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

start(Name) ->
 Bill = [],
 Pid = spawn(fsm_telephone, idle, [Bill]),
 register(Name, Pid), ok.

call(Name, Msg) ->
 Name ! {request, self(), Msg},
 receive {reply, Reply} -> Reply end.

reply(To, Msg) ->
 To ! {reply, Msg}.

idle(Bill) ->
 receive
 {request, From, {Number, incoming}} ->
 start_ringing(From),
 ringing(Number, Bill);
 {request, From, {Number, call}} ->
 start_tone(From),
 dial(Number, Bill);
 {request, From, bill} ->
 reply(From, 'Billing'),
 io:format("~w~n", [Bill]),
 idle(Bill)
 end.

ringing(Number, Bill) ->
 receive
 {request, From, other_on_hook} ->
 stop_ringing(From),
 idle(Bill);
 {request, From, off_hook} ->
 stop_ringing(From),
 {{Year,Month,Day},{Hour,Min,Sec}} = erlang:localtime(),
 Bill1 = Bill++[{'Incoming call', Number, {{Year,Month,Day},{Hour,Min,Sec}}}],
 connected(Bill1)
 end.

dial(Number, Bill) ->
 receive
 {request, From, on_hook} ->
 reply(From, 'Cancel calling'),
 idle(Bill);
 {request, From, connect} ->
 {{Year,Month,Day},{Hour,Min,Sec}} = erlang:localtime(),
 Bill1 = Bill++[{'Outcoming call', Number, {{Year,Month,Day},{Hour,Min,Sec}}}],
 reply(From, connected),
 connected(Bill1)
 end.

connected(Bill) ->
 receive
 {request, From, on_hook} ->
 reply(From, 'Calling finished!!!'),
 {{Year,Month,Day},{Hour,Min,Sec}} = erlang:localtime(),
 Bill1 = Bill++[{'End Call', {{Year,Month,Day},{Hour,Min,Sec}}}],
 idle(Bill1)
 end.

start_ringing(To) -> reply(To, 'Ring ring!!!').
start_tone(To) -> reply(To, 'Signal tone!!!').
stop_ringing(To) -> reply(To, 'Stop ringing').