from .net_cidr_is_cidr import cidr_block
from .net_cidr_types import CidrInfo
from .net_ipv4_format_ipv4 import format_ipv4


def cidr_info(cidr: str) -> CidrInfo:
    """Everything a subnet calculator shows for one IPv4 block.

    Host bits in the input are dropped (192.168.1.77/24 describes
    192.168.1.0/24). A /31 is a point-to-point link with two usable addresses
    and no broadcast (RFC 3021); a /32 is one host.
    """
    block = cidr_block(cidr)
    if block is None:
        raise ValueError('"%s" is not a CIDR block' % (cidr,))
    if block.version != 4:
        raise ValueError('cidrInfo handles IPv4 blocks only, received "%s"' % (cidr,))
    prefix = block.prefix
    size = 2 ** (32 - prefix)
    network = block.bits[0] - block.bits[0] % size
    last = network + size - 1
    point_to_point = prefix >= 31
    return CidrInfo(
        cidr="%s/%d" % (format_ipv4(network), prefix),
        network=format_ipv4(network),
        prefix=prefix,
        netmask=format_ipv4(4294967296 - size),
        wildcard=format_ipv4(size - 1),
        broadcast=None if point_to_point else format_ipv4(last),
        first_host=format_ipv4(network if point_to_point else network + 1),
        last_host=format_ipv4(last if point_to_point else last - 1),
        host_count=size if point_to_point else size - 2,
        address_count=size,
    )