"""InfluxDB component which allows you to get data from an Influx database."""
from datetime import timedelta
import logging

import voluptuous as vol

from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import (
    CONF_HOST,
    CONF_NAME,
    CONF_PASSWORD,
    CONF_PORT,
    CONF_SSL,
    CONF_UNIT_OF_MEASUREMENT,
    CONF_USERNAME,
    CONF_VALUE_TEMPLATE,
    CONF_VERIFY_SSL,
    STATE_UNKNOWN,
)
from homeassistant.exceptions import TemplateError
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity
from homeassistant.util import Throttle

from . import CONF_DB_NAME

_LOGGER = logging.getLogger(__name__)

DEFAULT_HOST = "localhost"
DEFAULT_PORT = 8086
DEFAULT_DATABASE = "home_assistant"
DEFAULT_SSL = False
DEFAULT_VERIFY_SSL = False
DEFAULT_GROUP_FUNCTION = "mean"
DEFAULT_FIELD = "value"

CONF_QUERIES = "queries"
CONF_GROUP_FUNCTION = "group_function"
CONF_FIELD = "field"
CONF_MEASUREMENT_NAME = "measurement"
CONF_WHERE = "where"

MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=60)

_QUERY_SCHEME = vol.Schema(
    {
        vol.Required(CONF_NAME): cv.string,
        vol.Required(CONF_MEASUREMENT_NAME): cv.string,
        vol.Required(CONF_WHERE): cv.template,
        vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string,
        vol.Optional(CONF_VALUE_TEMPLATE): cv.template,
        vol.Optional(CONF_DB_NAME, default=DEFAULT_DATABASE): cv.string,
        vol.Optional(CONF_GROUP_FUNCTION, default=DEFAULT_GROUP_FUNCTION): cv.string,
        vol.Optional(CONF_FIELD, default=DEFAULT_FIELD): cv.string,
    }
)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Required(CONF_QUERIES): [_QUERY_SCHEME],
        vol.Optional(CONF_HOST, default=DEFAULT_HOST): cv.string,
        vol.Optional(CONF_PORT, default=DEFAULT_PORT): cv.port,
        vol.Inclusive(CONF_USERNAME, "authentication"): cv.string,
        vol.Inclusive(CONF_PASSWORD, "authentication"): cv.string,
        vol.Optional(CONF_SSL, default=DEFAULT_SSL): cv.boolean,
        vol.Optional(CONF_VERIFY_SSL, default=DEFAULT_VERIFY_SSL): cv.boolean,
    }
)


def setup_platform(hass, config, add_entities, discovery_info=None):
    """Set up the InfluxDB component."""
    influx_conf = {
        "host": config[CONF_HOST],
        "password": config.get(CONF_PASSWORD),
        "port": config.get(CONF_PORT),
        "ssl": config.get(CONF_SSL),
        "username": config.get(CONF_USERNAME),
        "verify_ssl": config.get(CONF_VERIFY_SSL),
    }

    dev = []

    for query in config.get(CONF_QUERIES):
        sensor = InfluxSensor(hass, influx_conf, query)
        if sensor.connected:
            dev.append(sensor)

    add_entities(dev, True)


class InfluxSensor(Entity):
    """Implementation of a Influxdb sensor."""

    def __init__(self, hass, influx_conf, query):
        """Initialize the sensor."""
        from influxdb import InfluxDBClient, exceptions

        self._name = query.get(CONF_NAME)
        self._unit_of_measurement = query.get(CONF_UNIT_OF_MEASUREMENT)
        value_template = query.get(CONF_VALUE_TEMPLATE)
        if value_template is not None:
            self._value_template = value_template
            self._value_template.hass = hass
        else:
            self._value_template = None
        database = query.get(CONF_DB_NAME)
        self._state = None
        self._hass = hass

        where_clause = query.get(CONF_WHERE)
        where_clause.hass = hass

        influx = InfluxDBClient(
            host=influx_conf["host"],
            port=influx_conf["port"],
            username=influx_conf["username"],
            password=influx_conf["password"],
            database=database,
            ssl=influx_conf["ssl"],
            verify_ssl=influx_conf["verify_ssl"],
        )
        try:
            influx.query("SHOW SERIES LIMIT 1;")
            self.connected = True
            self.data = InfluxSensorData(
                influx,
                query.get(CONF_GROUP_FUNCTION),
                query.get(CONF_FIELD),
                query.get(CONF_MEASUREMENT_NAME),
                where_clause,
            )
        except exceptions.InfluxDBClientError as exc:
            _LOGGER.error(
                "Database host is not accessible due to '%s', please"
                " check your entries in the configuration file and"
                " that the database exists and is READ/WRITE",
                exc,
            )
            self.connected = False

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

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

    @property
    def unit_of_measurement(self):
        """Return the unit of measurement of this entity, if any."""
        return self._unit_of_measurement

    @property
    def should_poll(self):
        """Return the polling state."""
        return True

    def update(self):
        """Get the latest data from Influxdb and updates the states."""
        self.data.update()
        value = self.data.value
        if value is None:
            value = STATE_UNKNOWN
        if self._value_template is not None:
            value = self._value_template.render_with_possible_json_value(
                str(value), STATE_UNKNOWN
            )

        self._state = value


class InfluxSensorData:
    """Class for handling the data retrieval."""

    def __init__(self, influx, group, field, measurement, where):
        """Initialize the data object."""
        self.influx = influx
        self.group = group
        self.field = field
        self.measurement = measurement
        self.where = where
        self.value = None
        self.query = None

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update(self):
        """Get the latest data with a shell command."""
        _LOGGER.info("Rendering where: %s", self.where)
        try:
            where_clause = self.where.render()
        except TemplateError as ex:
            _LOGGER.error("Could not render where clause template: %s", ex)
            return

        self.query = "select {}({}) as value from {} where {}".format(
            self.group, self.field, self.measurement, where_clause
        )

        _LOGGER.info("Running query: %s", self.query)

        points = list(self.influx.query(self.query).get_points())
        if not points:
            _LOGGER.warning(
                "Query returned no points, sensor state set " "to UNKNOWN: %s",
                self.query,
            )
            self.value = None
        else:
            if len(points) > 1:
                _LOGGER.warning(
                    "Query returned multiple points, only first " "one shown: %s",
                    self.query,
                )
            self.value = points[0].get("value")