import cProfile

Node = tuple[int, int]


class Cidr4MergerError(Exception):
    pass


def get_data(input_file):
    with open(input_file, "r") as file:
        data = file.read().splitlines()
    return data


def cidr4_to_node(cidr4: str) -> Node:
    ip_address, mask_len = cidr4.strip().split("/")
    a, b, c, d = list(map(int, ip_address.split(".")))
    ip = a * 256**3 + b * 256**2 + c * 256**1 + d * 256**0
    mask_len = int(mask_len)
    return ip, mask_len


def sort_nodes(nodes: list[Node]) -> list[Node]:
    return sorted(nodes)


def find_parent(a: Node, b: Node) -> Node:
    ip_a, mask_len_a = a
    ip_b, mask_len_b = b
    mask_len = min(mask_len_a, mask_len_b)
    mask = ((1 << mask_len) - 1) << (32 - mask_len)
    while ip_a & mask != ip_b & mask:
        mask_len -= 1
        mask = (mask << 1) & ((1 << 32) - 1)
    ip = ip_a & mask
    parent_node = ip, mask_len
    if parent_node == a or parent_node == b:
        raise Cidr4MergerError(
            f"Error! Trying to find common parent of network and subnet! {parent_node=}, {a=}, {b=}."
        )
    return parent_node


def calc_dip(mask_len_a: int, mask_len_b: int, mask_len_p: int) -> int:
    mask_len = mask_len_p + 1
    dip_a = 0
    while mask_len_a > mask_len:
        dip_a += 2 ** (32 - mask_len_a)
        mask_len_a -= 1
    dip_b = 0
    while mask_len_b > mask_len:
        dip_b += 2 ** (32 - mask_len_b)
        mask_len_b -= 1
    return dip_a + dip_b


def merge_two_nodes(node_a: Node, node_b: Node) -> tuple[Node, int]:
    ip_a, mask_len_a = node_a
    ip_b, mask_len_b = node_b
    parent_node = find_parent(node_a, node_b)
    _, mask_len_p = parent_node
    dip = calc_dip(mask_len_a, mask_len_b, mask_len_p)
    return parent_node, dip


def make_cidr4(ip, mask_len) -> str:
    lst = [str(ip >> (i << 3) & 0xFF) for i in reversed(range(4))]
    ip_address = ".".join(lst)
    return f"{ip_address}/{mask_len}"


def merge_nodes(nodes: list[Node], required_len: int) -> tuple[list[Node], int]:
    sum_dip = 0
    while len(nodes) > required_len:
        min_tuple = None, (None, float("inf"))
        for i, (a, b) in enumerate(zip(nodes, nodes[1:])):
            parent_node, dip = merge_two_nodes(a, b)
            if dip < min_tuple[1][1]:
                min_tuple = i, (parent_node, dip)
        idx, (parent_node, dip) = min_tuple
        nodes = nodes[:idx] + [parent_node] + nodes[idx + 2 :]
        sum_dip += dip

        # for i, (a, b) in enumerate(zip(nodes, nodes[1:])):
        #     parent_node, dip = merge_two_nodes(a, b)
        #     assert parent_node != a
        #     assert parent_node != b

    return nodes, sum_dip


def main():
    file = "cidr4.txt"
    required_len = 20

    data = get_data(file)
    nodes = list(map(cidr4_to_node, data))

    nodes = sort_nodes(nodes)
    merged_nodes, sum_dip = merge_nodes(nodes, required_len)

    cidr4s = [make_cidr4(ip, mask_len) for ip, mask_len in merged_nodes]
    print(sorted(cidr4s), sum_dip, sep="\n")


if __name__ == "__main__":
    cProfile.run("main()")