from ipaddress import IPv4Network

AS_NUMBERS = {
    #               4290xxxxxx
    'home':         4290000138,
    'htz-cloud':    4290000137,
    'ionos':        4290000002,
    'glauca':       4290207960,
}

WG_AUTOGEN_NODES = [
    # only ever append to this list. If a node vanishes, set its name to
    # `None`. You may remove nodes from the end of this, though it's not
    # recommended to do so.

    None, # fkusei-locutus never used this
    'home.router',
    'htz-cloud.wireguard',
    'icinga2',
    'daisy',
]

def get_subnet_for_connection(repo, peer_a, peer_b):
    assert peer_a in WG_AUTOGEN_NODES
    assert peer_b in WG_AUTOGEN_NODES

    pos_peer_a = WG_AUTOGEN_NODES.index(peer_a)
    pos_peer_b = WG_AUTOGEN_NODES.index(peer_b)

    vpn_subnet = list(IPv4Network('169.254.0.0/16').subnets(new_prefix=24))[pos_peer_a]
    return list(IPv4Network(vpn_subnet).subnets(new_prefix=31))[pos_peer_b]