EventEmitterCore

event_emitter_core.rb

# the module can be included to any class
module EventEmitterCore
  # turn on the event
  # @param event_name [String, Symbol]
  def on(event_name)
    events[event_name.to_sym] ||= []
  end

  # turn off the event
  # @param event_name [String, Symbol]
  def off(event_name)
    events.delete(event_name.to_sym)
  end

  # subscribe to event
  # @param event_name [String, Symbol]
  # @param handler_proc [Proc]
  #   Proc with [Symbol, Object]
  def subscribe(event_name, handler_proc)
    handler_id = "#{event_name}_#{handler_proc.object_id}"
    events[event_name.to_sym]&.push(
      { id: handler_id, proc: handler_proc }
    )
    handler_id
  end

  # unsubscribe to event
  # @param event_name [String, Symbol]
  # @param handler [Proc]
  #   Proc with [Symbol, User]
  def unsubscribe(event_name, handler_id)
    events[event_name.to_sym]&.reject! do |item|
      item[:id] == handler_id
    end
  end

  # emit the event
  # @param event_name [String, Symbol]
  def emit(event_name)
    events[event_name.to_sym]&.each do |h|
      h[:proc].call(event_name.to_sym, self)
    end
  end

  # get array of existing events
  # @return [Array<Symbols>]
  def all_events
    events.keys
  end

  # get array of existing events with stat
  # @return [Array<Symbols, Fixnum>]
  def all_events_with_stat
    events
      .map { |name, arr| [name, arr.size] }
      .flatten
  end

  private

  def events
    @events ||= {}
  end
end