checkers.py

from copy import deepcopy
import time
import math

ansi_black = "\u001b[30m"
ansi_red = "\u001b[31m"
ansi_green = "\u001b[32m"
ansi_yellow = "\u001b[33m"
ansi_blue = "\u001b[34m"
ansi_magenta = "\u001b[35m"
ansi_cyan = "\u001b[36m"
ansi_white = "\u001b[37m"
ansi_reset = "\u001b[0m"


class Node:
    def __init__(self, board, move=None, parent=None, value=None):
        self.board = board
        self.value = value
        self.move = move
        self.parent = parent

    def get_children(self, minimizing_player, mandatory_jumping):
        current_state = deepcopy(self.board)
        available_moves = []
        children_states = []
        big_letter = ""
        queen_row = 0
        if minimizing_player is True:
            available_moves = Checkers.find_available_moves(current_state, mandatory_jumping)
            big_letter = "C"
            queen_row = 7
        else:
            available_moves = Checkers.find_player_available_moves(current_state, mandatory_jumping)
            big_letter = "B"
            queen_row = 0
        for i in range(len(available_moves)):
            old_i = available_moves[i][0]
            old_j = available_moves[i][1]
            new_i = available_moves[i][2]
            new_j = available_moves[i][3]
            state = deepcopy(current_state)
            Checkers.make_a_move(state, old_i, old_j, new_i, new_j, big_letter, queen_row)
            children_states.append(Node(state, [old_i, old_j, new_i, new_j]))
        return children_states

    def set_value(self, value):
        self.value = value

    def get_value(self):
        return self.value

    def get_board(self):
        return self.board

    def get_parent(self):
        return self.parent

    def set_parent(self, parent):
        self.parent = parent


class Checkers:

    def __init__(self):
        self.matrix = [[], [], [], [], [], [], [], []]
        self.player_turn = True
        self.computer_pieces = 12
        self.player_pieces = 12
        self.available_moves = []
        self.mandatory_jumping = False

        for row in self.matrix:
            for i in range(8):
                row.append("---")
        self.position_computer()
        self.position_player()

    def position_computer(self):
        for i in range(3):
            for j in range(8):
                if (i + j) % 2 == 1:
                    self.matrix[i][j] = ("c" + str(i) + str(j))

    def position_player(self):
        for i in range(5, 8, 1):
            for j in range(8):
                if (i + j) % 2 == 1:
                    self.matrix[i][j] = ("b" + str(i) + str(j))

    def print_matrix(self):
        i = 0
        print()
        for row in self.matrix:
            print(i, end="  |")
            i += 1
            for elem in row:
                print(elem, end=" ")
            print()
        print()
        for j in range(8):
            if j == 0:
                j = "     0"
            print(j, end="   ")
        print("\n")

    def get_player_input(self):
        available_moves = Checkers.find_player_available_moves(self.matrix, self.mandatory_jumping)
        if len(available_moves) == 0:
            if self.computer_pieces > self.player_pieces:
                print(
                    ansi_red + "You have no moves left, and you have fewer pieces than the computer.YOU LOSE!" + ansi_reset)
                exit()
            else:
                print(ansi_yellow + "You have no available moves.\nGAME ENDED!" + ansi_reset)
                exit()
        self.player_pieces = 0
        self.computer_pieces = 0
        while True:

            coord1 = input("Which piece[i,j]: ")
            if coord1 == "":
                print(ansi_cyan + "Game ended!" + ansi_reset)
                exit()
            elif coord1 == "s":
                print(ansi_cyan + "You surrendered.\nCoward." + ansi_reset)
                exit()
            coord2 = input("Where to[i,j]:")
            if coord2 == "":
                print(ansi_cyan + "Game ended!" + ansi_reset)
                exit()
            elif coord2 == "s":
                print(ansi_cyan + "You surrendered.\nCoward." + ansi_reset)
                exit()
            old = coord1.split(",")
            new = coord2.split(",")

            if len(old) != 2 or len(new) != 2:
                print(ansi_red + "Illegal input" + ansi_reset)
            else:
                old_i = old[0]
                old_j = old[1]
                new_i = new[0]
                new_j = new[1]
                if not old_i.isdigit() or not old_j.isdigit() or not new_i.isdigit() or not new_j.isdigit():
                    print(ansi_red + "Illegal input" + ansi_reset)
                else:
                    move = [int(old_i), int(old_j), int(new_i), int(new_j)]
                    if move not in available_moves:
                        print(ansi_red + "Illegal move!" + ansi_reset)
                    else:
                        Checkers.make_a_move(self.matrix, int(old_i), int(old_j), int(new_i), int(new_j), "B", 0)
                        for m in range(8):
                            for n in range(8):
                                if self.matrix[m][n][0] == "c" or self.matrix[m][n][0] == "C":
                                    self.computer_pieces += 1
                                elif self.matrix[m][n][0] == "b" or self.matrix[m][n][0] == "B":
                                    self.player_pieces += 1
                        break

