masters-dissertation/minimax/minimaxAlgo.py

import random
from math import inf

from utilities.constants import GREEN, WHITE
from utilities.gameManager import GameManager


class MiniMax:

    def AI(self, depth: int, maxPlayer: int, gameManager: GameManager) -> tuple:
        """
        The minimax algorithm
        :param depth: How deep the algorithm should go
        :param maxPlayer: The current player
        :param gameManager: The game manager
        :return: the best evaluation and board
        """
        if depth == 0 or gameManager.board.winner() is not None:
            return gameManager.board.scoreOfTheBoard(), gameManager.board

        if type(maxPlayer) == int:
            maxEval = -inf
            bestMove = None
            for move in gameManager.board.getAllMoves(maxPlayer):
                evaluation = self.AI(depth - 1, False, gameManager)[0]
                maxEval = max(maxEval, evaluation)
                if maxEval > evaluation:
                    bestMove = move
                if maxEval == evaluation:
                    # bestMove = move
                    bestMove = bestMove if random.choice([True, False]) else move
            return maxEval, bestMove
        else:
            minEval = inf
            bestMove = None
            colour = WHITE if gameManager.turn == GREEN else GREEN
            for move in gameManager.board.getAllMoves(colour):
                evaluation = self.AI(depth - 1, True, gameManager)[0]
                minEval = min(minEval, evaluation)
                if minEval < evaluation:
                    bestMove = move
                if minEval == evaluation:
                    # bestMove = move
                    bestMove = bestMove if random.choice([True, False]) else move

            return minEval, bestMove