/* 

  Tic-tac benchmark in Picat.

  From
  http://www.jekejeke.ch/idatab/doclet/prod/en/docs/05_run/15_stdy/06_bench/09_programs/06_tictac/01_tictac.p.html

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


import util.
% import cp.


main => go.



/**
 * Prolog code for the tic-tac-toe game.
 *
 * Min-max search via negation.
 *
 * Copyright 2011-2012, XLOG Technologies GmbH, Switzerland
 * Jekejeke Prolog 0.9.1 (a fast and small prolog interpreter)
 */

% move(+Board,+Player,-Board)
move([[-,B,C],[D,E,F],[G,H,I]],P,M2) ?=> M2=[[P,B,C],[D,E,F],[G,H,I]].
move([[A,-,C],[D,E,F],[G,H,I]],P,M2) ?=> M2=[[A,P,C],[D,E,F],[G,H,I]].
move([[A,B,-],[D,E,F],[G,H,I]],P,M2) ?=> M2=[[A,B,P],[D,E,F],[G,H,I]].
move([[A,B,C],[-,E,F],[G,H,I]],P,M2) ?=> M2=[[A,B,C],[P,E,F],[G,H,I]].
move([[A,B,C],[D,-,F],[G,H,I]],P,M2) ?=> M2=[[A,B,C],[D,P,F],[G,H,I]].
move([[A,B,C],[D,E,-],[G,H,I]],P,M2) ?=> M2=[[A,B,C],[D,E,P],[G,H,I]].
move([[A,B,C],[D,E,F],[-,H,I]],P,M2) ?=> M2=[[A,B,C],[D,E,F],[P,H,I]].
move([[A,B,C],[D,E,F],[G,-,I]],P,M2) ?=> M2=[[A,B,C],[D,E,F],[G,P,I]].
move([[A,B,C],[D,E,F],[G,H,-]],P,M2) => M2=[[A,B,C],[D,E,F],[G,H,P]].

% init(+Board)
init(B) => B=[[-,-,-],[-,-,-],[-,-,-]].

% win(+Board,+Player)
win([[P,P,P],[_,_,_],[_,_,_]],P) => true.
win([[_,_,_],[P,P,P],[_,_,_]],P) => true.
win([[_,_,_],[_,_,_],[P,P,P]],P) => true.
win([[P,_,_],[P,_,_],[P,_,_]],P) => true.
win([[_,P,_],[_,P,_],[_,P,_]],P) => true.
win([[_,_,P],[_,_,P],[_,_,P]],P) => true.
win([[P,_,_],[_,P,_],[_,_,P]],P) => true.
win([[_,_,P],[_,P,_],[P,_,_]],P) => true.

% other(+Player,-Player).
other(o,P2) => P2=x.
other(x,P2) => P2=o.

% tie(+Board,+Player)
tie(X,P) =>
  not move(X,P,_).

% best(+Board,+Player,-Board)
best(X,P,Y) =>
  move(X,P,Y),
  (win(Y,P) -> true;
    other(P,Q),
    not tie(Y,Q),
    not best(Y,Q,_)).

% Should fail
tictac =>
  init(X), 
  best(X,x,_),
  writeln(X).

tictac2 =>
  init(X), 
  best(X,x,_).

% go => tictac -> writeln(ok) ; writeln (nope).
go => tictac.
% go2 => tictac -> write(ok) ; write(nope).