#
# CORE
# Copyright (c)2010-2012 the Boeing Company.
# See the LICENSE file included in this distribution.
#
# authors: core-dev@pf.itd.nrl.navy.mil
#

"""
netgraph.py: Netgraph helper functions; for now these are wrappers around
ngctl commands.
"""

import subprocess

from core import constants
from core.misc import utils

utils.checkexec([constants.NGCTL_BIN])


def createngnode(type, hookstr, name=None):
    """
    Create a new Netgraph node of type and optionally assign name. The
    hook string hookstr should contain two names. This is a string so
    other commands may be inserted after the two names.
    Return the name and netgraph ID of the new node.
    """
    hook1 = hookstr.split()[0]
    ngcmd = "mkpeer %s %s \n show .%s" % (type, hookstr, hook1)
    cmd = [constants.NGCTL_BIN, "-f", "-"]
    cmdid = subprocess.Popen(cmd, stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT)
    # err will always be None
    result, err = cmdid.communicate(input=ngcmd)
    status = cmdid.wait()
    if status > 0:
        raise Exception("error creating Netgraph node %s (%s): %s" % (type, ngcmd, result))
    results = result.split()
    ngname = results[1]
    ngid = results[5]
    if name:
        utils.check_call([constants.NGCTL_BIN, "name", "[0x%s]:" % ngid, name])
    return ngname, ngid


def destroyngnode(name):
    """ Shutdown a Netgraph node having the given name.
    """
    utils.check_call([constants.NGCTL_BIN, "shutdown", "%s:" % name])


def connectngnodes(name1, name2, hook1, hook2):
    """ Connect two hooks of two Netgraph nodes given by their names.
    """
    node1 = "%s:" % name1
    node2 = "%s:" % name2
    utils.check_call([constants.NGCTL_BIN, "connect", node1, node2, hook1, hook2])


def ngmessage(name, msg):
    """ Send a Netgraph message to the node named name.
    """
    cmd = [constants.NGCTL_BIN, "msg", "%s:" % name] + msg
    utils.check_call(cmd)


def ngloadkernelmodule(name):
    """ Load a kernel module by invoking kldstat. This is needed for the
        ng_ether module which automatically creates Netgraph nodes when loaded.
    """
    utils.mutecall(["kldload", name])