    @staticmethod
    def find_available_moves(board, mandatory_jumping):
        available_moves = []
        available_jumps = []
        for m in range(8):
            for n in range(8):
                if board[m][n][0] == "c":
                    if Checkers.check_moves(board, m, n, m + 1, n + 1):
                        available_moves.append([m, n, m + 1, n + 1])
                    if Checkers.check_moves(board, m, n, m + 1, n - 1):
                        available_moves.append([m, n, m + 1, n - 1])
                    if Checkers.check_jumps(board, m, n, m + 1, n - 1, m + 2, n - 2):
                        available_jumps.append([m, n, m + 2, n - 2])
                    if Checkers.check_jumps(board, m, n, m + 1, n + 1, m + 2, n + 2):
                        available_jumps.append([m, n, m + 2, n + 2])
                elif board[m][n][0] == "C":
                    if Checkers.check_moves(board, m, n, m + 1, n + 1):
                        available_moves.append([m, n, m + 1, n + 1])
                    if Checkers.check_moves(board, m, n, m + 1, n - 1):
                        available_moves.append([m, n, m + 1, n - 1])
                    if Checkers.check_moves(board, m, n, m - 1, n - 1):
                        available_moves.append([m, n, m - 1, n - 1])
                    if Checkers.check_moves(board, m, n, m - 1, n + 1):
                        available_moves.append([m, n, m - 1, n + 1])
                    if Checkers.check_jumps(board, m, n, m + 1, n - 1, m + 2, n - 2):
                        available_jumps.append([m, n, m + 2, n - 2])
                    if Checkers.check_jumps(board, m, n, m - 1, n - 1, m - 2, n - 2):
                        available_jumps.append([m, n, m - 2, n - 2])
                    if Checkers.check_jumps(board, m, n, m - 1, n + 1, m - 2, n + 2):
                        available_jumps.append([m, n, m - 2, n + 2])
                    if Checkers.check_jumps(board, m, n, m + 1, n + 1, m + 2, n + 2):
                        available_jumps.append([m, n, m + 2, n + 2])
        if mandatory_jumping is False:
            available_jumps.extend(available_moves)
            return available_jumps
        elif mandatory_jumping is True:
            if len(available_jumps) == 0:
                return available_moves
            else:
                return available_jumps

    @staticmethod
    def check_jumps(board, old_i, old_j, via_i, via_j, new_i, new_j):
        if new_i > 7 or new_i < 0:
            return False
        if new_j > 7 or new_j < 0:
            return False
        if board[via_i][via_j] == "---":
            return False
        if board[via_i][via_j][0] == "C" or board[via_i][via_j][0] == "c":
            return False
        if board[new_i][new_j] != "---":
            return False
        if board[old_i][old_j] == "---":
            return False
        if board[old_i][old_j][0] == "b" or board[old_i][old_j][0] == "B":
            return False
        return True

    @staticmethod
    def check_moves(board, old_i, old_j, new_i, new_j):

        if new_i > 7 or new_i < 0:
            return False
        if new_j > 7 or new_j < 0:
            return False
        if board[old_i][old_j] == "---":
            return False
        if board[new_i][new_j] != "---":
            return False
        if board[old_i][old_j][0] == "b" or board[old_i][old_j][0] == "B":
            return False
        if board[new_i][new_j] == "---":
            return True

    @staticmethod
    def calculate_heuristics(board):
        result = 0
        mine = 0
        opp = 0
        for i in range(8):
            for j in range(8):
                if board[i][j][0] == "c" or board[i][j][0] == "C":
                    mine += 1

                    if board[i][j][0] == "c":
                        result += 5
                    if board[i][j][0] == "C":
                        result += 10
                    if i == 0 or j == 0 or i == 7 or j == 7:
                        result += 7
                    if i + 1 > 7 or j - 1 < 0 or i - 1 < 0 or j + 1 > 7:
                        continue
                    if (board[i + 1][j - 1][0] == "b" or board[i + 1][j - 1][0] == "B") and board[i - 1][
                        j + 1] == "---":
                        result -= 3
                    if (board[i + 1][j + 1][0] == "b" or board[i + 1][j + 1] == "B") and board[i - 1][j - 1] == "---":
                        result -= 3
                    if board[i - 1][j - 1][0] == "B" and board[i + 1][j + 1] == "---":
                        result -= 3

