Move to project dropdown with infinite scroll for better performance

7 files changed, 296 insertions, 116 deletions

diff --git a/CHANGELOG b/CHANGELOG
index f5416434ab1..b9d7cdd9127 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -66,6 +66,7 @@ v 8.11.0 (unreleased)
   - Add commit stats in commit api. !5517 (dixpac)
   - Add CI configuration button on project page
   - Make error pages responsive (Takuya Noguchi)
+  - Move to project dropdown with infinite scroll for better performance
   - Fix skip_repo parameter being ignored when destroying a namespace
   - Change requests_profiles resource constraint to catch virtually any file
   - Bump gitlab_git to lazy load compare commits
diff --git a/app/assets/javascripts/issuable_form.js b/app/assets/javascripts/issuable_form.js
index 297d4f029f0..b7f92ae9883 100644
--- a/app/assets/javascripts/issuable_form.js
+++ b/app/assets/javascripts/issuable_form.js
@@ -102,20 +102,34 @@
     };
 
     IssuableForm.prototype.initMoveDropdown = function() {
-      var $moveDropdown;
+      var $moveDropdown, pageSize;
       $moveDropdown = $('.js-move-dropdown');
       if ($moveDropdown.length) {
+        pageSize = $moveDropdown.data('page-size');
         return $('.js-move-dropdown').select2({
           ajax: {
             url: $moveDropdown.data('projects-url'),
-            results: function(data) {
+            quietMillis: 125,
+            data: function(term, page, context) {
               return {
-                results: data
+                search: term,
+                offset_id: context
               };
             },
-            data: function(query) {
+            results: function(data) {
+              var context,
+                more;
+
+              if (data.length >= pageSize)
+                more = true;
+
+              if (data[data.length - 1])
+                context = data[data.length - 1].id;
+
               return {
-                search: query
+                results: data,
+                more: more,
+                context: context
               };
             }
           },
diff --git a/app/assets/stylesheets/framework/selects.scss b/app/assets/stylesheets/framework/selects.scss
index 21d87cc9d34..b2e22b60440 100644
--- a/app/assets/stylesheets/framework/selects.scss
+++ b/app/assets/stylesheets/framework/selects.scss
@@ -45,7 +45,8 @@
   min-width: 175px;
 }
 
-.select2-results .select2-result-label {
+.select2-results .select2-result-label,
+.select2-more-results {
   padding: 10px 15px;
 }
 
diff --git a/app/controllers/autocomplete_controller.rb b/app/controllers/autocomplete_controller.rb
index d828d163c28..350106a0b29 100644
--- a/app/controllers/autocomplete_controller.rb
+++ b/app/controllers/autocomplete_controller.rb
@@ -34,19 +34,15 @@ class AutocompleteController < ApplicationController
 
   def projects
     project = Project.find_by_id(params[:project_id])
+    projects = projects_finder.execute(project, search: params[:search], offset_id: params[:offset_id])
 
-    projects = current_user.authorized_projects
-    projects = projects.search(params[:search]) if params[:search].present?
-    projects = projects.select do |project|
-      current_user.can?(:admin_issue, project)
-    end
+    ActiveRecord::Associations::Preloader.new.preload(projects, { namespace: :owner })
 
     no_project = {
       id: 0,
       name_with_namespace: 'No project',
     }
-    projects.unshift(no_project)
-    projects.delete(project)
+    projects.unshift(no_project) unless params[:offset_id].present?
 
