From https://once.com/writebook

app/controllers/leafables_controller.rb

@@ -0,0 +1,69 @@
+class LeafablesController < ApplicationController
+  allow_unauthenticated_access only: :show
+
+  include SetBookLeaf
+
+  before_action :ensure_editable, except: :show
+  before_action :broadcast_being_edited_indicator, only: :update
+
+  def new
+    @leafable = new_leafable
+  end
+
+  def create
+    @leaf = @book.press new_leafable, leaf_params
+    position_new_leaf @leaf
+  end
+
+  def show
+  end
+
+  def edit
+  end
+
+  def update
+    @leaf.edit leafable_params: leafable_params, leaf_params: leaf_params
+
+    respond_to do |format|
+      format.turbo_stream { render }
+      format.html { head :no_content }
+    end
+  end
+
+  def destroy
+    @leaf.trashed!
+
+    respond_to do |format|
+      format.turbo_stream { render }
+      format.html { redirect_to book_slug_url(@book) }
+    end
+  end
+
+  private
+    def leaf_params
+      default_leaf_params.merge params.fetch(:leaf, {}).permit(:title)
+    end
+
+    def default_leaf_params
+      { title: new_leafable.model_name.human }
+    end
+
+    def new_leafable
+      raise NotImplementedError.new "Implement in subclass"
+    end
+
+    def leafable_params
+      raise NotImplementedError.new "Implement in subclass"
+    end
+
+    def position_new_leaf(leaf)
+      if position = params[:position]&.to_i
+        leaf.move_to_position position
+      end
+    end
+
+    def broadcast_being_edited_indicator
+      Turbo::StreamsChannel.broadcast_render_later_to @leaf, :being_edited,
+        partial: "leaves/being_edited_by", locals: { leaf: @leaf, user: Current.user }
+    end
+end