#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
  szym / Oct 2009

  NetworkManager is not good enough when the APs are half-broken
  (e.g., don't associate, don't give DHCP leases or don't route).

  This is a really shoddy script that replaces NetworkManager.
  Manual network configuration is simple:
    iwconfig {iface} essid {essid} ap {mac}
    dhclient {iface}
  ... except that you need to parse `iwlist {iface} scan` for the
  relevant data. This quickly becomes tedious when there are
  n-teen cells in the scan results and most of them are broken.
"""

from os import popen, system

class WifiSelector:
  def __init__(self, iface):
    # test iface first
    #if(system("ls /sys/class/net/%s/wireless >/dev/null" % iface) != 0):
    #  raise Exception("%s is not wireless" % iface)
    self.iface = iface
    self.aps = []


  def scan(self):
    """ iwlist {iface} scan
        parse output and store in aps
    """
    aps = []
    cur = None
    for l in popen("iwlist %s scan" % self.iface):
      l = l.strip()
      if (not l):
        continue
      if (l.startswith('Cell')):
        if (cur != None):
          aps.append(cur)
        keys = [ 'essid','mode','chan','key','q','sig','noise','last' ]
        cur = dict([(x, None) for x in keys])
        cur['last'] = -1
        cur['ap'] = l.split()[4]
      if (cur == None):
        continue
      if (l.startswith('ESSID')):
        cur['essid'] = l.split(':')[1]
      if (l.startswith('Mode')):
        cur['mode'] = l.split(':')[1]
      if (l.startswith('Channel')):
        cur['chan'] = int(l.split(':')[1])
      if (l.startswith('Encryption')):
        cur['key'] = l.split(':')[1]
      if (l.startswith('Quality')):
        # Quality=15/100  Signal level:-84 dBm  Noise level=-90 dBm
        ls = l.replace(':', ' ').replace('/', ' ').replace('=', ' ').split()
        cur['q'] = int(ls[1])
        cur['sig'] = int(ls[5])
        #cur['noise'] = int(ls[9])
      if (l.startswith('Extra: Last beacon:')):
        #Extra: Last beacon: 1888ms ago
        cur['last'] = int(l.split()[3][:-2])
    self.aps = aps

  def show(self):
    """ pretty print aps
    """
    for i, ap in enumerate(self.aps):
      print i, ("%(mode)-6s %(key)-3s %(q)2d %(essid)-30s "
                "%(chan)4s %(ap)s %(last)5d" % ap)

  def sortq(self):
    """ sort aps by quality
    """
    self.aps.sort(key=lambda d: d['q'], reverse=True)

  def refresh(self):
    self.scan()
    self.sortq()
    self.show()

  def select(self, i):
    """ attempt to associate with aps[i]
    """
    ap = self.aps[i]
    cmd = "iwconfig "+self.iface+" mode %(mode)s essid %(essid)s ap %(ap)s" % ap
    print cmd
    system(cmd)
    system("dhclient %s" % self.iface)

  def kill_nm(self):
    if (system("/etc/init.d/network-manager status") == 0):
      system("/etc/init.d/network-manager stop")
      system("ifconfig %s up" % self.iface)

def main(args):
  from sys import stderr
  if (len(args) > 1 and args[1] == '-h'):
    print >> stderr, "Usage: %s {iface}" % args[0]
    return -1

  if len(args) < 2:
    iface = 'wlan0'
  else:
    iface = args[1]
  ws = WifiSelector(iface)
  #ws.kill_nm()
  ws.refresh()

  while(True):
    try:
      which = raw_input('select (default: refresh): ')
    except:
      break
    if len(which) == 0:
      ws.refresh()
    elif (int(which) >= 0 and int(which) < len(ws.aps)):
      ws.select(int(which))

if (__name__ == '__main__'):
  from sys import argv
  main(argv)