#!/usr/bin/env python3
#
# Copyright (C) 2021 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import os

from sys import argv
from sys import exit

from vyos.configtree import ConfigTree

if __name__ == '__main__':
    if (len(argv) < 1):
        print("Must specify file name!")
        exit(1)

    file_name = argv[1]

    with open(file_name, 'r') as f:
        config_file = f.read()

    config = ConfigTree(config_file)
    base = ['interfaces', 'wirelessmodem']
    if not config.exists(base):
        # Nothing to do
        exit(0)

    new_base = ['interfaces', 'wwan']
    config.set(new_base)
    config.set_tag(new_base)
    for interface in config.list_nodes(base):
        # convert usb0b1.3p1.2 device identifier and extract 1.3 usb bus id
        usb = config.return_value(base + [interface, 'device'])
        device = usb.split('b')[-1]
        busid = device.split('p')[0]
        for wwan in os.listdir('/sys/class/net'):
            # we are only interested in interfaces starting with wwan
            if not wwan.startswith('wwan'):
                continue
            device = os.readlink(f'/sys/class/net/{wwan}/device')
            device = device.split(':')[0]
            if busid in device:
                config.copy(base + [interface], new_base + [wwan])

    config.delete(base)

    # Now that we have copied the old wirelessmodem interfaces to wwan
    # we can start to migrate also individual config items.
    for interface in config.list_nodes(new_base):
        # we do no longer need the USB device name
        config.delete(new_base + [interface, 'device'])
        # set/unset DNS configuration
        dns = new_base + [interface, 'no-peer-dns']
        if config.exists(dns):
            config.delete(dns)
        else:
            config.set(['system', 'name-servers-dhcp'], value=interface, replace=False)

        # the new wwan interface use regular IP addressing
        config.set(new_base + [interface, 'address'], value='dhcp')

    try:
        with open(file_name, 'w') as f:
            f.write(config.to_string())
    except OSError as e:
        print("Failed to save the modified config: {}".format(e))
        exit(1)