Use Cases pattern spike - part 2

use_cases-base.rb

# 2. In order to enable that previous example of a handler to 
# deal with all of the transactions use cases, for a transactions
# controller, we'd need a base class that looks something like this:

module UseCases
  class Base

    class << self
      def commands
        @commands ||= {}
      end

      def permitted_use_cases
        commands.keys
      end

      def register_command(command_name, on:)
        commands[on] = command_name
      end
    end

    attr_reader :command_args, :listener

    def initialize(listener)
      @listener = listener
    end

    def execute(use_case, context: {}, on_success:, on_failure:)
      raise CommandNotPermitted unless permitted_use_cases.include?(use_case)

      build_command_args(context, on_success, on_failure)
      call_command_for use_case
    end

    def permitted_use_cases
      self.class.permitted_use_cases
    end


    private

    def build_command_args(context, on_success, on_failure)
      @command_args ||= {
        listener: listener,
        on_success: on_success,
        on_failure: on_failure
      }.merge!(context)
    end

    def call_command_for(use_case)
      case command_name = command_names(use_case)
      when String
        command_name.constantize.new(command_args).call
      when Symbol
        send command_name
      end
    end

    def commands
      self.class.commands
    end

    def failure(failure_return_value=nil)
      listener.send command_args[:on_failure], failure_return_value
    end

    def success(success_return_value=nil)
      listener.send command_args[:on_success], success_return_value
    end

  end
end

# part 3: https://gist.github.com/RichardJordan/cad1513c121796259bcfe097bf269b22