"""
Support for getting the disk temperature of a host.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/sensor.hddtemp/
"""
import logging
from datetime import timedelta
from telnetlib import Telnet

import voluptuous as vol

import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity
from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import (
    CONF_NAME, CONF_HOST, CONF_PORT, TEMP_CELSIUS, TEMP_FAHRENHEIT,
    STATE_UNKNOWN)

_LOGGER = logging.getLogger(__name__)

ATTR_DEVICE = 'device'
ATTR_MODEL = 'model'

CONF_DISKS = 'disks'

DEFAULT_HOST = 'localhost'
DEFAULT_PORT = 7634
DEFAULT_NAME = 'HD Temperature'
DEFAULT_TIMEOUT = 5

SCAN_INTERVAL = timedelta(minutes=1)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
    vol.Optional(CONF_DISKS, default=[]):
        vol.All(cv.ensure_list, [cv.string]),
    vol.Optional(CONF_HOST, default=DEFAULT_HOST): cv.string,
    vol.Optional(CONF_PORT, default=DEFAULT_PORT): cv.port,
    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
})


def setup_platform(hass, config, add_devices, discovery_info=None):
    """Set up the HDDTemp sensor."""
    name = config.get(CONF_NAME)
    host = config.get(CONF_HOST)
    port = config.get(CONF_PORT)
    disks = config.get(CONF_DISKS)

    try:
        hddtemp = HddTempData(host, port)
        hddtemp.update()
    except RuntimeError:
        _LOGGER.error("Unable to fetch the data from %s:%s", host, port)
        return False

    if not disks:
        disks = [next(iter(hddtemp.data)).split('|')[0]]

    dev = []
    for disk in disks:
        if disk in hddtemp.data:
            dev.append(HddTempSensor(name, disk, hddtemp))
        else:
            continue

    add_devices(dev, True)


class HddTempSensor(Entity):
    """Representation of a HDDTemp sensor."""

    def __init__(self, name, disk, hddtemp):
        """Initialize a HDDTemp sensor."""
        self.hddtemp = hddtemp
        self.disk = disk
        self._name = '{} {}'.format(name, disk)
        self._state = None
        self._details = None

    @property
    def name(self):
        """Return the name of the sensor."""
        return self._name

    @property
    def state(self):
        """Return the state of the device."""
        return self._state

    @property
    def unit_of_measurement(self):
        """Return the unit the value is expressed in."""
        if self._details[3] == 'C':
            return TEMP_CELSIUS
        return TEMP_FAHRENHEIT

    @property
    def device_state_attributes(self):
        """Return the state attributes of the sensor."""
        return {
            ATTR_DEVICE: self._details[0],
            ATTR_MODEL: self._details[1],
        }

    def update(self):
        """Get the latest data from HDDTemp daemon and updates the state."""
        self.hddtemp.update()

        if self.disk in self.hddtemp.data:
            self._details = self.hddtemp.data[self.disk].split('|')
            self._state = self._details[2]
        else:
            self._state = STATE_UNKNOWN


class HddTempData(object):
    """Get the latest data from HDDTemp and update the states."""

    def __init__(self, host, port):
        """Initialize the data object."""
        self.host = host
        self.port = port
        self.data = None

    def update(self):
        """Get the latest data from HDDTemp running as daemon."""
        try:
            connection = Telnet(
                host=self.host, port=self.port, timeout=DEFAULT_TIMEOUT)
            data = connection.read_all().decode(
                'ascii').lstrip('|').rstrip('|').split('||')
            self.data = {data[i].split('|')[0]: data[i]
                         for i in range(0, len(data), 1)}
        except ConnectionRefusedError:
            _LOGGER.error(
                "HDDTemp is not available at %s:%s", self.host, self.port)
            self.data = None