a11yist/app/models/checklist_entry.rb

# frozen_string_literal: true

class ChecklistEntry < ApplicationRecord
  belongs_to :checklist
  belongs_to :check

  before_validation :set_position
  before_update :update_positions, if: :position_changed?

  private
  def set_position
    self.position ||= (checklist.checklist_entries.pluck(:position).max || 0) + 1
  end

  def update_positions
    if position_was
      checklist.checklist_entries.where("position > ?", position_was).update_all("position = position - 1")
    end
    checklist.checklist_entries.where(position: position..).update_all("position = position + 1")
  end
end