Allow Blacklight to define Stimulus controllers

config/importmap.rb

@@ -1,3 +1,4 @@
 # frozen_string_literal: true
 
 pin_all_from File.expand_path("../app/javascript/blacklight", __dir__), under: "blacklight"
+pin_all_from File.expand_path("../app/javascript/controllers", __dir__), under: "controllers"

lib/railties/blacklight.rake

@@ -119,3 +119,18 @@ namespace :blacklight do
     end
   end
 end
+
+if Rake::Task.task_defined?('stimulus:manifest:display')
+  Rake::Task['stimulus:manifest:display'].enhance do
+    puts Stimulus::Manifest.generate_from(Blacklight::Engine.root.join("app/javascript/controllers")).join("\n").gsub('./blacklight/', 'blacklight-frontend/app/javascript/controllers/blacklight/')
+  end
+end
+
+if Rake::Task.task_defined?('stimulus:manifest:update')
+  Rake::Task['stimulus:manifest:update'].enhance do
+    manifest = Stimulus::Manifest.generate_from(Blacklight::Engine.root.join("app/javascript/controllers")).join("\n").gsub('./blacklight/', 'blacklight-frontend/app/javascript/controllers/blacklight/')
+    File.open(Rails.root.join("app/javascript/controllers/index.js"), "a+") do |index|
+      index.puts manifest
+    end
+  end
+end

package.json

@@ -30,6 +30,7 @@
     "not IE 11"
   ],
   "dependencies": {
+    "@hotwired/stimulus": "^3.2.1",
     "bootstrap": ">=4.3.1 <6.0.0"
   }
 }