#!/usr/bin/env python

import argparse
import math
import os
import random

import libvirt

templatedir = os.getenv('LIB', '/var/opt/opnfv/lib') + '/installer/'

MAX_NUM_MACS = math.trunc(0xff/2)


def generate_baremetal_macs(count=1):
    """Generate an Ethernet MAC address suitable for baremetal testing."""
    # NOTE(dprince): We generate our own bare metal MAC address's here
    # instead of relying on libvirt so that we can ensure the
    # locally administered bit is set low. (The libvirt default is
    # to set the 2nd MSB high.) This effectively allows our
    # fake baremetal VMs to more accurately behave like real hardware
    # and fixes issues with bridge/DHCP configurations which rely
    # on the fact that bridges assume the MAC address of the lowest
    # attached NIC.
    # MACs generated for a given machine will also be in sequential
    # order, which matches how most BM machines are laid out as well.
    # Additionally we increment each MAC by two places.
    macs = []

    if count > MAX_NUM_MACS:
        raise ValueError("The MAX num of MACS supported is %i." % MAX_NUM_MACS)

    base_nums = [0x00,
               random.randint(0x00, 0xff),
               random.randint(0x00, 0xff),
               random.randint(0x00, 0xff),
               random.randint(0x00, 0xff)]
    base_mac = ':'.join(map(lambda x: "%02x" % x, base_nums))

    start = random.randint(0x00, 0xff)
    if (start + (count * 2)) > 0xff:
        # leave room to generate macs in sequence
        start = 0xff - count * 2
    for num in range(0, count*2, 2):
        mac = start + num
        macs.append(base_mac + ":" + ("%02x" % mac))
    return macs

def main():
    parser = argparse.ArgumentParser(
        description="Configure a kvm virtual machine for the seed image.")
    parser.add_argument('--name', default='seed',
        help='the name to give the machine in libvirt.')
    parser.add_argument('--image',
        help='Use a custom image file (must be qcow2).')
    parser.add_argument('--diskbus', default='sata',
        help='Choose an alternate bus type for the disk')
    parser.add_argument('--baremetal-interface', nargs='+', default=['brbm'],
        help='The interface which bare metal nodes will be connected to.')
    parser.add_argument('--engine', default='kvm',
        help='The virtualization engine to use')
    parser.add_argument('--arch', default='i686',
        help='The architecture to use')
    parser.add_argument('--memory', default='2097152',
        help="Maximum memory for the VM in KB.")
    parser.add_argument('--cpus', default='1',
        help="CPU count for the VM.")
    parser.add_argument('--bootdev', default='hd',
        help="What boot device to use (hd/network).")
    parser.add_argument('--seed', default=False, action='store_true',
        help='Create a seed vm with two interfaces.')
    parser.add_argument('--ovsbridge', default="",
        help='Place the seed public interface on this ovs bridge.')
    parser.add_argument('--libvirt-nic-driver', default='virtio',
        help='The libvirt network driver to use')
    parser.add_argument('--enable-serial-console', action="store_true",
            help='Enable a serial console')
    parser.add_argument('--direct-boot',
            help='Enable directboot to <value>.{vmlinux & initrd}')
    parser.add_argument('--kernel-arg', action="append", dest='kernel_args',
            help='Kernel arguments, use multiple time for multiple args.')
    parser.add_argument('--uri', default='qemu:///system',
        help='The server uri with which to connect.')
    args = parser.parse_args()
    with file(templatedir + '/domain.xml', 'rb') as f:
        source_template = f.read()
    imagefile = '/var/lib/libvirt/images/seed.qcow2'
    if args.image:
        imagefile = args.image
    imagefile = os.path.realpath(imagefile)
    params = {
        'name': args.name,
        'imagefile': imagefile,
        'engine': args.engine,
        'arch': args.arch,
        'memory': args.memory,
        'cpus': args.cpus,
        'bootdev': args.bootdev,
        'network': '',
        'enable_serial_console': '',
        'direct_boot': '',
        'kernel_args': '',
        }
    if args.image is not None:
        params['imagefile'] = args.image

    # Configure the bus type for the target disk device
    params['diskbus'] = args.diskbus
    nicparams = {
        'nicdriver': args.libvirt_nic_driver,
        'ovsbridge': args.ovsbridge,
        }
    if args.seed:
        if args.ovsbridge:
            params['network'] = """
      <interface type='bridge'>
        <source bridge='%(ovsbridge)s'/>
        <virtualport type='openvswitch'/>
        <model type='%(nicdriver)s'/>
      </interface>""" % nicparams
        else:
            params['network'] = """
      <!-- regular natted network, for access to the vm -->
      <interface type='network'>
        <source network='default'/>
        <model type='%(nicdriver)s'/>
      </interface>""" % nicparams

    macs = generate_baremetal_macs(len(args.baremetal_interface))

    params['bm_network'] = ""
    for bm_interface, mac in zip(args.baremetal_interface, macs):
        bm_interface_params = {
            'bminterface': bm_interface,
            'bmmacaddress': mac,
            'nicdriver': args.libvirt_nic_driver,
            }
        params['bm_network'] += """
          <!-- bridged 'bare metal' network on %(bminterface)s -->
          <interface type='network'>
            <mac address='%(bmmacaddress)s'/>
            <source network='%(bminterface)s'/>
            <model type='%(nicdriver)s'/>
          </interface>""" % bm_interface_params

    if args.enable_serial_console:
        params['enable_serial_console'] = """
        <serial type='pty'>
          <target port='0'/>
        </serial>
        <console type='pty'>
          <target type='serial' port='0'/>
        </console>
        """
    if args.direct_boot:
        params['direct_boot'] = """
        <kernel>/var/lib/libvirt/images/%(direct_boot)s.vmlinuz</kernel>
        <initrd>/var/lib/libvirt/images/%(direct_boot)s.initrd</initrd>
        """ % { 'direct_boot': args.direct_boot }
    if args.kernel_args:
        params['kernel_args'] = """
        <cmdline>%s</cmdline>
        """ % ' '.join(args.kernel_args)

    libvirt_template = source_template % params
    conn=libvirt.open(args.uri)
    a = conn.defineXML(libvirt_template)
    print ("Created machine %s with UUID %s" % (args.name, a.UUIDString()))

if __name__ == '__main__':
    main()