     render json: projects.to_json(only: [:id, :name_with_namespace], methods: :name_with_namespace)
   end
@@ -71,4 +67,8 @@ class AutocompleteController < ApplicationController
         User.none
       end
   end
+
+  def projects_finder
+    MoveToProjectFinder.new(current_user)
+  end
 end
diff --git a/app/finders/move_to_project_finder.rb b/app/finders/move_to_project_finder.rb
new file mode 100644
index 00000000000..54e7e55aa05
--- /dev/null
+++ b/app/finders/move_to_project_finder.rb
@@ -0,0 +1,30 @@
+class MoveToProjectFinder
+  PAGE_SIZE = 50
+
+  def initialize(user)
+    @user = user
+  end
+
+  def execute(from_project, search: nil, offset_id: nil)
+    projects = @user.authorized_projects
+    projects = projects.search(search) if search.present?
+    projects = skip_projects_before(projects, offset_id.to_i) if offset_id.present?
+    projects = take_projects(projects)
+    projects.delete(from_project)
+    projects
+  end
+
+  private
+
+  def skip_projects_before(projects, offset_project_id)
+    index = projects.index { |project| project.id == offset_project_id }
+
+    index ? projects.drop(index + 1) : projects
+  end
+
+  def take_projects(projects)
+    projects.lazy.select do |project|
+      @user.can?(:admin_issue, project)
+    end.take(PAGE_SIZE).to_a
+  end
+end
diff --git a/app/views/shared/issuable/_form.html.haml b/app/views/shared/issuable/_form.html.haml
index c30bdb0ae91..1b12b580a16 100644
--- a/app/views/shared/issuable/_form.html.haml
+++ b/app/views/shared/issuable/_form.html.haml
@@ -98,7 +98,7 @@
     = label_tag :move_to_project_id, 'Move', class: 'control-label'
     .col-sm-10
       .issuable-form-select-holder
-        = hidden_field_tag :move_to_project_id, nil, class: 'js-move-dropdown', data: { placeholder: 'Select project', projects_url: autocomplete_projects_path(project_id: @project.id) }
+        = hidden_field_tag :move_to_project_id, nil, class: 'js-move-dropdown', data: { placeholder: 'Select project', projects_url: autocomplete_projects_path(project_id: @project.id), page_size: MoveToProjectFinder::PAGE_SIZE }
       &nbsp;
       %span{ data: { toggle: 'tooltip', placement: 'auto top' }, style: 'cursor: default',
       title: 'Moving an issue will copy the discussion to a different project and close it here. All participants will be notified of the new location.' }
diff --git a/spec/controllers/autocomplete_controller_spec.rb b/spec/controllers/autocomplete_controller_spec.rb
index ed0b7f9e240..a121cb2fc97 100644
--- a/spec/controllers/autocomplete_controller_spec.rb
+++ b/spec/controllers/autocomplete_controller_spec.rb
@@ -2,178 +2,312 @@ require 'spec_helper'
 
 describe AutocompleteController do
   let!(:project) { create(:project) }
-  let!(:user)    { create(:user) }
-  let!(:user2)   { create(:user) }
-  let!(:non_member)   { create(:user) }
+  let!(:user) { create(:user) }
 
-  context 'project members' do
-    before do
-      sign_in(user)
-      project.team << [user, :master]
-    end
+  context 'users and members' do
+    let!(:user2) { create(:user) }
+    let!(:non_member) { create(:user) }
 
-    describe 'GET #users with project ID' do
+    context 'project members' do
       before do
-        get(:users, project_id: project.id)
+        sign_in(user)
+        project.team << [user, :master]
       end
 
-      let(:body) { JSON.parse(response.body) }
+      describe 'GET #users with project ID' do
+        before do
+          get(:users, project_id: project.id)
+        end
 
-      it { expect(body).to be_kind_of(Array) }
-      it { expect(body.size).to eq 1 }
-      it { expect(body.map { |u| u["username"] }).to include(user.username) }
+        let(:body) { JSON.parse(response.body) }
+
+        it { expect(body).to be_kind_of(Array) }
+        it { expect(body.size).to eq 1 }
+        it { expect(body.map { |u| u["username"] }).to include(user.username) }
+      end
+
+      describe 'GET #users with unknown project' do
+        before do
+          get(:users, project_id: 'unknown')
+        end
+
+        it { expect(response).to have_http_status(404) }
+      end
     end
 
-    describe 'GET #users with unknown project' do
+    context 'group members' do
+      let(:group) { create(:group) }
+
       before do
-        get(:users, project_id: 'unknown')
+        sign_in(user)
+        group.add_owner(user)
       end
 
-      it { expect(response).to have_http_status(404) }
-    end
-  end
+      let(:body) { JSON.parse(response.body) }
 
-  context 'group members' do
-    let(:group) { create(:group) }
+      describe 'GET #users with group ID' do
+        before do
+          get(:users, group_id: group.id)
+        end
 
-    before do
-      sign_in(user)
-      group.add_owner(user)
+        it { expect(body).to be_kind_of(Array) }
+        it { expect(body.size).to eq 1 }
+        it { expect(body.first["username"]).to eq user.username }
+      end
+
+      describe 'GET #users with unknown group ID' do
+        before do
+          get(:users, group_id: 'unknown')
+        end
+
+        it { expect(response).to have_http_status(404) }
+      end
     end
 
-    let(:body) { JSON.parse(response.body) }
+    context 'non-member login for public project' do
+      let!(:project) { create(:project, :public) }
 
-    describe 'GET #users with group ID' do
       before do
-        get(:users, group_id: group.id)
+        sign_in(non_member)
+        project.team << [user, :master]
       end
 
