"""ifstats: get information about a wireless interface."""

import os
import pipes
import re


class InterfaceStats(object):
  """InterfaceStats collects statistics from a wireless interface."""

  def __init__(self, system=None, runner=None, interface=None):
    self.system = system
    self.run = runner
    self.interface = interface

  def IwLink(self, devname):
    """Invoke `iw dev <devname> link` and return its output as a string."""
    return self.run('iw dev {} link'.format(pipes.quote(devname)))

  def IwScan(self, devname):
    """Invoke `iw dev <devname> scan` and return its output as a string."""
    devname_quoted = pipes.quote(devname)
    text = self.run('iw dev {} scan dump'.format(devname_quoted))
    if not text:
      text = self.run('iw dev {} scan'.format(devname_quoted))
    return text

  def IpAddr(self):
    """Invoke `ip addr` in one-line mode and return output as a string."""
    return self.run('ip -o -f inet addr')

  def AirportI(self):
    """Gather information about the current wireless network from `airport`."""
    return self.run('airport -I')

  def AirportScan(self):
    """Gather information about other observable networks from `airport`."""
    return self.run('airport -s')

  def GatherDarwin(self):
    """Gather wireless network information on Darwin (Mac OS X)."""
    return {
        'airport': self.AirportI(),
        'airportscan': self.AirportScan(),
    }

  def GatherLinux(self):
    """Gather wireless network information on Linux."""
    outputs = {'ipaddr': self.IpAddr()}
    if self.interface is not None:
      outputs.update({
          'iwlink': self.IwLink(self.interface),
          'iwscan': self.IwScan(self.interface)
      })
      return outputs

    # If no interface was supplied, use the first connected one (like `airport`
    # does for you automatically.)
    iw_dev_raw = self.run('iw dev')
    for line in iw_dev_raw.splitlines():
      tokens = line.split()
      if len(tokens) >= 2 and tokens[0] == 'Interface':
        interface = tokens[1]
        try:
          outputs.update({
              'iwlink': self.IwLink(interface),
              'iwscan': self.IwScan(interface)
          })
          return outputs
        except ValueError:
          pass

    raise ValueError('No connected interfaces found.')

  def Gather(self):
    """Gather all the wireless network information we know how to."""
    if self.system == 'Darwin':
      return self.GatherDarwin()
    elif self.system == 'Linux':
      return self.GatherLinux()
    else:
      raise OSError('System {} unsupported for InterfaceStats'.format(
          self.system))

def ParseIwLink(text):
  ol = text.splitlines()

  # BSSID is in the first line, in an idiosyncratic format.
  # sample: Connected to d8:c7:c8:d7:72:30 (on wlan0)
  m = re.search(r'(\w{2}:){5}\w{2}', ol[0])
  if m:
    result = {'BSSID': m.group(0)}
  else:
    raise ValueError('dev was not connected.')

  for line in ol[1:]:
    try:
      key, value = line.split(':', 1)
      result[key.strip()] = value.strip()
    except ValueError:
      continue

  return result

def ParseIpAddr(text):
  ol = text.splitlines()
  result = {}
  for line in ol:
    _, interface, _, addr, _ = line.split(None, 4)
    result[interface] = addr

  return result


def ParseAirportI(text):
  result = {}
  for line in text.splitlines():
    try:
      key, value = [cell.strip() for cell in line.split(':', 1)]
      if key in ['agrCtlRSSI', 'agrCtlNoise']:
        result[key] = int(value)
      else:
        result[key] = value
    except ValueError:
      continue

  return result

def ParseAirportScan(text):
  # This is a simple fixed-width format.
  header = ['SSID', 'BSSID', 'RSSI', 'CHANNEL', 'HT', 'CC',
            'SECURITY (auth/unicast/group)']
  result = []

  chre = re.compile(r'\d+(?:,\+|-\d+)?')
  for line in text.splitlines():
    ssid, bssid, rssi, channel, ht, cc, security = (
        [cell.strip() for cell in (line[:32], line[33:50], line[51:55],
                                   line[56:63], line[64:66], line[67:69],
                                   line[70:])])

    # the scan sometimes includes comment lines. assume that anything that has
    # a valid channel isn't a comment line.
    if chre.match(channel):
      result += [[ssid, bssid, int(rssi), channel, ht, cc, security]]

  return [header] + result

def Parse(system, cache):
  if system == 'Darwin':
    return {
        'link': ParseAirportI(cache.get('airport')),
        'scan': ParseAirportScan(cache.get('airportscan'))
    }
  elif system == 'Linux':
    return {
        'link': ParseIwLink(cache.get('iwlink')),
        'addr': ParseIpAddr(cache.get('ipaddr'))
    }
  else:
    raise OSError('Attempt to parse cache from '
                  'unrecognized system {}'.format(system))

def Restore(report_dir):
  """Restore an InterfaceStats cache from data on the filesystem."""
  cache = {}

  apath = os.path.join(report_dir, 'airport')
  if os.path.exists(apath):
    system = 'Darwin'
    names = ['airport', 'airportscan']
  else:
    iwpath = os.path.join(report_dir, 'iwlink')
    if os.path.exists(iwpath):
      system = 'Linux'
      names = ['ipaddr', 'iwlink', 'iwscan']
    else:
      raise IOError('Could not open report in {}'.format(report_dir))

  for name in names:
    try:
      with open(os.path.join(report_dir, name)) as infile:
        cache[name] = infile.read()
    except IOError:
      cache[name] = ''

  return system, cache