Show confluence CTA on project wiki empty state

When viewing an empty wiki, an admin will now be prompted to activate
the Confluence service.

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

app/assets/stylesheets/pages/wiki.scss

@@ -147,3 +147,7 @@ ul.wiki-pages-list.content-list {
     }
   }
 }
+
+.empty-state-wiki .text-content {
+  max-width: 490px; // Widen to allow for the Confluence button
+}

app/helpers/wiki_helper.rb

@@ -95,10 +95,13 @@ module WikiHelper
   def wiki_empty_state_messages(wiki)
     case wiki.container
     when Project
+      writable_body = s_("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.")
+      writable_body += s_("WikiEmpty| Have a Confluence wiki already? Use that instead.") if show_enable_confluence_integration?(wiki.container)
+
       {
         writable: {
           title: s_('WikiEmpty|The wiki lets you write documentation for your project'),
-          body: s_("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.")
+          body: writable_body
         },
         issuable: {
           title: s_('WikiEmpty|This project has no wiki pages'),
@@ -137,4 +140,10 @@ module WikiHelper
       'wiki-directory-nest-level' => page.path.scan('/').count
     }
   end
+
+  def show_enable_confluence_integration?(container)
+    container.is_a?(Project) &&
+      current_user&.can?(:admin_project, container) &&
+      !container.has_confluence?
+  end
 end

app/views/shared/empty_states/_wikis.html.haml

@@ -11,6 +11,10 @@
     %p.text-left
       = messages.dig(:writable, :body)
     = create_link
+    - if show_enable_confluence_integration?(@wiki.container)
+      = link_to s_('WikiEmpty|Enable the Confluence Wiki integration'),
+          edit_project_service_path(@project, :confluence),
+          class: 'btn', title: s_('WikiEmpty|Enable the Confluence Wiki integration')
 
 - elsif @project && can?(current_user, :read_issue, @project)
   - issues_link = link_to s_('WikiEmptyIssueMessage|issue tracker'), project_issues_path(@project)

app/views/shared/empty_states/_wikis_layout.html.haml

-.row.empty-state
+.row.empty-state.empty-state-wiki
   .col-12
     .svg-content.qa-svg-content
       = image_tag image_path

locale/gitlab.pot

@@ -26396,6 +26396,9 @@ msgstr ""
 msgid "WikiEmptyIssueMessage|issue tracker"
 msgstr ""
 
+msgid "WikiEmpty| Have a Confluence wiki already? Use that instead."
+msgstr ""
+
 msgid "WikiEmpty|A wiki is where you can store all the details about your group. This can include why you've created it, its principles, how to use it, and so on."
 msgstr ""
 
@@ -26405,6 +26408,9 @@ msgstr ""
 msgid "WikiEmpty|Create your first page"
 msgstr ""
 
+msgid "WikiEmpty|Enable the Confluence Wiki integration"
+msgstr ""
+
 msgid "WikiEmpty|Suggest wiki improvement"
 msgstr ""
 

spec/features/projects/wiki/user_views_wiki_empty_spec.rb

@@ -4,18 +4,19 @@ require 'spec_helper'
 
 RSpec.describe 'User views empty wiki' do
   let(:user) { create(:user) }
+  let(:confluence_link) { 'Enable the Confluence Wiki integration' }
+  let(:element) { page.find('.row.empty-state') }
 
   shared_examples 'empty wiki and accessible issues' do
     it 'show "issue tracker" message' do
       visit(project_wikis_path(project))
 
-      element = page.find('.row.empty-state')
-
       expect(element).to have_content('This project has no wiki pages')
       expect(element).to have_content('You must be a project member')
       expect(element).to have_content('improve the wiki for this project')
       expect(element).to have_link("issue tracker", href: project_issues_path(project))
       expect(element).to have_link("Suggest wiki improvement", href: new_project_issue_path(project))
+      expect(element).to have_no_link(confluence_link)
     end
   end
 
@@ -23,11 +24,10 @@ RSpec.describe 'User views empty wiki' do
     it 'does not show "issue tracker" message' do
       visit(project_wikis_path(project))
 
-      element = page.find('.row.empty-state')
-
       expect(element).to have_content('This project has no wiki pages')
       expect(element).to have_content('You must be a project member')
       expect(element).to have_no_link('Suggest wiki improvement')
+      expect(element).to have_no_link(confluence_link)
     end
   end
 
@@ -60,16 +60,15 @@ RSpec.describe 'User views empty wiki' do
   end
 
   context 'when user is logged in and a member' do
-    let(:project) { create(:project, :public, :wiki_repo) }
+    let(:project) { create(:project, :public) }
 
     before do
       sign_in(user)
       project.add_developer(user)
     end
 
-    it 'show "create first page" message' do
+    it 'shows "create first page" message' do
       visit(project_wikis_path(project))
-      element = page.find('.row.empty-state')
 
       expect(element).to have_content('your project', count: 2)
 
@@ -77,5 +76,34 @@ RSpec.describe 'User views empty wiki' do
 
       expect(page).to have_button('Create page')
     end
+
+    it 'does not show the "enable confluence" button' do
+      visit(project_wikis_path(project))
+
+      expect(element).to have_no_link(confluence_link)
+    end
+  end
+
+  context 'when user is logged in and an admin' do
+    let(:project) { create(:project, :public, :wiki_repo) }
+
+    before do
+      sign_in(user)
+      project.add_maintainer(user)
+    end
+
+    it 'shows the "enable confluence" button' do
+      visit(project_wikis_path(project))
+
+      expect(element).to have_link(confluence_link)
+    end
+
+    it 'does not show "enable confluence" button if confluence is already enabled' do
+      create(:confluence_service, project: project)
+
+      visit(project_wikis_path(project))
+
+      expect(element).to have_no_link(confluence_link)
+    end
   end
 end