-      it { expect(body).to be_kind_of(Array) }
-      it { expect(body.size).to eq 1 }
-      it { expect(body.first["username"]).to eq user.username }
+      let(:body) { JSON.parse(response.body) }
+
+      describe 'GET #users with project ID' do
+        before do
+          get(:users, project_id: project.id, current_user: true)
+        end
+
+        it { expect(body).to be_kind_of(Array) }
+        it { expect(body.size).to eq 2 }
+        it { expect(body.map { |u| u['username'] }).to match_array([user.username, non_member.username]) }
+      end
     end
 
-    describe 'GET #users with unknown group ID' do
+    context 'all users' do
       before do
-        get(:users, group_id: 'unknown')
+        sign_in(user)
+        get(:users)
       end
 
-      it { expect(response).to have_http_status(404) }
+      let(:body) { JSON.parse(response.body) }
+
+      it { expect(body).to be_kind_of(Array) }
+      it { expect(body.size).to eq User.count }
     end
-  end
 
-  context 'non-member login for public project' do
-    let!(:project) { create(:project, :public) }
+    context 'unauthenticated user' do
+      let(:public_project) { create(:project, :public) }
+      let(:body) { JSON.parse(response.body) }
 
-    before do
-      sign_in(non_member)
-      project.team << [user, :master]
-    end
+      describe 'GET #users with public project' do
+        before do
+          public_project.team << [user, :guest]
+          get(:users, project_id: public_project.id)
+        end
+
+        it { expect(body).to be_kind_of(Array) }
+        it { expect(body.size).to eq 1 }
+      end
 
-    let(:body) { JSON.parse(response.body) }
+      describe 'GET #users with project' do
+        before do
+          get(:users, project_id: project.id)
+        end
 
-    describe 'GET #users with project ID' do
-      before do
-        get(:users, project_id: project.id, current_user: true)
+        it { expect(response).to have_http_status(404) }
       end
 
-      it { expect(body).to be_kind_of(Array) }
-      it { expect(body.size).to eq 2 }
-      it { expect(body.map { |u| u['username'] }).to match_array([user.username, non_member.username]) }
-    end
-  end
+      describe 'GET #users with unknown project' do
+        before do
+          get(:users, project_id: 'unknown')
+        end
 
-  context 'all users' do
-    before do
-      sign_in(user)
-      get(:users)
-    end
+        it { expect(response).to have_http_status(404) }
+      end
 
-    let(:body) { JSON.parse(response.body) }
+      describe 'GET #users with inaccessible group' do
+        before do
+          project.team << [user, :guest]
+          get(:users, group_id: user.namespace.id)
+        end
 
-    it { expect(body).to be_kind_of(Array) }
-    it { expect(body.size).to eq User.count }
-  end
+        it { expect(response).to have_http_status(404) }
+      end
+
+      describe 'GET #users with no project' do
+        before do
+          get(:users)
+        end
 
-  context 'unauthenticated user' do
-    let(:public_project) { create(:project, :public) }
-    let(:body) { JSON.parse(response.body) }
+        it { expect(body).to be_kind_of(Array) }
+        it { expect(body.size).to eq 0 }
+      end
+    end
 
-    describe 'GET #users with public project' do
+    context 'author of issuable included' do
       before do
-        public_project.team << [user, :guest]
-        get(:users, project_id: public_project.id)
+        sign_in(user)
       end
 
-      it { expect(body).to be_kind_of(Array) }
-      it { expect(body.size).to eq 1 }
+      let(:body) { JSON.parse(response.body) }
+
+      it 'includes the author' do
+        get(:users, author_id: non_member.id)
+
+        expect(body.first["username"]).to eq non_member.username
+      end
+
+      it 'rejects non existent user ids' do
+        get(:users, author_id: 99999)
+
+        expect(body.collect { |u| u['id'] }).not_to include(99999)
+      end
     end
 
-    describe 'GET #users with project' do
-      before do
-        get(:users, project_id: project.id)
+    context 'skip_users parameter included' do
+      before { sign_in(user) }
+
+      it 'skips the user IDs passed' do
+        get(:users, skip_users: [user, user2].map(&:id))
+
+        other_user_ids    = [non_member, project.owner, project.creator].map(&:id)
+        response_user_ids = JSON.parse(response.body).map { |user| user['id'] }
+
+        expect(response_user_ids).to contain_exactly(*other_user_ids)
       end
+    end
+  end
+
+  context 'projects' do
+    let(:authorized_project) { create(:project) }
+    let(:authorized_search_project) { create(:project, name: 'rugged') }
 
-      it { expect(response).to have_http_status(404) }
+    before do
+      sign_in(user)
+      project.team << [user, :master]
     end
 
