chain.rb

# encoding: utf-8

module ChainOfResponsibility
  attr_writer :successor

  def can_handle_request?(request); end
  def do_handle(request); end

  def handle_request(request)
    if can_handle_request?(request)
      do_handle(request)
    elsif !@successor.nil?
      @successor.handle_request(request)
    end
  end
end

class Carro
  include ChainOfResponsibility

  def can_handle_request?(request)
    request.weight < 1500
  end

  def do_handle(request)
    puts "Um carro é o suficiente para locomover: #{request.weight}"
  end
end

class Caminhonete
  include ChainOfResponsibility

  def can_handle_request?(request)
    request.weight < 3000
  end

  def do_handle(request)
    puts "Uma caminhonete é o suficiente para locomover: #{request.weight}"
  end

end

class Caminhao
  include ChainOfResponsibility

  def can_handle_request?(request)
    request.weight < 5000
  end

  def do_handle(request)
    puts "Um caminhão é o suficiente para locomover: #{request.weight}"
  end
end


class Request
  attr_reader :weight

  def initialize(weight)
    @weight = weight
  end
end

class Handler
  def initialize
    initialize_handlers
    setup_successors
  end

  def handle_request(request)
    initial_handler.handle_request(request)
  end

  private

  def initialize_handlers
    @carro = Carro.new
    @caminhonete = Caminhonete.new
    @caminhao = Caminhao.new
  end

  def setup_successors
    @carro.successor = @caminhonete
    @caminhonete.successor = @caminhao
  end

  def initial_handler
    @carro
  end
end

handler = Handler.new

request = Request.new(1000)
handler.handle_request(request)

request = Request.new(2500)
handler.handle_request(request)

request = Request.new(4500)
handler.handle_request(request)