def num_neighbours(lines: [], line_index: int, pos_index: int, num_lines: int, line_length: int) -> int:
    '''Check surrounding and current row neighbours of a given position.
    Does not operate on 2d coords directly, but on index and current versus prev/next lines.
    '''
    total = 0

    for ii in range(max(0, line_index - 1), min(num_lines, line_index + 2)):
        for jj in range(max(0, pos_index - 1), min(line_length, pos_index + 2)):
            if ii == line_index and jj == pos_index:
                continue

            if lines[ii][jj] == '@':
                total += 1

    return total

def process_line(lines: []) -> int:
    '''Iterate through all lines in the map and determine which can be removed this time around'''
    total = 0

    for line_index, line in enumerate(lines):
        for index, char in enumerate(line):
            if char == '@':
                total_neighbours = num_neighbours(lines, line_index, index, len(lines), len(line))

                if total_neighbours < 4:
                    total += 1

    return total


def find_all_accessible_rolls(lines: []) -> int:
    '''Recursively iterate through removing paper rolls and see how many are opened up for removal after each pass until none can be removed'''
    total = 0

    # Copy the map to note which have been removed without affecting the current checks
    lines_copy = lines

    for line_index, line in enumerate(lines):
        for index, char in enumerate(line):
            if char == '@':
                total_neighbours = 0

                for ii in range(max(0, line_index - 1), min(len(lines), line_index + 2)):
                    for jj in range(max(0, index - 1), min(len(line), index + 2)):
                        if ii == line_index and jj == index:
                            continue

                        if lines[ii][jj] == '@':
                            total_neighbours += 1

                if total_neighbours < 4:
                    total += 1
                    temp_line = list(lines_copy[line_index])
                    temp_line[index] = '.'
                    lines_copy[line_index] = ''.join(temp_line)

    if total != 0:
        return total + find_all_accessible_rolls(lines_copy)

    return total


def main():
    '''Entrypoint'''
    with open('input.txt', encoding='utf-8') as fh:
        all_lines = fh.readlines()
        part1_total = process_line(all_lines)

        print(f'Part 1: {part1_total}')

        part2_total = find_all_accessible_rolls(all_lines)

        print(f'Part 2: {part2_total}')


if __name__ == "__main__":
    main()