class UserRoles < ActiveRecord::Migration[5.0]
  def up
    unless table_exists?(:roles)
      create_table :roles do |t|
        t.string :name
      end
      create_table :roles_users, :id => false do |t|
        t.references :role
        t.references :user
      end
      add_index :roles_users, [:role_id, :user_id]
      add_index :roles_users, [:user_id, :role_id]
    end
  end

  def down
    drop_table :roles_users
    drop_table :roles
  end
end