/*
 * Copyright (c) 2012 Benjamin Franzke <benjaminfranzke@googlemail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

:-initialization(start).

pay(c,d,1).
pay(d,d,2).
pay(c,c,3).
pay(d,c,4).

pay2(A, B, PayA, PayB) :-
	pay(A, B, PayA),
	pay(B, A, PayB).

% Use opponents last decision
tit4tat_select(H,[H|_]).
% Fallback to coorporate at beginning
tit4tat_select(c,[]).

tit4tat(A, Hist, PayA, PayB) :-
	tit4tat_select(Old, Hist),
	pay2(A, Old, PayA, PayB).

sum([], 0).
sum([H|T], S) :- sum(T, TMP), S is TMP + H.

do(e, _, _, _) :- !.
do(Choice, Hist, PayedA, PayedB) :-
	tit4tat(Choice, Hist, PayA, PayB),

	write('A Pay: '), write(PayA), write('\t'),
	write('B Pay: '), write(PayB), write('\t'),
	write('A: '), sum([PayA|PayedA], SumA), write(SumA), write('\t'),
	write('B: '), sum([PayB|PayedB], SumB), write(SumB), nl,
	write(Choice),nl,

	loop([Choice|Hist], [PayA|PayedA], [PayB|PayedB]).

loop(Hist, PayedA, PayedB) :-
	write('Type c,d or e to end: '), read(Choice),
	do(Choice, Hist, PayedA, PayedB).

start :- loop([], [], []), halt.