backgammon/board.py

from cup import Cup
import numpy as np

class Board:

    # Remember to handle pushing other pieces to home
    # 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 = [["O",2],[" ",0],[" ",0],[" ",0],[" ",0],["X",5],[" ",0],["X",3],[" ",0],[" ",0],[" ",0],["O",5],["X",5],[" ",0],[" ",0],[" ",0],["O",3],[" ",0],["O",5],[" ",0],[" ",0],[" ",0],[" ",0],["X",2], ["Jail",0], ["Jail",0]]
        

    def get_state(self):
        return self.state

    def switch(self,cur):
        return "X" if cur == "O" else "O"


    # 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_ = jail and if so, allow some extra stuff!
    
    def check_move(self, move, sym, roll):
        from_ = int(move[0])
        to = int(move[1])
        if from_ == 24:
            from_ = 0
            roll -= 1
        elif from_ == 25:
            from_ = 23
            roll -= 1
        if (from_ < 0 or from_ > 23) or (to < 0 or to > 23):
            return False
        elif (abs(from_ - to) != roll):
            return False
        elif ((self.state[to][0] == sym or self.state[to][0] == " ") or (self.state[to][0] == self.switch(sym) and self.state[to][1] == 1)) and self.state[from_][0] == sym:
            return True



    def find_pieces_for_player(self,sym):
        idxs = []
        for idx, pip in enumerate(self.state):
            if pip[0] == sym:
                idxs.append(idx)
        return idxs
    
    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 = []
        if sym == "O":
            for index in idxs_with_thing:
                from_ = index
                to = index+roll
                if self.check_move([from_,to], sym, roll):
                    legal_moves.append([from_,to])
        else:
            for index in idxs_with_thing:
                from_ = index
                to = index-roll
                if self.check_move([from_,to], sym, roll):
                    legal_moves.append([from_,to])
        return legal_moves
    
    def to_s(self):
        return """
        ------------------------------------------
        | {22}| {20}| {18}| {16}| {14}| {12}|{48}| {10}| {8}| {6}| {4}| {2}| {0}|
        | {23}| {21}| {19}| {17}| {15}| {13}|  {49} | {11}| {9}| {7}| {5}| {3}| {1}|
        |--|--|--|--|--|--|----|--|--|--|--|--|--|
        | {24}| {26}| {28}| {30}| {32}| {34}|{50}| {36}| {38}| {40}| {42}| {44}| {46}|
        | {25}| {27}| {29}| {31}| {33}| {35}|  {51} | {37}| {39}| {41}| {43}| {45}| {47}|
        ------------------------------------------
        """.format(*np.array(self.state).flatten())

    def move_to_jail(self,sym):
        if sym == "O":
            self.state[24][1] += 1
            self.state[24][0] = "Jail"
        else:
            self.state[25][1] += 1
            self.state[25][0] = "Jail"
    
    def move_thing(self, cur_sym, from_, to):

        self.state[from_][1] -= 1
            
        if self.state[from_][1] == 0:
            self.state[from_][0] = " "

        if self.state[to][0] == self.switch(cur_sym):
            self.move_to_jail(self.switch(cur_sym))
            self.state[to][1] = 0
                
        self.state[to][0] = cur_sym
        self.state[to][1] += 1