backgammon/board.py

from cup import Cup
import numpy as np

class Board:

    # TODO: Remember to handle pushing other pieces to home
    # TODO: Also remember that a player can't move backwards and the one
    #  player goes from 1-47 while the other goes from 47-1

    def __init__(self):
        self.cup = Cup()
        self.state = [ 0,
                       2, 0, 0, 0, 0, -5,
                       0, -3, 0, 0, 0, 5,
                       -5, 0, 0, 0, 3, 0,
                       5, 0, 0, 0, 0, -2,
                       0, 0, 0]
        

    def get_state(self):
        return self.state

    def switch(self,cur):
        return -1 if cur == 1 else 1


    # Remember to handle edge case when we're on the last moves and you may go
    # from position 22 -> 24 on a 6, if you have no pieces behind 22. Simply
    # check if any are behind if you're circle or if any are higher if you are
    # X, then it can be allowed.

    # Also, the check_move will also fail when you're attempting to leave a
    # jail. A fix of this is of course to check if the from_idx = jail and if so,
    # allow some extra stuff!
    
    def check_move(self, move, sym, roll):
        from_idx = int(move[0])
        to_idx = int(move[1])
        if from_idx == 26:
            from_idx = 1
            roll -= 1
        elif from_idx == 27:
            from_idx = 24
            roll -= 1
        if (from_idx < 1 or from_idx > 24) or (to_idx < 1 or to_idx > 24):
            return False
        elif (abs(from_idx - to_idx) != roll):
            return False
        elif ((self.state[to_idx] * sym >= 0 or self.state[to_idx] == 0) or (self.state[to_idx] * self.switch(sym) == 1)) and self.state[from_idx] * sym >= 1:
            return True

    def find_pieces_for_player(self,sym):
        idxs = []
        for idx, pip in enumerate(self.state):
            if pip * sym >= 1:
                idxs.append(idx)
        return idxs

    def is_winner(self,sym):
        for i in range(1,25):
            if sym * self.state[i] > 0:
                return False
        return True
        
    
    def find_legal_moves(self,sym,roll):
        # Find all pips with things on them belonging to the player
        # Iterate through each index and check if it's a possible move given the roll
        # If player is O, then check for idx + roll
        # If player is X, then check for idx - roll
        
        # Rewrite this, it's shit.
        idxs_with_thing = self.find_pieces_for_player(sym)
        legal_moves = []

        for index in idxs_with_thing:
            from_idx = index
            to_idx = index+(roll*sym)
            if self.check_move([from_idx,to_idx], sym, roll):
                legal_moves.append([from_idx,to_idx])

        return legal_moves
    
    def to_s(self):
        temp = []
        for x in self.state:
            if x >= 0:
                temp.append(" {}".format(x))
            else:
                temp.append("{}".format(x))

        
        return """
        ------------------------------------------------------------
        |{12}|{11}|{10}|{9}|{8}|{7}|bar  1: {26} |{6}|{5}|{4}|{3}|{2}|{1}|end -1: {0}|
        |--|--|--|--|--|--|--------|--|--|--|--|--|--|
        |{13}|{14}|{15}|{16}|{17}|{18}|bar -1: {27} |{19}|{20}|{21}|{22}|{23}|{24}|end  1: {25}|
        ------------------------------------------------------------
        """.format(*temp)

    def move_to_jail(self,sym):
        if sym == 1:
            self.state[26] += sym
        else:
            self.state[27] += sym
    
    def move_thing(self, cur_sym, from_idx, to_idx):

        self.state[from_idx] -= cur_sym
            
        if self.state[to_idx] * cur_sym <= -1:
            self.move_to_jail(self.switch(cur_sym))
            self.state[to_idx] = 0
                
        self.state[to_idx] += cur_sym