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

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/device_tracker.aruba/
"""
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