module Emittable

# File lib/emittable.rb, line 6
def initialize(*args)
  @emittable_setup = true
  @emittable_events = {}
  @emittable_mutex = Mutex.new
  super(*args)
end

# File lib/emittable.rb, line 31
def off(event_name, callback)
  check_emittable_setup
  raise ArgumentError, "event name must respond to 'to_s'" unless event_name.respond_to?(:to_s)
  event_name = event_name.to_s
  @emittable_mutex.synchronize do
    callbacks = @emittable_events[event_name]
    raise Error, 'no callbacks found for that event' unless callbacks
    raise Error, 'callback not found' unless callbacks.include?(callback)
    callbacks.delete(callback)
    @emittable_events.delete(event_name) if callbacks.empty?
  end
  nil
end

# File lib/emittable.rb, line 19
def on(event_name, &callback)
  check_emittable_setup
  raise ArgumentError, "event name must respond to 'to_s'" unless event_name.respond_to?(:to_s)
  event_name = event_name.to_s
  @emittable_mutex.synchronize do
    @emittable_events[event_name] ||= []
    callbacks = @emittable_events[event_name]
    callbacks << callback
  end
  nil
end

# File lib/emittable.rb, line 52
def trigger(event_name, *args)
  check_emittable_setup
  raise ArgumentError, "event name must respond to 'to_s'" unless event_name.respond_to?(:to_s)
  event_name = event_name.to_s
  callbacks = nil
  @emittable_mutex.synchronize do
    callbacks = @emittable_events[event_name].to_a
    callbacks = callbacks.dup # in case the array changes as we are iterating through the callbacks
  end
  # we are outside of the mutex so any callbacks are able to trigger an event from
  #  this class without deadlock
  callbacks.each { |callback| callback.call(*args) }
  nil
end

# File lib/emittable.rb, line 69
def check_emittable_setup
  raise Error, "has 'super' been called on including class?" unless @emittable_setup
  nil
end