-    describe 'GET #users with unknown project' do
+    context 'authorized projects' do
       before do
-        get(:users, project_id: 'unknown')
+        authorized_project.team << [user, :master]
       end
 
-      it { expect(response).to have_http_status(404) }
+      describe 'GET #projects with project ID' do
+        before do
+          get(:projects, project_id: project.id)
+        end
+
+        let(:body) { JSON.parse(response.body) }
+
+        it do
+          expect(body).to be_kind_of(Array)
+          expect(body.size).to eq 2
+
+          expect(body.first['id']).to eq 0
+          expect(body.first['name_with_namespace']).to eq 'No project'
+
+          expect(body.last['id']).to eq authorized_project.id
+          expect(body.last['name_with_namespace']).to eq authorized_project.name_with_namespace
+        end
+      end
     end
 
-    describe 'GET #users with inaccessible group' do
+    context 'authorized projects and search' do
       before do
-        project.team << [user, :guest]
-        get(:users, group_id: user.namespace.id)
+        authorized_project.team << [user, :master]
+        authorized_search_project.team << [user, :master]
       end
 
-      it { expect(response).to have_http_status(404) }
+      describe 'GET #projects with project ID and search' do
+        before do
+          get(:projects, project_id: project.id, search: 'rugged')
+        end
+
+        let(:body) { JSON.parse(response.body) }
+
+        it do
+          expect(body).to be_kind_of(Array)
+          expect(body.size).to eq 2
+
+          expect(body.last['id']).to eq authorized_search_project.id
+          expect(body.last['name_with_namespace']).to eq authorized_search_project.name_with_namespace
+        end
+      end
     end
 
-    describe 'GET #users with no project' do
+    context 'authorized projects apply limit' do
       before do
-        get(:users)
+        authorized_project2 = create(:project)
+        authorized_project3 = create(:project)
+
+        authorized_project.team << [user, :master]
+        authorized_project2.team << [user, :master]
+        authorized_project3.team << [user, :master]
+
+        stub_const 'MoveToProjectFinder::PAGE_SIZE', 2
       end
 
-      it { expect(body).to be_kind_of(Array) }
-      it { expect(body.size).to eq 0 }
-    end
-  end
+      describe 'GET #projects with project ID' do
+        before do
+          get(:projects, project_id: project.id)
+        end
 
-  context 'author of issuable included' do
-    before do
-      sign_in(user)
+        let(:body) { JSON.parse(response.body) }
+
+        it do
+          expect(body).to be_kind_of(Array)
+          expect(body.size).to eq 3 # Of a total of 4
+        end
+      end
     end
 
-    let(:body) { JSON.parse(response.body) }
+    context 'authorized projects with offset' do
+      before do
+        authorized_project2 = create(:project)
+        authorized_project3 = create(:project)
 
-    it 'includes the author' do
-      get(:users, author_id: non_member.id)
+        authorized_project.team << [user, :master]
+        authorized_project2.team << [user, :master]
+        authorized_project3.team << [user, :master]
+      end
 
-      expect(body.first["username"]).to eq non_member.username
-    end
+      describe 'GET #projects with project ID and offset_id' do
+        before do
+          get(:projects, project_id: project.id, offset_id: authorized_project.id)
+        end
 
-    it 'rejects non existent user ids' do
-      get(:users, author_id: 99999)
+        let(:body) { JSON.parse(response.body) }
 
-      expect(body.collect { |u| u['id'] }).not_to include(99999)
+        it do
+          expect(body.detect { |item| item['id'] == 0 }).to be_nil # 'No project' is not there
+          expect(body.detect { |item| item['id'] == authorized_project.id }).to be_nil # Offset project is not there either
+        end
+      end
     end
-  end
 
-  context 'skip_users parameter included' do
-    before { sign_in(user) }
+    context 'authorized projects without admin_issue ability' do
+      before(:each) do
+        authorized_project.team << [user, :guest]
+
+        expect(user.can?(:admin_issue, authorized_project)).to eq(false)
+      end
+
+      describe 'GET #projects with project ID' do
+        before do
+          get(:projects, project_id: project.id)
+        end
 
-    it 'skips the user IDs passed' do
-      get(:users, skip_users: [user, user2].map(&:id))
+        let(:body) { JSON.parse(response.body) }
 
-      other_user_ids = [non_member, project.owner, project.creator].map(&:id)
-      response_user_ids = JSON.parse(response.body).map { |user| user['id'] }
+        it do
+          expect(body).to be_kind_of(Array)
+          expect(body.size).to eq 1 # 'No project'
 
-      expect(response_user_ids).to contain_exactly(*other_user_ids)
+          expect(body.first['id']).to eq 0
+        end
+      end
     end
   end
 end