# Copyright 2007 Google Inc.
#  Licensed to PSF under a Contributor Agreement.

"""A fast, lightweight IPv4/IPv6 manipulation library in Python.

This library is used to create/poke/manipulate IPv4 and IPv6 addresses
and networks.

"""

__version__ = '1.0'


import functools

IPV4LENGTH = 32
IPV6LENGTH = 128

class AddressValueError(ValueError):
    """A Value Error related to the address."""


class NetmaskValueError(ValueError):
    """A Value Error related to the netmask."""


def ip_address(address):
    """Take an IP string/int and return an object of the correct type.

    Args:
        address: A string or integer, the IP address.  Either IPv4 or
          IPv6 addresses may be supplied; integers less than 2**32 will
          be considered to be IPv4 by default.

    Returns:
        An IPv4Address or IPv6Address object.

    Raises:
        ValueError: if the *address* passed isn't either a v4 or a v6
          address

    """
    try:
        return IPv4Address(address)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Address(address)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError('%r does not appear to be an IPv4 or IPv6 address' %
                     address)


def ip_network(address, strict=True):
    """Take an IP string/int and return an object of the correct type.

    Args:
        address: A string or integer, the IP network.  Either IPv4 or
          IPv6 networks may be supplied; integers less than 2**32 will
          be considered to be IPv4 by default.

    Returns:
        An IPv4Network or IPv6Network object.

    Raises:
        ValueError: if the string passed isn't either a v4 or a v6
          address. Or if the network has host bits set.

    """
    try:
        return IPv4Network(address, strict)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Network(address, strict)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError('%r does not appear to be an IPv4 or IPv6 network' %
                     address)


def ip_interface(address):
    """Take an IP string/int and return an object of the correct type.

    Args:
        address: A string or integer, the IP address.  Either IPv4 or
          IPv6 addresses may be supplied; integers less than 2**32 will
          be considered to be IPv4 by default.

    Returns:
        An IPv4Interface or IPv6Interface object.

    Raises:
        ValueError: if the string passed isn't either a v4 or a v6
          address.

    Notes:
        The IPv?Interface classes describe an Address on a particular
        Network, so they're basically a combination of both the Address
        and Network classes.

    """
    try:
        return IPv4Interface(address)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Interface(address)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError('%r does not appear to be an IPv4 or IPv6 interface' %
                     address)


def v4_int_to_packed(address):
    """Represent an address as 4 packed bytes in network (big-endian) order.

    Args:
        address: An integer representation of an IPv4 IP address.

    Returns:
        The integer address packed as 4 bytes in network (big-endian) order.

    Raises:
        ValueError: If the integer is negative or too large to be an
          IPv4 IP address.

    """
    try:
        return address.to_bytes(4, 'big')
    except OverflowError:
        raise ValueError("Address negative or too large for IPv4")


def v6_int_to_packed(address):
    """Represent an address as 16 packed bytes in network (big-endian) order.

    Args:
        address: An integer representation of an IPv6 IP address.

    Returns:
        The integer address packed as 16 bytes in network (big-endian) order.

    """
    try:
        return address.to_bytes(16, 'big')
    except OverflowError:
        raise ValueError("Address negative or too large for IPv6")


def _split_optional_netmask(address):
    """Helper to split the netmask and raise AddressValueError if needed"""
    addr = str(address).split('/')
    if len(addr) > 2:
        raise AddressValueError("Only one '/' permitted in %r" % address)
    return addr


def _find_address_range(addresses):
    """Find a sequence of sorted deduplicated IPv#Address.

    Args:
        addresses: a list of IPv#Address objects.

    Yields:
        A tuple containing the first and last IP addresses in the sequence.

    """
    it = iter(addresses)
    first = last = next(it)
    for ip in it:
        if ip._ip != last._ip + 1:
            yield first, last
            first = ip
        last = ip
    yield first, last


def _count_righthand_zero_bits(number, bits):
    """Count the number of zero bits on the right hand side.

    Args:
        number: an integer.
        bits: maximum number of bits to count.

    Returns:
        The number of zero bits on the right hand side of the number.

    """
    if number == 0:
        return bits
    return min(bits, (~number & (number-1)).bit_length())


def summarize_address_range(first, last):
    """Summarize a network range given the first and last IP addresses.

