from math import cos, sin, pi
from enum import IntFlag
import numpy as np

# OUTPUT :
#
# Walkable space :
# [[ True  True  True  True  True]
#  [ True False False False  True]
#  [ True False False False  True]
#  [ True False False False  True]
#  [ True  True  True  True  True]]
#
# Corners:
# (1, 1) Wall.SOUTH|EAST
# (1, 3) Wall.NORTH|EAST
# (3, 1) Wall.WEST|SOUTH
# (3, 3) Wall.NORTH|WEST
#
# Wall space :
# [[ 0  0  0  0  0]
#  [ 0  3  7  6  0]
#  [ 0 11 15 14  0]
#  [ 0  9 13 12  0]
#  [ 0  0  0  0  0]]


class Wall(IntFlag):
    EAST = 2**0
    SOUTH = 2**1
    WEST = 2**2
    NORTH = 2**3


def fetch_wall(pos, walkable_space):
    x, y = pos
    height, width = walkable_space.shape
    if walkable_space[y, x]:
        return 0

    wall = 0
    for i in range(4):
        dx, dy = round(cos(i*pi/2)), round(sin(i*pi/2))
        if 0 <= y+dy < height and 0 <= x+dx < width:
            wall += (not walkable_space[y+dy, x+dx]) * 2**i
    return wall


def main():
    ws = np.ones((5, 5), dtype=bool)
    height, width = ws.shape
    ws[1:4, 1:4] = False

    print("Walkable space :")
    print(ws)
    print()

    positions = [(x, y) for x in range(1, 4, 2) for y in range(1, 4, 2)]
    print("Corners:")
    for pos in positions:
        print(pos, Wall(fetch_wall(pos, ws)))
    print()

    wall_space = np.zeros(ws.shape, np.int8)
    for j in range(height):
        for i in range(width):
            wall_space[j, i] = fetch_wall((i, j), ws)
    print("Wall space :")
    print(wall_space)


if __name__ == "__main__":
    main()