import copy

width = 0
height = 0


def nextSeat(x, y, grid):
    if grid[x][y] == '.':
        return '.'

    occupied = 0

    forbidden = [-1, height, width]
    xs = [a for a in [x - 1, x, x + 1] if a not in forbidden]
    ys = [a for a in [y - 1, y, y + 1] if a not in forbidden]

    for xz in xs:
        for yz in ys:
            if x is xz and y is yz:
                continue
            if grid[xz][yz] == '#':
                occupied += 1

    if grid[x][y] == 'L' and occupied == 0:
        return '#'
    elif grid[x][y] == '#' and occupied >= 4:
        return 'L'
    else:
        return grid[x][y]


def nextSeatPart2(x, y, grid):
    if grid[x][y] == '.':
        return '.'

    occupied = 0

    # go left
    i = x - 1
    while width > i >= 0:
        if grid[i][y] == '#':
            occupied += 1
            break
        if grid[i][y] == 'L':
            break
        i -= 1

    # go right
    i = x + 1
    while width > i >= 0:
        if grid[i][y] == '#':
            occupied += 1
            break
        if grid[i][y] == 'L':
            break
        i += 1

    # go up
    j = y + 1
    while height > j >= 0:
        if grid[x][j] == '#':
            occupied += 1
            break
        if grid[x][j] == 'L':
            break
        j += 1

    # go down
    j = y - 1
    while height > j >= 0:
        if grid[x][j] == '#':
            occupied += 1
            break
        if grid[x][j] == 'L':
            break
        j -= 1

    # go left/up
    i = x - 1
    j = y - 1
    while height > j >= 0 and width > i >= 0:
        if grid[i][j] == '#':
            occupied += 1
            break
        if grid[i][j] == 'L':
            break
        i -= 1
        j -= 1

    i = x - 1
    j = y + 1
    while height > j >= 0 and width > i >= 0:
        if grid[i][j] == '#':
            occupied += 1
            break
        if grid[i][j] == 'L':
            break
        i -= 1
        j += 1

    i = x + 1
    j = y + 1
    while height > j >= 0 and width > i >= 0:
        if grid[i][j] == '#':
            occupied += 1
            break
        if grid[i][j] == 'L':
            break
        i += 1
        j += 1

    i = x + 1
    j = y - 1
    while height > j >= 0 and width > i >= 0:
        if grid[i][j] == '#':
            occupied += 1
            break
        if grid[i][j] == 'L':
            break
        i += 1
        j -= 1

    if grid[x][y] == 'L' and occupied == 0:
        return '#'
    elif grid[x][y] == '#' and occupied >= 5:
        return 'L'
    else:
        return grid[x][y]


def nextRound(grid):
    next_grid = copy.deepcopy(grid)

    count = 0
    difference = False

    for x in range(0, width):
        for y in range(0, height):
            next_grid[x][y] = nextSeat(x, y, grid)
            if next_grid[x][y] == '#':
                count += 1
            if next_grid[x][y] != grid[x][y]:
                difference = True

    return next_grid, difference, count


def nextRound2(grid):
    next_grid = copy.deepcopy(grid)

    count = 0
    difference = False

    for x in range(0, width):
        for y in range(0, height):
            next_grid[x][y] = nextSeatPart2(x, y, grid)
            if next_grid[x][y] == '#':
                count += 1
            if next_grid[x][y] != grid[x][y]:
                difference = True

    return next_grid, difference, count


def part1():
    file = open("input.txt")
    lines = file.readlines()

    grid = []

    for line in lines:
        row = []
        for spot in line.strip():
            row.append(spot)
        grid.append(row)

    global width, height
    width = len(grid[0])
    height = len(grid)

    while True:
        grid, difference, count = nextRound(grid)
        if not difference:
            break

    print(f"Part 1: {count}")


def part2():
    file = open("input.txt")
    lines = file.readlines()

    grid = []

    for line in lines:
        row = []
        for spot in line.strip():
            row.append(spot)
        grid.append(row)

    global width, height
    width = len(grid[0])
    height = len(grid)

    while True:
        grid, difference, count = nextRound2(grid)
        if not difference:
            break

    print(f"Part 2: {count}")


if __name__ == "__main__":
    part1()
    part2()