#!/usr/bin/python3

"""
Loop over a list of devies in a YAML file and print their OS version

sudo -H pip3 install napalm

inventory.yml:
---
# required: hostname, os
# optional: username, password, timeout, optional_args
R1:
  hostname: 192.168.223.2
  os: ios
  username: admin
  password: admin
  optional_args:
    secret: enable
    transport: telnet # Default is SSH
    port: 23
    verbose: True
R2:
  hostname: 192.168.188.2
  os: ios
"""


import argparse
from getpass import getpass
import napalm
import sys
import yaml


def parse_cli_args():

    parser = argparse.ArgumentParser(
        description='Loop over a list of devices in a YAML file and print the device firmware version',
        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
    )
    parser.add_argument(
        '-i', '--inventory-file',
        help='Input YAML inventory file',
        type=str,
        default='inventory.yml',
    )
    parser.add_argument(
        '-u', '--username',
        help='Default username for device access',
        type=str,
        default=None,
    )

    return vars(parser.parse_args())


def main():

    args = parse_cli_args()
    args['password'] = getpass("Default password:")


    try:
        inventory_file = open(args['inventory_file'])
    except Exception:
        print('Couldn\'t open inventory file {}'.format(args['inventory_file']))

    try:
        inventory = yaml.load(inventory_file)
    except Exception:
        return 1

    inventory_file.close()


    for dev, opt in inventory.items():

        if 'username' not in opt:
            if not args['username']:
                print ('No username specified')
                return 1
            else:
                opt['username'] = args['username']

        if 'password' not in opt:
            opt['password'] = args['password']

        if 'optional_args' not in opt:
            opt['optional_args'] = None

        driver = napalm.get_network_driver(opt['os'])
        opt.pop('os')

        with driver(**opt) as device:

            print('{}: {}'.format(opt['hostname'], device.get_facts()['os_version']))


    return 0


if __name__ == '__main__':
    sys.exit(main())