                    if board[i - 1][j + 1][0] == "B" and board[i + 1][j - 1] == "---":
                        result -= 3
                    if i + 2 > 7 or i - 2 < 0:
                        continue
                    if (board[i + 1][j - 1][0] == "B" or board[i + 1][j - 1][0] == "b") and board[i + 2][
                        j - 2] == "---":
                        result += 6
                    if i + 2 > 7 or j + 2 > 7:
                        continue
                    if (board[i + 1][j + 1][0] == "B" or board[i + 1][j + 1][0] == "b") and board[i + 2][
                        j + 2] == "---":
                        result += 6

                elif board[i][j][0] == "b" or board[i][j][0] == "B":
                    opp += 1

        return result + (mine - opp) * 1000

    @staticmethod
    def find_player_available_moves(board, mandatory_jumping):
        available_moves = []
        available_jumps = []
        for m in range(8):
            for n in range(8):
                if board[m][n][0] == "b":
                    if Checkers.check_player_moves(board, m, n, m - 1, n - 1):
                        available_moves.append([m, n, m - 1, n - 1])
                    if Checkers.check_player_moves(board, m, n, m - 1, n + 1):
                        available_moves.append([m, n, m - 1, n + 1])
                    if Checkers.check_player_jumps(board, m, n, m - 1, n - 1, m - 2, n - 2):
                        available_jumps.append([m, n, m - 2, n - 2])
                    if Checkers.check_player_jumps(board, m, n, m - 1, n + 1, m - 2, n + 2):
                        available_jumps.append([m, n, m - 2, n + 2])
                elif board[m][n][0] == "B":
                    if Checkers.check_player_moves(board, m, n, m - 1, n - 1):
                        available_moves.append([m, n, m - 1, n - 1])
                    if Checkers.check_player_moves(board, m, n, m - 1, n + 1):
                        available_moves.append([m, n, m - 1, n + 1])
                    if Checkers.check_player_jumps(board, m, n, m - 1, n - 1, m - 2, n - 2):
                        available_jumps.append([m, n, m - 2, n - 2])
                    if Checkers.check_player_jumps(board, m, n, m - 1, n + 1, m - 2, n + 2):
                        available_jumps.append([m, n, m - 2, n + 2])
                    if Checkers.check_player_moves(board, m, n, m + 1, n - 1):
                        available_moves.append([m, n, m + 1, n - 1])
                    if Checkers.check_player_jumps(board, m, n, m + 1, n - 1, m + 2, n - 2):
                        available_jumps.append([m, n, m + 2, n - 2])
                    if Checkers.check_player_moves(board, m, n, m + 1, n + 1):
                        available_moves.append([m, n, m + 1, n + 1])
                    if Checkers.check_player_jumps(board, m, n, m + 1, n + 1, m + 2, n + 2):
                        available_jumps.append([m, n, m + 2, n + 2])
        if mandatory_jumping is False:
            available_jumps.extend(available_moves)
            return available_jumps
        elif mandatory_jumping is True:
            if len(available_jumps) == 0:
                return available_moves
            else:
                return available_jumps

    @staticmethod
    def check_player_moves(board, old_i, old_j, new_i, new_j):
        if new_i > 7 or new_i < 0:
            return False
        if new_j > 7 or new_j < 0:
            return False
        if board[old_i][old_j] == "---":
            return False
        if board[new_i][new_j] != "---":
            return False
        if board[old_i][old_j][0] == "c" or board[old_i][old_j][0] == "C":
            return False
        if board[new_i][new_j] == "---":
            return True

    @staticmethod
    def check_player_jumps(board, old_i, old_j, via_i, via_j, new_i, new_j):
        if new_i > 7 or new_i < 0:
            return False
        if new_j > 7 or new_j < 0:
            return False
        if board[via_i][via_j] == "---":
            return False
        if board[via_i][via_j][0] == "B" or board[via_i][via_j][0] == "b":
            return False
        if board[new_i][new_j] != "---":
            return False
        if board[old_i][old_j] == "---":
            return False
        if board[old_i][old_j][0] == "c" or board[old_i][old_j][0] == "C":
            return False
        return True

    def evaluate_states(self):
        t1 = time.time()
        current_state = Node(deepcopy(self.matrix))

