Content of file GstKopplungNegaMax.java

package de.fhdw.gaming.ipspiel23.gst.strategies.impl;

import java.util.Collection;
import java.util.Optional;

import de.fhdw.gaming.core.domain.GameException;
import de.fhdw.gaming.core.domain.Move;
import de.fhdw.gaming.core.domain.Player;
import de.fhdw.gaming.core.domain.State;
import de.fhdw.gaming.ipspiel23.gst.domain.IKopplung;
import de.fhdw.gaming.ipspiel23.gst.strategies.domain.IGstKopplungsMiniMaxStrategy;

/**
 * An implementation of the IGstKopplungsMiniMaxStrategy interface using the
 * NegaMax algorithm with alpha beta pruning and Time based Iterative Deepening.
 *
 * @param <P> The type of player in the game.
 * @param <S> The type of state in the game.
 * @author borkowitz
 */
public class GstKopplungNegaMax<P extends Player<P>, S extends State<P, S>>
        implements IGstKopplungsMiniMaxStrategy<P, S> {

    /**
     * Calculates the best move for the current player of a Game in a given Game state using the NegaMax algorithm.
     * Too complex, but not easily simplifyable. Warning suppressed.
     *
     * @param kopplung               The game object representing the specific game being played.
     * @param state                  The current state of the game.
     * @param maximumComputationTime The maximum computation time allowed for calculating the move.
     * @return An optional containing the calculated best move, or empty if no move is available.
     */
    @SuppressWarnings({ "checkstyle:CyclomaticComplexity", "PMD.CyclomaticComplexity", "PMD.CognitiveComplexity" })
    @Override
    public Optional<Move<P, S>> calculateBestMove(final IKopplung<P, S> kopplung, final S state, // NOPMD by Dave on
                                                                                                 // 26.06.23, 22:57
            final int maximumComputationTime) {
        Optional<Move<P, S>> bestMove = Optional.empty();
        try {

            final Long startTime = System.currentTimeMillis();
            final Optional<Collection<Move<P, S>>> possiblesMovesOptional = kopplung.getPossibleMoves(state);

            if (possiblesMovesOptional.isPresent() && possiblesMovesOptional.get().size() > 0) {

                for (int i = 0;; i++) {
                    Integer bestMoveScore = Integer.MIN_VALUE;
                

                    Optional<Move<P, S>> iterationBestMove = Optional.empty();
                    Integer iterationBestMoveScore = Integer.MIN_VALUE;

                    if ((System.currentTimeMillis() - startTime) > (maximumComputationTime / 2)) {
                        break;
                    }

                    for (final Move<P, S> move : possiblesMovesOptional.get()) {

                        final S copiedState = state.deepCopy();
                        final P currentPlayer = kopplung.getCurrentPlayer(copiedState).get();
                        move.applyTo(copiedState, currentPlayer);
                        copiedState.nextTurn();

                        final Integer moveScore = -this.negamax(kopplung, copiedState, i, Integer.MIN_VALUE,
                                Integer.MAX_VALUE);

//                        System.out.println(copiedState);
//                        System.out.println(move);
//                        System.out.println(moveScore);
//                        System.out.println("");

                        // final Integer moveScore = simulateEvaluateMove(kopplung, state, i, move);

                        if (moveScore > iterationBestMoveScore) {

                            iterationBestMove = Optional.of(move);
                            iterationBestMoveScore = moveScore;
                        }
                    }
//                    System.out.println("");
//                    System.out.println("");
//                    System.out.println("________________");
                    if (iterationBestMoveScore > bestMoveScore) {
                        bestMove = iterationBestMove;
                        bestMoveScore = iterationBestMoveScore;
                    }
                }
            }
            return bestMove;
        } catch (final Exception e) {
            e.printStackTrace();
printStackTrace auf System.out nicht erlaubt.
Since Checkstyle 6.0

          This class is variation on RegexpSingleline for detecting
          single lines that match a supplied regular expression in Java files. It supports
          suppressing matches in Java comments.
        
            return bestMove;
        }

    }

    /**
     * Extracted.
     *
     * @param kopplung
     * @param state
     * @param move
     * @return
     * @throws GameException
     */
    private S simulateMove(final IKopplung<P, S> kopplung, final S state, final Move<P, S> move) throws GameException {
        final S copiedState = state.deepCopy();
        final P currentPlayer = kopplung.getCurrentPlayer(copiedState).get();
        move.applyTo(copiedState, currentPlayer);
        copiedState.nextTurn();
        return copiedState;
    }

    /**
     * Performs the NegaMax algorithm to evaluate the score of a Game state.
     * Too complex, but not easily simplifyable. Warning suppressed.
     *
     * @param kopplung The game object representing the specific game being played.
     * @param state    The current state of the game.
     * @param depth    The current depth of the algorithm.
     * @param alpha    The alpha value for alpha-beta pruning.
     * @param beta     The beta value for alpha-beta pruning.
     * @return The evaluated score of the state.
     * @throws Exception
     */
    @SuppressWarnings({ "checkstyle:CyclomaticComplexity", "PMD.CyclomaticComplexity", "PMD.CognitiveComplexity" })

    private Integer negamax(final IKopplung<P, S> kopplung, final S state, final Integer depth, final Integer alpha,
            final Integer beta) throws GameException {

        final Optional<Collection<Move<P, S>>> possiblesMovesOptional = kopplung.getPossibleMoves(state);

        if (depth == 0 || kopplung.getIsGameOver(state).get()) {

            return kopplung.evalState(state).get();
        }

        if (possiblesMovesOptional.isPresent() && possiblesMovesOptional.get().size() > 0) {

            Integer score = Integer.MIN_VALUE;
            Integer modAlpha = alpha;
            for (final Move<P, S> move : possiblesMovesOptional.get()) {

                final S copiedState = this.simulateMove(kopplung, state, move);

                final Integer childScore = -this.negamax(kopplung, copiedState, depth - 1, -beta, -modAlpha);
                if (childScore > score) {

                    score = childScore - depth;
                }
                modAlpha = Math.max(modAlpha, score);
                if (modAlpha >= beta) {

                    break;
                }

            }

            return score;
        }

        throw new GameException("Something went wrong with  Negamax");

    }

}