#!/usr/bin/env python2

import os
import sys
import time

__author__ = 'Faried Nawaz'
__version_ = '20030625'


def usage(str=None):
    if str:
        sys.stderr.write(str + '\n');
    sys.stderr.write('usage: istats.py interface-name\n')

def doit(interface):
    """Do the work."""

    cmd = '/sbin/ifconfig %s' % interface
    addr = ''
    basei = 0
    baseo = 0

    p = os.popen(cmd)
    lines = p.readlines()
    p.close()
    ltemp = lines[6].split()
    basei = long(ltemp[1].replace('bytes:', ''))
    baseo = long(ltemp[5].replace('bytes:', ''))
    print '''%-4s  %9s  %9s
%-4s  %9ld  %9ld''' % ('Name', 'In', 'Out',
           interface, basei, baseo)

    while 1:
        time.sleep(1)
        p = os.popen(cmd)
        lines = p.readlines()
        p.close()
        ltemp = lines[6].split()
        ipkts = long(ltemp[1].replace('bytes:', '')) - basei
        opkts = long(ltemp[5].replace('bytes:', '')) - baseo
        basei = long(ltemp[1].replace('bytes:', ''))
        baseo = long(ltemp[5].replace('bytes:', ''))
        print '%-4s  %9ld  %9ld' % (interface, ipkts, opkts)
        
    
def main(args):
    """Main branching logic."""
    if len(args) == 0:
        usage()
        sys.exit(1)

    # check if the interface exists
    p = os.popen('ifconfig %s 2>&1' % args[0]);
    line = p.readline()
    p.close()

    if line.startswith('ifconfig: '):
        usage('no such interface: ' + args[0])
        sys.exit(1)
    else:
        doit(args[0])


if __name__ == '__main__': main(sys.argv[1:])