package checkers;

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;

public class AlphaBeta extends MinMaxPlayer {

    protected AlphaBeta(String name, int maxDepth) {
        super(name, maxDepth);
    }


      @Override
      public String getMove(Board game, LinkedList<String> allMoves) {
        color = game.getCurrentPlayer();
        float max = Float.NEGATIVE_INFINITY;
        String best = null;
        for (String move : allMoves) {
          Board test = new Board(game);
          test.playMove(move);
          NB_EVAL++;
          float tmp = evalMin(test, MAX_DEPTH, 0);
          if (tmp > max) {
            max = tmp;
            best = move;
          }
        } // for move in allMoves
        return best;
      }

      private float evalMin(Board board, int depthLeft, int minimum) {
        float min = Float.POSITIVE_INFINITY;
        LinkedList<String> allMoves = board.getAllMoves();

        if (allMoves.isEmpty() || depthLeft==0) {
          int score = board.getBalance();
          if (color == Piece.White)
            return score;
          else
            return -score;
        }
        for (String move : allMoves) {
          Board test = new Board(board);
          test.playMove(move);
          NB_EVAL++;
          float tmp = evalMin(test, depthLeft-1, minimum);
          if(tmp< minimum){
              return tmp; //Si on trouve une valeur plus petite que celle deja évalué, on la retourne et on ne regarde pas les noeuds frères
          }
          if (tmp > min) {
            min = tmp;
          }
        } // for move in allMoves
        return min;
      }

      private float evalMax(Board board, int depthLeft, int maximum) {
        float max = Float.NEGATIVE_INFINITY;
        LinkedList<String> allMoves = board.getAllMoves();
        if (allMoves.isEmpty() || depthLeft==0) {
          int score = board.getBalance();
          if (color == Piece.White)
            return score;
          else
            return -score;
        }
        for (String move : allMoves) {
          Board test = new Board(board);
          test.playMove(move);
          NB_EVAL++;
          float tmp = evalMin(test, depthLeft-1, maximum);
          if(tmp > maximum){
              return tmp;  //Si on trouve une valeur plus grande que celle deja évalué, on la retourne et on ne regarde pas les noeuds frères
          }
          if (tmp < max) {
            max = tmp;
          }
        } // for move in allMoves
        return max;
      }

      @Override
      public int getNbEvals() {
        return NB_EVAL;
      }
}