"""Support for MQTT room presence detection."""
import logging
import json
from datetime import timedelta

import voluptuous as vol

from homeassistant.components import mqtt
import homeassistant.helpers.config_validation as cv
from homeassistant.components.mqtt import CONF_STATE_TOPIC
from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import CONF_NAME, CONF_TIMEOUT, STATE_NOT_HOME, ATTR_ID
from homeassistant.core import callback
from homeassistant.helpers.entity import Entity
from homeassistant.util import dt, slugify

_LOGGER = logging.getLogger(__name__)

ATTR_DEVICE_ID = "device_id"
ATTR_DISTANCE = "distance"
ATTR_ROOM = "room"

CONF_DEVICE_ID = "device_id"
CONF_AWAY_TIMEOUT = "away_timeout"

DEFAULT_AWAY_TIMEOUT = 0
DEFAULT_NAME = "Room Sensor"
DEFAULT_TIMEOUT = 5
DEFAULT_TOPIC = "room_presence"

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Required(CONF_DEVICE_ID): cv.string,
        vol.Required(CONF_TIMEOUT, default=DEFAULT_TIMEOUT): cv.positive_int,
        vol.Optional(CONF_AWAY_TIMEOUT, default=DEFAULT_AWAY_TIMEOUT): cv.positive_int,
        vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
    }
).extend(mqtt.MQTT_RO_PLATFORM_SCHEMA.schema)

MQTT_PAYLOAD = vol.Schema(
    vol.All(
        json.loads,
        vol.Schema(
            {
                vol.Required(ATTR_ID): cv.string,
                vol.Required(ATTR_DISTANCE): vol.Coerce(float),
            },
            extra=vol.ALLOW_EXTRA,
        ),
    )
)


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up MQTT room Sensor."""
    async_add_entities(
        [
            MQTTRoomSensor(
                config.get(CONF_NAME),
                config.get(CONF_STATE_TOPIC),
                config.get(CONF_DEVICE_ID),
                config.get(CONF_TIMEOUT),
                config.get(CONF_AWAY_TIMEOUT),
            )
        ]
    )


class MQTTRoomSensor(Entity):
    """Representation of a room sensor that is updated via MQTT."""

    def __init__(self, name, state_topic, device_id, timeout, consider_home):
        """Initialize the sensor."""
        self._state = STATE_NOT_HOME
        self._name = name
        self._state_topic = "{}{}".format(state_topic, "/+")
        self._device_id = slugify(device_id).upper()
        self._timeout = timeout
        self._consider_home = (
            timedelta(seconds=consider_home) if consider_home else None
        )
        self._distance = None
        self._updated = None

    async def async_added_to_hass(self):
        """Subscribe to MQTT events."""

        @callback
        def update_state(device_id, room, distance):
            """Update the sensor state."""
            self._state = room
            self._distance = distance
            self._updated = dt.utcnow()

            self.async_schedule_update_ha_state()

        @callback
        def message_received(msg):
            """Handle new MQTT messages."""
            try:
                data = MQTT_PAYLOAD(msg.payload)
            except vol.MultipleInvalid as error:
                _LOGGER.debug("Skipping update because of malformatted data: %s", error)
                return

            device = _parse_update_data(msg.topic, data)
            if device.get(CONF_DEVICE_ID) == self._device_id:
                if self._distance is None or self._updated is None:
                    update_state(**device)
                else:
                    # update if:
                    # device is in the same room OR
                    # device is closer to another room OR
                    # last update from other room was too long ago
                    timediff = dt.utcnow() - self._updated
                    if (
                        device.get(ATTR_ROOM) == self._state
                        or device.get(ATTR_DISTANCE) < self._distance
                        or timediff.seconds >= self._timeout
                    ):
                        update_state(**device)

        return await mqtt.async_subscribe(
            self.hass, self._state_topic, message_received, 1
        )

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

    @property
    def device_state_attributes(self):
        """Return the state attributes."""
        return {ATTR_DISTANCE: self._distance}

    @property
    def state(self):
        """Return the current room of the entity."""
        return self._state

    def update(self):
        """Update the state for absent devices."""
        if (
            self._updated
            and self._consider_home
            and dt.utcnow() - self._updated > self._consider_home
        ):
            self._state = STATE_NOT_HOME


def _parse_update_data(topic, data):
    """Parse the room presence update."""
    parts = topic.split("/")
    room = parts[-1]
    device_id = slugify(data.get(ATTR_ID)).upper()
    distance = data.get("distance")
    parsed_data = {ATTR_DEVICE_ID: device_id, ATTR_ROOM: room, ATTR_DISTANCE: distance}
    return parsed_data
