Convert clusters to use a top-level controller

In preparation so that we can create both cluster attached to project
and cluster attached to group.

- Move ClustersController to top level

- Move Clusters::ApplicationsController to top-level too

- Creates a Clusters::BaseController to share common functions

- Do not rely on @Project ivar. Anything could set the ivar.

- Fix Vue page components due to new data-page value

Because of the controller change we have gone from
`projects:clusters:new` to `clusters:new`, so we need to update the file
location of the page components. There is somewhere a function that will
convert data-page to a file location.

On that note, projects/clusters/gcp/new/, translate to
Projects::Clusters::Gcp#new doesn't exist so replace that with
clusters/create_gcp/ and clusters/create_user/

app/assets/javascripts/pages/projects/clusters/gcp/new/index.js → app/assets/javascripts/pages/clusters/create_gcp/index.js

+import initDismissableCallout from '~/dismissable_callout';
 import initGkeDropdowns from '~/projects/gke_cluster_dropdowns';
 document.addEventListener('DOMContentLoaded', () => {
+  initDismissableCallout('.gcp-signup-offer');
   initGkeDropdowns();
 });

app/assets/javascripts/pages/clusters/create_user/index.js

+import initDismissableCallout from '~/dismissable_callout';
+import initGkeDropdowns from '~/projects/gke_cluster_dropdowns';
+
+document.addEventListener('DOMContentLoaded', () => {
+  initDismissableCallout('.gcp-signup-offer');
+  initGkeDropdowns();
+});

app/assets/javascripts/pages/clusters/new/index.js

+import initDismissableCallout from '~/dismissable_callout';
+import initGkeDropdowns from '~/projects/gke_cluster_dropdowns';
+
+document.addEventListener('DOMContentLoaded', () => {
+  initDismissableCallout('.gcp-signup-offer');
+  initGkeDropdowns();
+});

app/assets/javascripts/pages/projects/index.js

-import initDismissableCallout from '~/dismissable_callout';
-import initGkeDropdowns from '~/projects/gke_cluster_dropdowns';
 import Project from './project';
 import ShortcutsNavigation from '../../behaviors/shortcuts/shortcuts_navigation';
 document.addEventListener('DOMContentLoaded', () => {
-  const { page } = document.body.dataset;
-  const newClusterViews = [
-    'projects:clusters:new',
-    'projects:clusters:create_gcp',
-    'projects:clusters:create_user',
-  ];
-
-  if (newClusterViews.indexOf(page) > -1) {
-    initDismissableCallout('.gcp-signup-offer');
-    initGkeDropdowns();
-  }
-
   new Project(); // eslint-disable-line no-new
   new ShortcutsNavigation(); // eslint-disable-line no-new
 });

app/controllers/projects/clusters/applications_controller.rb → app/controllers/clusters/applications_controller.rb

 # frozen_string_literal: true
-class Projects::Clusters::ApplicationsController < Projects::ApplicationController
+class Clusters::ApplicationsController < Clusters::BaseController
   before_action :cluster
-  before_action :authorize_read_cluster!
   before_action :authorize_create_cluster!, only: [:create]
   def create

app/controllers/clusters/base_controller.rb

+# frozen_string_literal: true
+
+class Clusters::BaseController < ApplicationController
+  include RoutableActions
+
+  skip_before_action :authenticate_user!
+  before_action :require_project_id
+  before_action :project, if: :project_type?
+  before_action :repository, if: :project_type?
+  before_action :authorize_read_cluster!
+
+  private
+
+  # We can extend to `#group_type?` in the future
+  def require_project_id
+    not_found unless project_type?
+  end
+
+  def project
+    @project ||= find_routable!(Project, File.join(params[:namespace_id], params[:project_id]))
+  end
+
+  def repository
+    @repository ||= project.repository
+  end
+
+  def authorize_read_cluster!
+    access_denied! unless can?(current_user, :read_cluster, clusterable)
+  end
+
+  def authorize_create_cluster!
+    access_denied! unless can?(current_user, :create_cluster, clusterable)
+  end
+
+  def clusterable
+    project if project_type?
+  end
+
+  def project_type?
+    params[:project_id].present?
+  end
+end

app/controllers/projects/clusters_controller.rb → app/controllers/clusters_controller.rb

 # frozen_string_literal: true
-class Projects::ClustersController < Projects::ApplicationController
+class ClustersController < Clusters::BaseController
   before_action :cluster, except: [:index, :new, :create_gcp, :create_user]
-  before_action :authorize_read_cluster!
   before_action :generate_gcp_authorize_url, only: [:new]
   before_action :validate_gcp_token, only: [:new]
   before_action :gcp_cluster, only: [:new]
@@ -11,6 +10,9 @@ class Projects::ClustersController < Projects::ApplicationController
   before_action :authorize_update_cluster!, only: [:update]
   before_action :authorize_admin_cluster!, only: [:destroy]
   before_action :update_applications_status, only: [:status]
+
+  layout :determine_layout
+
   helper_method :token_in_session
   STATUS_POLLING_INTERVAL = 10_000
@@ -29,7 +31,7 @@ class Projects::ClustersController < Projects::ApplicationController
         Gitlab::PollingInterval.set_header(response, interval: STATUS_POLLING_INTERVAL)
         render json: ClusterSerializer
-          .new(project: @project, current_user: @current_user)
+          .new(project: project, current_user: @current_user)
           .represent_status(@cluster)
       end
     end
@@ -105,6 +107,12 @@ class Projects::ClustersController < Projects::ApplicationController
   private
+  def determine_layout
+    if project_type?
+      'project'
+    end
+  end
+
   def cluster
     @cluster ||= project.clusters.find(params[:id])
                                  .present(current_user: current_user)
@@ -169,7 +177,7 @@ class Projects::ClustersController < Projects::ApplicationController
   end
   def generate_gcp_authorize_url
-    state = generate_session_key_redirect(new_project_cluster_path(@project).to_s)
+    state = generate_session_key_redirect(new_project_cluster_path(project).to_s)
     @authorize_url = GoogleApi::CloudPlatform::Client.new(
       nil, callback_google_api_auth_url,

app/helpers/clusters_helper.rb

@@ -10,7 +10,7 @@ module ClustersHelper
     return unless show_gcp_signup_offer?
     content_tag :section, class: 'no-animate expanded' do
-      render 'projects/clusters/gcp_signup_offer_banner'
+      render 'clusters/gcp_signup_offer_banner'
     end
   end
 end