"""
homeassistant.components.device_tracker.aruba
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Device tracker platform that supports scanning a Aruba Access Point for device
presence.

This device tracker needs telnet to be enabled on the router.

Configuration:

To use the Aruba tracker you will need to add something like the following
to your configuration.yaml file. You also need to enable Telnet in the
configuration page of your router.

device_tracker:
  platform: aruba
  host: YOUR_ACCESS_POINT_IP
  username: YOUR_ADMIN_USERNAME
  password: YOUR_ADMIN_PASSWORD

Variables:

host
*Required
The IP address of your router, e.g. 192.168.1.1.

username
*Required
The username of an user with administrative privileges, usually 'admin'.

password
*Required
The password for your given admin account.
"""
import logging
from datetime import timedelta
import re
import threading
import telnetlib

from homeassistant.const import CONF_HOST, CONF_USERNAME, CONF_PASSWORD
from homeassistant.helpers import validate_config
from homeassistant.util import Throttle
from homeassistant.components.device_tracker import DOMAIN

# Return cached results if last scan was less then this time ago
MIN_TIME_BETWEEN_SCANS = timedelta(seconds=10)

_LOGGER = logging.getLogger(__name__)

_DEVICES_REGEX = re.compile(
    r'(?P<name>([^\s]+))\s+' +
    r'(?P<ip>([0-9]{1,3}[\.]){3}[0-9]{1,3})\s+' +
    r'(?P<mac>(([0-9a-f]{2}[:-]){5}([0-9a-f]{2})))\s+')


# pylint: disable=unused-argument
def get_scanner(hass, config):
    """ Validates config and returns a Aruba scanner. """
    if not validate_config(config,
                           {DOMAIN: [CONF_HOST, CONF_USERNAME, CONF_PASSWORD]},
                           _LOGGER):
        return None

    scanner = ArubaDeviceScanner(config[DOMAIN])

    return scanner if scanner.success_init else None


class ArubaDeviceScanner(object):
    """ This class queries a Aruba Acces Point for connected devices. """
    def __init__(self, config):
        self.host = config[CONF_HOST]
        self.username = config[CONF_USERNAME]
        self.password = config[CONF_PASSWORD]

        self.lock = threading.Lock()

        self.last_results = {}

        # Test the router is accessible
        data = self.get_aruba_data()
        self.success_init = data is not None

    def scan_devices(self):
        """
        Scans for new devices and return a list containing found device IDs.
        """

        self._update_info()
        return [client['mac'] for client in self.last_results]

    def get_device_name(self, device):
        """ Returns the name of the given device or None if we don't know. """
        if not self.last_results:
            return None
        for client in self.last_results:
            if client['mac'] == device:
                return client['name']
        return None

    @Throttle(MIN_TIME_BETWEEN_SCANS)
    def _update_info(self):
        """
        Ensures the information from the Aruba Access Point is up to date.
        Returns boolean if scanning successful.
        """
        if not self.success_init:
            return False

        with self.lock:
            data = self.get_aruba_data()
            if not data:
                return False

            self.last_results = data.values()
            return True

    def get_aruba_data(self):
        """ Retrieve data from Aruba Access Point and return parsed result. """
        try:
            telnet = telnetlib.Telnet(self.host)
            telnet.read_until(b'User: ')
            telnet.write((self.username + '\r\n').encode('ascii'))
            telnet.read_until(b'Password: ')
            telnet.write((self.password + '\r\n').encode('ascii'))
            telnet.read_until(b'#')
            telnet.write(('show clients\r\n').encode('ascii'))
            devices_result = telnet.read_until(b'#').split(b'\r\n')
            telnet.write('exit\r\n'.encode('ascii'))
        except EOFError:
            _LOGGER.exception("Unexpected response from router")
            return
        except ConnectionRefusedError:
            _LOGGER.exception("Connection refused by router," +
                              " is telnet enabled?")
            return

        devices = {}
        for device in devices_result:
            match = _DEVICES_REGEX.search(device.decode('utf-8'))
            if match:
                devices[match.group('ip')] = {
                    'ip': match.group('ip'),
                    'mac': match.group('mac').upper(),
                    'name': match.group('name')
                    }
        return devices