class Event::Bus

def initialize(resolver)
  @resolver = resolver
  @handlers = Hash.new { |h, k| h[k] = [] }
end

def notify(event)
  fail NoEventError, 'Please pass an event object, not a class' if event.is_a?(Class)
  @handlers[event.class.to_s].each { |handler| handler.call(event) }
end

def register(event_ids, handler_object = nil, &handler_proc)
  handler = handler_proc || handler_object
  fail ArgumentError, 'Please pass either an object#call or a handler block' if handler.nil? || !handler.respond_to?(:call)
  Array(event_ids).flatten.each do |id|
    event_class = @resolver.transform(id)
    fail EventNameResolveError, %(Transforming "#{id}" into an event name failed for unknown reason.) if event_class.nil?
    @handlers[event_class.to_s] << handler
  end
  nil
end