cat_fsm.erl

-module(cat_fsm).
-behaviour(gen_fsm).

% gen_fsm behavior implementation
-export([ init/1, handle_event/3, handle_sync_event/4, handle_info/3, terminate/3, code_change/4]).
% states
-export([ dont_give_crap/3]).
% test
-export([ test/0]).


%% client stuff

event(Pid, Event) -> 
  gen_fsm:sync_send_event(Pid, Event, 5000).

%% gen_fsm chrome

init(_State) ->
  {ok, dont_give_crap, []}.

terminate(Reason, StateName, _StateData) ->
  io:format("terminating with reason ~p at state ~p~n",[Reason, StateName]),
  ok.

code_change(_OldVsn, StateName, Data, _Extra) ->
 {ok, StateName, Data}.


handle_info(Info, StateName, Data) ->
   io:format("~p received unknown event ~p while in state ~p~n", [self(), Info, StateName]),
   {next_state, StateName, Data}.


%% State Transitions

dont_give_crap(_Event, _From, StateData) ->
  io:format("Switching to 'dont_give_crap' state~n"),
  {reply, ok, dont_give_crap, StateData}.


handle_event(shutdown, _StateName, StateData) ->
  {stop, normal, StateData};
handle_event(Event, StateName, StateData) ->
  io:format("Cat receives an unknown global event: ~p ~n", [Event]),
  {next_state, StateName, StateData}.


handle_sync_event(shutdown, _From, StateName, _StateData) ->
  {stop, normal, ok, StateName};
handle_sync_event(Event, _From, StateName, StateData) ->
  io:format("Cat receives an unknown global sync event: ~p ~n", [Event]),
  {reply, ok, StateName,StateData,5000}.


%% test

test() ->
  spawn(fun() ->
    {ok, Pid} = gen_fsm:start_link(?MODULE, [], []),
    
    lists:foreach(fun(Action)-> 
      Reply = event(Pid, Action),
      io:format("Cat replied: ~p ~n", [Reply])
    end, [pet, love, cherish]),
    
    gen_fsm:sync_send_all_state_event(Pid, hello),
    gen_fsm:send_all_state_event(Pid, how_are_you),
    
    gen_fsm:sync_send_all_state_event(Pid, shutdown)
  end).