import java.util.concurrent.Callable;

/**

* The LookAheadMoveThread objects are what is launched for each move the current player has.

* They implement the minimax algorithm as well as the alpha-beta pruning. They have timeouts

* and will return the best move they've seen so far if it expires.

*/

public class LiteMoveThread implements Callable<BestMove> {

private final LiteMinimax minimax;

private final LiteBoard origBoard;

private final boolean maximize;

private final LiteBoard board;

private final BestMove best;

private final int depth;

private final Move move;

LiteMoveThread(final LiteBoard orig, final LiteMinimax minimax, boolean maximize, final Move move, int depth) {

this.best = new BestMove(maximize);

this.maximize = maximize;

this.minimax = minimax;

this.origBoard = orig;

this.depth = depth;

this.move = move;

this.board = new LiteBoard(orig);

this.board.executeMove(move);

this.board.advanceTurn();

this.minimax.addNumMovesExamined(1);

}

// This call is made to us when we are launched

@Override

public BestMove call() {

Thread.yield();

int lookAheadVal = minimax.minmax(board, LiteUtil.MIN_VALUE, LiteUtil.MAX_VALUE,

depth - 1, !maximize);

if ((maximize && lookAheadVal >= best.value) || (!maximize && lookAheadVal <= best.value)) {

best.value = lookAheadVal;

best.move = move;

best.move.setValue(best.value);

minimax.cachedMoves.addMoveValue(origBoard.board, maximize, best.move, best.value, 1);

}

return best;

}

}