Confluence nav links to new landing page

The Confluence nav item now links to a landing page for the user.

https://gitlab.com/gitlab-org/gitlab/-/issues/220934

app/controllers/projects/confluences_controller.rb

+# frozen_string_literal: true
+
+class Projects::ConfluencesController < Projects::ApplicationController
+  before_action :ensure_confluence
+
+  def show
+  end
+
+  private
+
+  def ensure_confluence
+    render_404 unless project.has_confluence?
+  end
+end

app/views/layouts/nav/sidebar/_project.html.haml

@@ -294,7 +294,7 @@
       = render 'layouts/nav/sidebar/analytics_links', links: project_analytics_navbar_links(@project, current_user)
 
       - if project_nav_tab?(:confluence)
-        - confluence_url = @project.confluence_service.confluence_url
+        - confluence_url = project_wikis_confluence_path(@project)
         = nav_link do
           = link_to confluence_url, class: 'shortcuts-confluence' do
             .nav-icon-container

app/views/projects/confluences/show.html.haml

+- breadcrumb_title _('Confluence')
+- page_title _('Confluence')
+= render layout: 'shared/empty_states/wikis_layout', locals: { image_path: 'illustrations/wiki_login_empty.svg' } do
+  %h4
+    = s_('WikiEmpty|Confluence is enabled')
+  %p
+    - wiki_confluence_epic_link_url = 'https://gitlab.com/groups/gitlab-org/-/epics/3629'
+    - wiki_confluence_epic_link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: wiki_confluence_epic_link_url }
+    = s_("WikiEmpty|You've enabled the Confluence Workspace integration. Your wiki will be viewable directly within Confluence. We are hard at work integrating Confluence more seamlessly into GitLab. If you'd like to stay up to date, follow our %{wiki_confluence_epic_link_start}Confluence epic%{wiki_confluence_epic_link_end}.").html_safe % { wiki_confluence_epic_link_start: wiki_confluence_epic_link_start, wiki_confluence_epic_link_end: '</a>'.html_safe }
+  = link_to @project.confluence_service.confluence_url, target: '_blank', rel: 'noopener noreferrer', class: 'btn btn-success external-url', title: s_('WikiEmpty|Go to Confluence') do
+    = sprite_icon('external-link')
+    = s_('WikiEmpty|Go to Confluence')
+

config/routes/wiki.rb

@@ -5,6 +5,9 @@ scope(controller: :wikis) do
     get :new
     get '/', to: redirect { |params, request| "#{request.path}/home" }
     post '/', to: 'wikis#create'
+    scope '-' do
+      resource :confluence, only: :show
+    end
   end
 
   scope(path: 'wikis/*id', as: :wiki, format: false) do

locale/gitlab.pot

@@ -26420,12 +26420,18 @@ msgstr ""
 msgid "WikiEmpty|A wiki is where you can store all the details about your project. This can include why you've created it, its principles, how to use it, and so on."
 msgstr ""
 
+msgid "WikiEmpty|Confluence is enabled"
+msgstr ""
+
 msgid "WikiEmpty|Create your first page"
 msgstr ""
 
 msgid "WikiEmpty|Enable the Confluence Wiki integration"
 msgstr ""
 
+msgid "WikiEmpty|Go to Confluence"
+msgstr ""
+
 msgid "WikiEmpty|Suggest wiki improvement"
 msgstr ""
 
@@ -26447,6 +26453,9 @@ msgstr ""
 msgid "WikiEmpty|You must be a project member in order to add wiki pages."
 msgstr ""
 
+msgid "WikiEmpty|You've enabled the Confluence Workspace integration. Your wiki will be viewable directly within Confluence. We are hard at work integrating Confluence more seamlessly into GitLab. If you'd like to stay up to date, follow our %{wiki_confluence_epic_link_start}Confluence epic%{wiki_confluence_epic_link_end}."
+msgstr ""
+
 msgid "WikiHistoricalPage|This is an old version of this page."
 msgstr ""
 

spec/features/projects/confluence/user_views_confluence_page_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'User views the Confluence page' do
+  let_it_be(:user) { create(:user) }
+  let(:project) { create(:project, :public) }
+
+  before do
+    sign_in(user)
+  end
+
+  it 'shows the page when the Confluence integration is enabled' do
+    service = create(:confluence_service, project: project)
+
+    visit project_wikis_confluence_path(project)
+
+    element = page.find('.row.empty-state')
+
+    expect(element).to have_link('Go to Confluence', href: service.confluence_url)
+  end
+
+  it 'does not show the page when the Confluence integration disabled' do
+    visit project_wikis_confluence_path(project)
+
+    expect(page).to have_gitlab_http_status(:not_found)
+  end
+end

spec/views/layouts/nav/sidebar/_project.html.haml_spec.rb

@@ -120,7 +120,7 @@ RSpec.describe 'layouts/nav/sidebar/_project' do
       let(:active) { true }
 
       it 'shows the Confluence tab' do
-        expect(rendered).to have_link('Confluence', href: service.confluence_url)
+        expect(rendered).to have_link('Confluence', href: project_wikis_confluence_path(project))
       end
 
       it 'does not show the GitLab wiki tab' do