    Example:
        >>> list(summarize_address_range(IPv4Address('192.0.2.0'),
        ...                              IPv4Address('192.0.2.130')))
        ...                                #doctest: +NORMALIZE_WHITESPACE
        [IPv4Network('192.0.2.0/25'), IPv4Network('192.0.2.128/31'),
         IPv4Network('192.0.2.130/32')]

    Args:
        first: the first IPv4Address or IPv6Address in the range.
        last: the last IPv4Address or IPv6Address in the range.

    Returns:
        An iterator of the summarized IPv(4|6) network objects.

    Raise:
        TypeError:
            If the first and last objects are not IP addresses.
            If the first and last objects are not the same version.
        ValueError:
            If the last object is not greater than the first.
            If the version of the first address is not 4 or 6.

    """
    if (not (isinstance(first, _BaseAddress) and
             isinstance(last, _BaseAddress))):
        raise TypeError('first and last must be IP addresses, not networks')
    if first.version != last.version:
        raise TypeError("%s and %s are not of the same version" % (
                         first, last))
    if first > last:
        raise ValueError('last IP address must be greater than first')

    if first.version == 4:
        ip = IPv4Network
    elif first.version == 6:
        ip = IPv6Network
    else:
        raise ValueError('unknown IP version')

    ip_bits = first._max_prefixlen
    first_int = first._ip
    last_int = last._ip
    while first_int <= last_int:
        nbits = min(_count_righthand_zero_bits(first_int, ip_bits),
                    (last_int - first_int + 1).bit_length() - 1)
        net = ip((first_int, ip_bits - nbits))
        yield net
        first_int += 1 << nbits
        if first_int - 1 == ip._ALL_ONES:
            break


def _collapse_addresses_internal(addresses):
    """Loops through the addresses, collapsing concurrent netblocks.

    Example:

        ip1 = IPv4Network('192.0.2.0/26')
        ip2 = IPv4Network('192.0.2.64/26')
        ip3 = IPv4Network('192.0.2.128/26')
        ip4 = IPv4Network('192.0.2.192/26')

        _collapse_addresses_internal([ip1, ip2, ip3, ip4]) ->
          [IPv4Network('192.0.2.0/24')]

        This shouldn't be called directly; it is called via
          collapse_addresses([]).

    Args:
        addresses: A list of IPv4Network's or IPv6Network's

    Returns:
        A list of IPv4Network's or IPv6Network's depending on what we were
        passed.

    """
    # First merge
    to_merge = list(addresses)
    subnets = {}
    while to_merge:
        net = to_merge.pop()
        supernet = net.supernet()
        existing = subnets.get(supernet)
        if existing is None:
            subnets[supernet] = net
        elif existing != net:
            # Merge consecutive subnets
            del subnets[supernet]
            to_merge.append(supernet)
    # Then iterate over resulting networks, skipping subsumed subnets
    last = None
    for net in sorted(subnets.values()):
        if last is not None:
            # Since they are sorted, last.network_address <= net.network_address
            # is a given.
            if last.broadcast_address >= net.broadcast_address:
                continue
        yield net
        last = net


def collapse_addresses(addresses):
    """Collapse a list of IP objects.

    Example:
        collapse_addresses([IPv4Network('192.0.2.0/25'),
                            IPv4Network('192.0.2.128/25')]) ->
                           [IPv4Network('192.0.2.0/24')]

    Args:
        addresses: An iterator of IPv4Network or IPv6Network objects.

    Returns:
        An iterator of the collapsed IPv(4|6)Network objects.

    Raises:
        TypeError: If passed a list of mixed version objects.

    """
    addrs = []
    ips = []
    nets = []

    # split IP addresses and networks
    for ip in addresses:
        if isinstance(ip, _BaseAddress):
            if ips and ips[-1]._version != ip._version:
                raise TypeError("%s and %s are not of the same version" % (
                                 ip, ips[-1]))
            ips.append(ip)
        elif ip._prefixlen == ip._max_prefixlen:
            if ips and ips[-1]._version != ip._version:
                raise TypeError("%s and %s are not of the same version" % (
                                 ip, ips[-1]))
            try:
                ips.append(ip.ip)
            except AttributeError:
                ips.append(ip.network_address)
        else:
            if nets and nets[-1]._version != ip._version:
                raise TypeError("%s and %s are not of the same version" % (