From https://once.com/writebook

app/controllers/books/leaves/moves_controller.rb

@@ -0,0 +1,19 @@
+class Books::Leaves::MovesController < ApplicationController
+  include BookScoped
+
+  before_action :ensure_editable
+
+  def create
+    leaf, *followed_by = leaves
+    leaf.move_to_position(position, followed_by: followed_by)
+  end
+
+  private
+    def position
+      params[:position].to_i
+    end
+
+    def leaves
+      @book.leaves.find(Array(params[:id]))
+    end
+end