# -*- coding: utf-8 -*-

# Copyright 2014 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import glob
import logging
import os
import re

from oslo_concurrency import processutils


logger = logging.getLogger(__name__)
_SYS_CLASS_NET = '/sys/class/net'


class OvsDpdkBindException(ValueError):
    pass


def write_config(filename, data):
    with open(filename, 'w') as f:
        f.write(str(data))


def get_file_data(filename):
    if not os.path.exists(filename):
        return ''

    try:
        with open(filename, 'r') as f:
            return f.read()
    except IOError:
        logger.error("Error reading file: %s" % filename)
        return ''


def interface_mac(name):
    try:  # If the iface is part of a Linux bond, the real MAC is only here.
        with open('/sys/class/net/%s/bonding_slave/perm_hwaddr' % name,
                  'r') as f:
            return f.read().rstrip()
    except IOError:
        pass  # Iface is not part of a bond, continue

    try:
        with open('/sys/class/net/%s/address' % name, 'r') as f:
            return f.read().rstrip()
    except IOError:
        logger.error("Unable to read mac address: %s" % name)
        raise


def _is_active_nic(interface_name):
    try:
        if interface_name == 'lo':
            return False

        device_dir = _SYS_CLASS_NET + '/%s/device' % interface_name
        has_device_dir = os.path.isdir(device_dir)

        operstate = None
        with open(_SYS_CLASS_NET + '/%s/operstate' % interface_name, 'r') as f:
            operstate = f.read().rstrip().lower()

        address = None
        with open(_SYS_CLASS_NET + '/%s/address' % interface_name, 'r') as f:
            address = f.read().rstrip()

        if has_device_dir and operstate == 'up' and address:
            return True
        else:
            return False
    except IOError:
        return False


def _natural_sort_key(s):
    nsre = re.compile('([0-9]+)')
    return [int(text) if text.isdigit() else text
            for text in re.split(nsre, s)]


def ordered_active_nics():
    embedded_nics = []
    nics = []
    logger.debug("Finding active nics")
    for name in glob.iglob(_SYS_CLASS_NET + '/*'):
        nic = name[(len(_SYS_CLASS_NET) + 1):]
        if _is_active_nic(nic):
            if nic.startswith('em') or nic.startswith('eth') or \
                    nic.startswith('eno'):
                logger.debug("%s is an embedded active nic" % nic)
                embedded_nics.append(nic)
            else:
                logger.debug("%s is an active nic" % nic)
                nics.append(nic)
        else:
            logger.debug("%s is not an active nic" % nic)
    # NOTE: we could just natural sort all active devices,
    # but this ensures em, eno, and eth are ordered first
    # (more backwards compatible)
    active_nics = (sorted(embedded_nics, key=_natural_sort_key) +
                   sorted(nics, key=_natural_sort_key))
    logger.debug("Active nics are %s" % active_nics)
    return active_nics


def diff(filename, data):
    file_data = get_file_data(filename)
    logger.debug("Diff file data:\n%s" % file_data)
    logger.debug("Diff data:\n%s" % data)
    # convert to string as JSON may have unicode in it
    return not file_data == data


def bind_dpdk_interfaces(ifname, driver, noop):
    pci_addres = _get_pci_address(ifname, noop)
    if not noop:
        if pci_addres:
            # modbprobe of the driver has to be done before binding.
            # for reboots, puppet will add the modprobe to /etc/rc.modules
            processutils.execute('modprobe', 'vfio-pci')

            out, err = processutils.execute('driverctl', 'set-override',
                                            pci_addres, driver)
            if err:
                msg = "Failed to bind interface %s with dpdk" % ifname
                raise OvsDpdkBindException(msg)
            else:
                processutils.execute('driverctl', 'load-override', pci_addres)
    else:
        logger.info('Interface %(name)s bound to DPDK driver %(driver)s '
                    'using driverctl command' %
                    {'name': ifname, 'driver': driver})


def _get_pci_address(ifname, noop):
    # TODO(skramaja): Validate if the given interface supports dpdk
    if not noop:
        # If ifname is already bound, then ethtool will not be able to list the
        # device, in which case, binding is already done, proceed with scripts
        out, err = processutils.execute('ethtool', '-i', ifname)
        if not err:
            for item in out.split('\n'):
                if 'bus-info' in item:
                    return item.split(' ')[1]
    else:
        logger.info('Fetch the PCI address of the interface %s using '
                    'ethtool' % ifname)