class ActionDispatch::MiddlewareStack

def active
  ActiveSupport::Deprecation.warn "All middlewares in the chain are active since the laziness " <<
    "was removed from the middleware stack", caller
end

def assert_index(index, where)
  i = index.is_a?(Integer) ? index : self.index(index)
  raise "No such middleware to insert #{where}: #{index.inspect}" unless i
  i
end

def build(app = nil, &block)
  app ||= block
  raise "MiddlewareStack#build requires an app" unless app
  reverse.inject(app) { |a, e| e.build(a) }
end

def initialize(*args, &block)
  super(*args)
  block.call(self) if block_given?
end

def insert(index, *args, &block)
  index = assert_index(index, :before)
  middleware = self.class::Middleware.new(*args, &block)
  super(index, middleware)
end

def insert_after(index, *args, &block)
  index = assert_index(index, :after)
  insert(index + 1, *args, &block)
end

def swap(target, *args, &block)
  insert_before(target, *args, &block)
  delete(target)
end

def use(*args, &block)
  middleware = self.class::Middleware.new(*args, &block)
  push(middleware)
end