:- package(gui).
:- package(guibuilder).

:- dynamic([ui_window/1]).

main(Applet, _) :-
	appletButtons(Applet),
	newCalculator.

newCalculator :-
	frame_create(Frame),
	frame_setTitle(Frame, 'MINERVA: Calculator'),
	font_create('Helvetica', bold, 24, Font1),
	component_setFont(Frame, Font1),
	gui(Frame, border, [
		'North' / text_field(CalcResult),
		'Center' / panel(_, grid(4,5), [
			button(_,'off') ** action(calcAction(Frame,'off')),
			button(_,'7') ** action(calcAction(Frame,'7')),
			button(_,'8') ** action(calcAction(Frame,'8')),
			button(_,'9') ** action(calcAction(Frame,'9')),
			button(_,'/') ** action(calcAction(Frame,'/')),
			button(_,''),
			button(_,'4') ** action(calcAction(Frame,'4')),
			button(_,'5') ** action(calcAction(Frame,'5')),
			button(_,'6') ** action(calcAction(Frame,'6')),
			button(_,'*') ** action(calcAction(Frame,'*')),
			button(_,'C') ** action(calcAction(Frame,'C')),
			button(_,'1') ** action(calcAction(Frame,'1')),
			button(_,'2') ** action(calcAction(Frame,'2')),
			button(_,'3') ** action(calcAction(Frame,'3')),
			button(_,'-') ** action(calcAction(Frame,'-')),
			button(_,'AC') ** action(calcAction(Frame,'AC')),
			button(_,'0') ** action(calcAction(Frame,'0')),
			button(_,'.') ** action(calcAction(Frame,'.')),
			button(_,'=') ** action(calcAction(Frame,'=')),
			button(_,'+') ** action(calcAction(Frame,'+'))
			])
		]),
	assertz(ui_window(Frame)),
	InitCalcState = cs([],'0','ok'),
	set_global(Frame, CalcResult/InitCalcState),
	textComponent_setEditable(CalcResult,false),
	calcShow(CalcResult, InitCalcState),
	frame_pack(Frame),
	component_setVisible(Frame, true),
	!.

appletButtons(Applet) :-
	font_create('Helvetica',bold,20,Font1),
	component_setFont(Applet,Font1),
	gui(Applet, grid(1,2), [
		button(_,'new calculator') ** action(newCalculator),
		button(_,'dismiss') ** action(dismissAll)
	]).

%%% Calculator Engine: implemented as automaton
calcKey('1',digit).
calcKey('2',digit).
calcKey('3',digit).
calcKey('4',digit).
calcKey('5',digit).
calcKey('6',digit).
calcKey('7',digit).
calcKey('8',digit).
calcKey('9',digit).
calcKey('0',digit).
calcKey('.',digit).
calcKey('+',bin_op).
calcKey('*',bin_op).
calcKey('/',bin_op).
calcKey('-',bin_op).
calcKey('=',other_op).
calcKey('AC',other_op).
calcKey('C',other_op).
calcKey('off',other_op).

calcAction(Frame,Key) :-
	get_global(Frame, Field/CalcState1),
	calcKey(Key,Kind), !,
	calcTrans(Key,Kind,Frame,CalcState1,CalcState2),
	calcShow(Field, CalcState2),
	set_global(Frame, Field/CalcState2).

% State transition: calcTrans(Key,Kind,CalcState1,CalcState2)
% Single state:     CalcState = cs(Stack,Display,Status)

calcTrans('=',_K,_,cs([Num2,Op,Num|S],_D,done),cs([Result|S],NewD,done)) :- !,
	calcApply(Num,Op,Num2,Result), calcDisplayNumber(NewD,Result).
calcTrans('=',_Kind,_,cs([Op,Num|S],D,ok),cs([Result|S],NewD,done)) :-
	calcDisplayNumber(D,Num2), calcApply(Num,Op,Num2,Result),
	calcDisplayNumber(NewD,Result),!.
calcTrans(Key,bin_op,_,cs([Op,Num|S],D,ok),cs([Key,Result|S],NewD,op)) :-
	calcDisplayNumber(D,Num2), calcApply(Num,Op,Num2,Result),
	calcDisplayNumber(NewD1,Result),atom_concat(NewD1,Key,NewD),!.
calcTrans(Key,bin_op,_,cs(S,D,done),cs([Key,Number|S],NewD,op)) :- !,
	calcDisplayNumber(D,Number), atom_concat(D,Key,NewD),!.
calcTrans(Key,Kind,F,cs(S,_D,done),cs(S,NewD,NewState)) :-
	calcTrans(Key,Kind,F,cs(S,'0',ok),cs(S,NewD,NewState)).
calcTrans(Key,bin_op,_,cs(S,D,ok),cs([Key,Number|S],NewD,op)) :-
	calcDisplayNumber(D,Number), atom_concat(D,Key,NewD),!.
calcTrans('.',digit,_,cs(S,'0',ok),cs(S,'0.',ok)) :- !.
calcTrans('.',digit,_,cs(S,D,ok),cs(S,NewD,ok)) :-
	atom_chars(D,DisplayChars), \+ member('.',DisplayChars),!,
	atom_concat(D,'.',NewD).
calcTrans('.',digit,_,cs(S,D,ok),cs(S,D,ok)) :-
	atom_chars(D,DisplayChars), member('.',DisplayChars),!.
calcTrans(Key, digit,_,cs(S,'0',ok),cs(S,Key,ok)) :-  !.
calcTrans(Key, digit,_,cs(S,D,ok),cs(S,NewD,ok)) :-  !,
	atom_concat(D,Key,NewD),!.
calcTrans(Key,digit,_,cs(S,_D,op),cs(S,Key,ok)) :- !.
calcTrans(' AC ',_Kind,_,cs(_S,_D,_Status),cs([],'0',ok)) :- !.
calcTrans('C',_Kind,_,cs(S,_D,_Status),cs(S,'0','ok')) :- !.
calcTrans('off',_Kind,F,cs(S,_D,_Status),cs(S,'0','ok')) :-
	retract(ui_window(F)), frame_dispose(F), !.
calcTrans(Key,_Kind,CalcState,CalcState) :-
	writeq(ignored(Key,CalcState)),nl,flush_output.

calcShow(Field, cs(_,Display,_)) :-
	% writeq(cs(Stack,Display,Status)), nl, flush_output,
	textComponent_setText(Field, Display).

calcApply(Num,Op,Num2,Result) :-
	Formula =.. [Op,Num,Num2], Result is Formula.

% calcDisplayNumber(Display,Number) :-
calcDisplayNumber('',0) :- !.
calcDisplayNumber(Display,Number) :- atom_number(Display,Number).

%%% Calculator GUI 

dismissAll :-
	retract(ui_window(F)),
	frame_dispose(F),
	fail.
dismissAll.