"""
Support for MQTT locks.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/lock.mqtt/
"""
import asyncio
import logging

import voluptuous as vol

from homeassistant.core import callback
from homeassistant.components.lock import LockDevice
from homeassistant.components.mqtt import (
    CONF_STATE_TOPIC, CONF_COMMAND_TOPIC, CONF_QOS, CONF_RETAIN)
from homeassistant.const import (
    CONF_NAME, CONF_OPTIMISTIC, CONF_VALUE_TEMPLATE)
import homeassistant.components.mqtt as mqtt
import homeassistant.helpers.config_validation as cv

_LOGGER = logging.getLogger(__name__)

CONF_PAYLOAD_LOCK = 'payload_lock'
CONF_PAYLOAD_UNLOCK = 'payload_unlock'

DEFAULT_NAME = 'MQTT Lock'
DEFAULT_OPTIMISTIC = False
DEFAULT_PAYLOAD_LOCK = 'LOCK'
DEFAULT_PAYLOAD_UNLOCK = 'UNLOCK'
DEPENDENCIES = ['mqtt']

PLATFORM_SCHEMA = mqtt.MQTT_RW_PLATFORM_SCHEMA.extend({
    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
    vol.Optional(CONF_PAYLOAD_LOCK, default=DEFAULT_PAYLOAD_LOCK):
        cv.string,
    vol.Optional(CONF_PAYLOAD_UNLOCK, default=DEFAULT_PAYLOAD_UNLOCK):
        cv.string,
    vol.Optional(CONF_OPTIMISTIC, default=DEFAULT_OPTIMISTIC): cv.boolean,
})


@asyncio.coroutine
def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
    """Set up the MQTT lock."""
    value_template = config.get(CONF_VALUE_TEMPLATE)
    if value_template is not None:
        value_template.hass = hass

    async_add_devices([MqttLock(
        config.get(CONF_NAME),
        config.get(CONF_STATE_TOPIC),
        config.get(CONF_COMMAND_TOPIC),
        config.get(CONF_QOS),
        config.get(CONF_RETAIN),
        config.get(CONF_PAYLOAD_LOCK),
        config.get(CONF_PAYLOAD_UNLOCK),
        config.get(CONF_OPTIMISTIC),
        value_template,
    )])


class MqttLock(LockDevice):
    """Representation of a lock that can be toggled using MQTT."""

    def __init__(self, name, state_topic, command_topic, qos, retain,
                 payload_lock, payload_unlock, optimistic, value_template):
        """Initialize the lock."""
        self._state = False
        self._name = name
        self._state_topic = state_topic
        self._command_topic = command_topic
        self._qos = qos
        self._retain = retain
        self._payload_lock = payload_lock
        self._payload_unlock = payload_unlock
        self._optimistic = optimistic
        self._template = value_template

    @asyncio.coroutine
    def async_added_to_hass(self):
        """Subscribe to MQTT events.

        This method is a coroutine.
        """
        @callback
        def message_received(topic, payload, qos):
            """Handle new MQTT messages."""
            if self._template is not None:
                payload = self._template.async_render_with_possible_json_value(
                    payload)
            if payload == self._payload_lock:
                self._state = True
            elif payload == self._payload_unlock:
                self._state = False

            self.async_schedule_update_ha_state()

        if self._state_topic is None:
            # Force into optimistic mode.
            self._optimistic = True
        else:
            yield from mqtt.async_subscribe(
                self.hass, self._state_topic, message_received, self._qos)

    @property
    def should_poll(self):
        """No polling needed."""
        return False

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

    @property
    def is_locked(self):
        """Return true if lock is locked."""
        return self._state

    @property
    def assumed_state(self):
        """Return true if we do optimistic updates."""
        return self._optimistic

    @asyncio.coroutine
    def async_lock(self, **kwargs):
        """Lock the device.

        This method is a coroutine.
        """
        mqtt.async_publish(
            self.hass, self._command_topic, self._payload_lock, self._qos,
            self._retain)
        if self._optimistic:
            # Optimistically assume that switch has changed state.
            self._state = True
            self.async_schedule_update_ha_state()

    @asyncio.coroutine
    def async_unlock(self, **kwargs):
        """Unlock the device.

        This method is a coroutine.
        """
        mqtt.async_publish(
            self.hass, self._command_topic, self._payload_unlock, self._qos,
            self._retain)
        if self._optimistic:
            # Optimistically assume that switch has changed state.
            self._state = False
            self.async_schedule_update_ha_state()
