class Cucumber::Events::Bus

def camel_case(underscored_name)
  underscored_name.to_s.split("_").map { |word| word.upcase[0] + word[1..-1] }.join
end

def constantize(camel_cased_word)
  names = camel_cased_word.split('::')
  # Trigger a built-in NameError exception including the ill-formed constant in the message.
  Object.const_get(camel_cased_word) if names.empty?
  # Remove the first blank element in case of '::ClassName' notation.
  names.shift if names.size > 1 && names.first.empty?
  names.inject(Object) do |constant, name|
    if constant == Object
      constant.const_get(name)
    else
      candidate = constant.const_get(name)
      next candidate if constant.const_defined?(name, false)
      next candidate unless Object.const_defined?(name)
      # Go down the ancestors to check if it is owned directly. The check
      # stops when we reach Object or the end of ancestors tree.
      constant = constant.ancestors.inject do |const, ancestor|
        break const    if ancestor == Object
        break ancestor if ancestor.const_defined?(name, false)
        const
      end
      # owner is in Object, so raise
      constant.const_get(name, false)
    end
  end
end

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

def initialize(default_namespace)
  @default_namespace = default_namespace.to_s
  @handlers = {}
end

def notify(event)
  handlers_for(event.class).each { |handler| handler.call(event) }
end

def parse_event_id(event_id)
  case event_id
  when Class
    return event_id
  when String
    constantize(event_id)
  else
    constantize("#{@default_namespace}::#{camel_case(event_id)}")
  end
end

def register(event_id, handler_object = nil, &handler_proc)
  handler = handler_proc || handler_object
  raise ArgumentError.new("Please pass either an object or a handler block") unless handler
  event_class = parse_event_id(event_id)
  handlers_for(event_class) << handler
end