module ::ScottBarron                 #:nodoc:
  module Acts                        #:nodoc:
    module StateMachine              #:nodoc:
      module SupportingClasses
        class Event
          # Patching the fire method so that if you try to invoke an event on a record in a state
          # where the event is not available we throw an exception. Without this patch, invoking
          # say user.activate! on a user that is already active would do nothing and return an empty list.
          def fire(record)            
            raise("Cannot invoke event #{name} on #{record.class.name}:#{record.id} since " +
              "it is not available in state #{record.current_state}") if next_states(record).blank?
            next_states(record).each do |transition|
              return true if transition.perform(record)
            end
            raise("Could not invoke event #{name} on #{record.class.name}:#{record.id} " +
              "in state #{record.current_state} - probably because a guard condition was not met")
          end
        end
      end

      module InstanceMethods
        # List events (transitions) available in the current state
        def current_events
          self.class.transition_table.keys.select do |event|
            self.class.transition_table[event].detect do |transition|
              transition.from == current_state
            end
          end
        end
      end
    end
  end
end