        first_computer_moves = current_state.get_children(True, self.mandatory_jumping)
        if len(first_computer_moves) == 0:
            if self.player_pieces > self.computer_pieces:
                print(
                    ansi_yellow + "Computer has no available moves left, and you have more pieces left.\nYOU WIN!" + ansi_reset)
                exit()
            else:
                print(ansi_yellow + "Computer has no available moves left.\nGAME ENDED!" + ansi_reset)
                exit()
        dict = {}
        for i in range(len(first_computer_moves)):
            child = first_computer_moves[i]
            value = Checkers.minimax(child.get_board(), 4, -math.inf, math.inf, False, self.mandatory_jumping)
            dict[value] = child
        if len(dict.keys()) == 0:
            print(ansi_green + "Computer has cornered itself.\nYOU WIN!" + ansi_reset)
            exit()
        new_board = dict[max(dict)].get_board()
        move = dict[max(dict)].move
        self.matrix = new_board
        t2 = time.time()
        diff = t2 - t1
        print("Computer has moved (" + str(move[0]) + "," + str(move[1]) + ") to (" + str(move[2]) + "," + str(
            move[3]) + ").")
        print("It took him " + str(diff) + " seconds.")

    @staticmethod
    def minimax(board, depth, alpha, beta, maximizing_player, mandatory_jumping):
        if depth == 0:
            return Checkers.calculate_heuristics(board)
        current_state = Node(deepcopy(board))
        if maximizing_player is True:
            max_eval = -math.inf
            for child in current_state.get_children(True, mandatory_jumping):
                ev = Checkers.minimax(child.get_board(), depth - 1, alpha, beta, False, mandatory_jumping)
                max_eval = max(max_eval, ev)
                alpha = max(alpha, ev)
                if beta <= alpha:
                    break
            current_state.set_value(max_eval)
            return max_eval
        else:
            min_eval = math.inf
            for child in current_state.get_children(False, mandatory_jumping):
                ev = Checkers.minimax(child.get_board(), depth - 1, alpha, beta, True, mandatory_jumping)
                min_eval = min(min_eval, ev)
                beta = min(beta, ev)
                if beta <= alpha:
                    break
            current_state.set_value(min_eval)
            return min_eval

    @staticmethod
    def make_a_move(board, old_i, old_j, new_i, new_j, big_letter, queen_row):
        letter = board[old_i][old_j][0]
        i_difference = old_i - new_i
        j_difference = old_j - new_j
        if i_difference == -2 and j_difference == 2:
            board[old_i + 1][old_j - 1] = "---"

        elif i_difference == 2 and j_difference == 2:
            board[old_i - 1][old_j - 1] = "---"

        elif i_difference == 2 and j_difference == -2:
            board[old_i - 1][old_j + 1] = "---"

        elif i_difference == -2 and j_difference == -2:
            board[old_i + 1][old_j + 1] = "---"

        if new_i == queen_row:
            letter = big_letter
        board[old_i][old_j] = "---"
        board[new_i][new_j] = letter + str(new_i) + str(new_j)

    def play(self):
        print(ansi_cyan + "##### WELCOME TO CHECKERS ####" + ansi_reset)
        print("\nSome basic rules:")
        print("1.You enter the coordinates in the form i,j.")
        print("2.You can quit the game at any time by pressing enter.")
        print("3.You can surrender at any time by pressing 's'.")
        print("Now that you've familiarized yourself with the rules, enjoy!")
        while True:
            answer = input("\nFirst, we need to know, is jumping mandatory?[Y/n]: ")
            if answer == "Y" or answer == "y":
                self.mandatory_jumping = True
                break
            elif answer == "N" or answer == "n":
                self.mandatory_jumping = False
                break
            elif answer == "":
                print(ansi_cyan + "Game ended!" + ansi_reset)
                exit()
            elif answer == "s":
                print(ansi_cyan + "You've surrendered before the game even started.\nPathetic." + ansi_reset)
                exit()
            else:
                print(ansi_red + "Illegal input!" + ansi_reset)
        while True:
            self.print_matrix()
            if self.player_turn is True:
                print(ansi_cyan + "\nPlayer's turn." + ansi_reset)
                self.get_player_input()
            else:
                print(ansi_cyan + "Computer's turn." + ansi_reset)
                print("Thinking...")
                self.evaluate_states()
            if self.player_pieces == 0:
                self.print_matrix()
                print(ansi_red + "You have no pieces left.\nYOU LOSE!" + ansi_reset)
                exit()
            elif self.computer_pieces == 0:
                self.print_matrix()
                print(ansi_green + "Computer has no pieces left.\nYOU WIN!" + ansi_reset)
                exit()
            elif self.computer_pieces - self.player_pieces == 7:
                wish = input("You have 7 pieces fewer than your opponent.Do you want to surrender?")
                if wish == "" or wish == "yes":
                    print(ansi_cyan + "Coward." + ansi_reset)
                    exit()
            self.player_turn = not self.player_turn


if __name__ == '__main__':
    checkers = Checkers()
    checkers.play()