# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def create
    Operations::User::Create.new.call(params[:user]) do |m|
      m.success do |user_response|
        render json: user_response
      end

      m.failure do |responce|
        render json: responce, status: :not_acceptable
      end
    end
  end
end

# app/operations/user/create.rb
require 'dry/transaction'

module Operations::User
  class Create
    include Dry::Transaction
    include Dry::Monads::List::Mixin

    VALIDATOR = Dry::Validation.Schema do
      required(:nickname).filled
      required(:email).filled
      required(:password).filled
    end

    ALLOW_PARAMS = ::User.column_names.freeze
    DENY_PARAMS  = %i[id].freeze

    step :validate
    step :clean
    try :persist, catch: StandardError
    tee :log_data

    def validate(user)
      result = VALIDATOR.call(user)
      result.success? ? Right(result) : Left(result.errors)
    end

    def clean(user)
      Right(user.output.select! { |k, _v| ALLOW_PARAMS.include? k }.permit!.except(*DENY_PARAMS))
    end

    def persist(user)
      ::User.create(user)
    end

    def log_data(user)
      Rails.logger.info user.inspect
    end
  end
end