-module(fsm_telephone).
-export([start/1, call/2, ringing/2,idle/1, dial/1, connected/1, start_ringing/0, start_tone/0, stop_ringing/0]).
-export([init/0]).

start(Name) ->
 ets:new(bill, [bag]),
 Pid = spawn(fsm_telephone, init, []),
 register(Name, Pid), ok.

init() ->
    Bill = ets:new(bill, [bag]),
    idle(Bill).

call(Name, Msg) ->
 Name ! {request, self(), Msg}.

idle(Bill) ->
 receive
 {Number, incoming} ->
 start_ringing(),
 ringing(Number, Bill);
 {Number,off_hook} ->
 start_tone(),
 ets:insert(Bill, Number),
 dial(Bill);
 {PID, bill} ->
 PID ! ets:lookup(Bill)
 end.

ringing(Number, Bill) ->
 receive
 {Number, other_on_hook} ->
 stop_ringing(),
 idle(Bill);
 {Number, off_hook} ->
 stop_ringing(),
 connected(Bill)
 end.

dial(Bill) ->
 receive
 on_hook ->
 idle(Bill);
 connect ->
 connected(Bill)
 end.

connected(Bill) ->
 receive
 on_hook ->
 idle(Bill)
 end.

start_ringing() -> ringing.
start_tone() -> tone.
stop_ringing() -> stopRinging.