response).to_not be_success
+      end
+
+      it "fails when revision is blank" do
+        xhr :put, :revert, post_id: post.id, revision: blank_post_revision.number
+
+        expect(response.status).to eq(422)
+        expect(JSON.parse(response.body)['errors']).to include(I18n.t('revert_version_same'))
+      end
+
+      it "fails when revised version is same as current version" do
+        xhr :put, :revert, post_id: post.id, revision: same_post_revision.number
+
+        expect(response.status).to eq(422)
+        expect(JSON.parse(response.body)['errors']).to include(I18n.t('revert_version_same'))
+      end
+
+      it "works!" do
+        xhr :put, :revert, revert_params
+        expect(response).to be_success
+      end
+
+      it "supports reverting posts in deleted topics" do
+        first_post = post.topic.ordered_posts.first
+        PostDestroyer.new(moderator, first_post).destroy
+
+        xhr :put, :revert, revert_params
+        expect(response).to be_success
+      end
+    end
+  end
+
   describe 'expandable embedded posts' do
     let(:post) { Fabricate(:post) }