class Cucumber::Core::EventBus

def broadcast(event)
  raise ArgumentError, "Event type #{event.class} is not registered. Try one of these:\n#{event_types.values.join("\n")}" unless registered_type?(event.class)
  handlers_for(event.class).each { |handler| handler.call(event) }
  @event_queue << event
end

def broadcast_queued_events_to(handler, event_type)
  @event_queue.select { |event| event.instance_of?(event_type) }.each { |event| handler.call(event) }
end

def handlers_for(event_class)
  @handlers[event_class.to_s] ||= []
end

def initialize(registry = Events.registry)
  @event_types = registry.freeze
  @handlers = {}
  @event_queue = []
end

def method_missing(event_id, *args)
  event_class = event_types.fetch(event_id) { super }
  broadcast event_class.new(*args)
end

def on(event_id, handler_object = nil, &handler_proc)
  handler = handler_proc || handler_object
  validate_handler_and_event_id!(handler, event_id)
  event_class = event_types[event_id]
  handlers_for(event_class) << handler
  broadcast_queued_events_to handler, event_class
end

def registered_id?(event_id)
  event_types.keys.include?(event_id)
end

def registered_type?(event_type)
  event_types.values.include?(event_type)
end

def respond_to_missing?(event_id, *args)
  event_types.key?(event_id) || super
end

def validate_handler_and_event_id!(handler, event_id)
  raise ArgumentError, 'Please pass either an object or a handler block' unless handler
  raise ArgumentError, 'Please use a symbol for the event_id' unless event_id.is_a?(Symbol)
  raise ArgumentError, "Event ID #{event_id} is not recognised. Try one of these:\n#{event_types.keys.join("\n")}" unless registered_id?(event_id)
end