"""Support for Dutch Smart Meter (also known as Smartmeter or P1 port)."""
import asyncio
from datetime import timedelta
from functools import partial
import logging

from dsmr_parser import obis_references as obis_ref
from dsmr_parser.clients.protocol import create_dsmr_reader, create_tcp_dsmr_reader
import serial
import voluptuous as vol

from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import CONF_HOST, CONF_PORT, EVENT_HOMEASSISTANT_STOP
from homeassistant.core import CoreState
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity

_LOGGER = logging.getLogger(__name__)

CONF_DSMR_VERSION = "dsmr_version"
CONF_RECONNECT_INTERVAL = "reconnect_interval"
CONF_PRECISION = "precision"

DEFAULT_DSMR_VERSION = "2.2"
DEFAULT_PORT = "/dev/ttyUSB0"
DEFAULT_PRECISION = 3

DOMAIN = "dsmr"

ICON_GAS = "mdi:fire"
ICON_POWER = "mdi:flash"
ICON_POWER_FAILURE = "mdi:flash-off"
ICON_SWELL_SAG = "mdi:pulse"

# Smart meter sends telegram every 10 seconds
MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=10)

RECONNECT_INTERVAL = 5

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Optional(CONF_PORT, default=DEFAULT_PORT): cv.string,
        vol.Optional(CONF_HOST): cv.string,
        vol.Optional(CONF_DSMR_VERSION, default=DEFAULT_DSMR_VERSION): vol.All(
            cv.string, vol.In(["5", "4", "2.2"])
        ),
        vol.Optional(CONF_RECONNECT_INTERVAL, default=30): int,
        vol.Optional(CONF_PRECISION, default=DEFAULT_PRECISION): vol.Coerce(int),
    }
)


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up the DSMR sensor."""
    # Suppress logging
    logging.getLogger("dsmr_parser").setLevel(logging.ERROR)

    dsmr_version = config[CONF_DSMR_VERSION]

    # Define list of name,obis mappings to generate entities
    obis_mapping = [
        ["Power Consumption", obis_ref.CURRENT_ELECTRICITY_USAGE],
        ["Power Production", obis_ref.CURRENT_ELECTRICITY_DELIVERY],
        ["Power Tariff", obis_ref.ELECTRICITY_ACTIVE_TARIFF],
        ["Power Consumption (total)", obis_ref.ELECTRICITY_IMPORTED_TOTAL],
        ["Power Consumption (low)", obis_ref.ELECTRICITY_USED_TARIFF_1],
        ["Power Consumption (normal)", obis_ref.ELECTRICITY_USED_TARIFF_2],
        ["Power Production (low)", obis_ref.ELECTRICITY_DELIVERED_TARIFF_1],
        ["Power Production (normal)", obis_ref.ELECTRICITY_DELIVERED_TARIFF_2],
        ["Power Consumption Phase L1", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L1_POSITIVE],
        ["Power Consumption Phase L2", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L2_POSITIVE],
        ["Power Consumption Phase L3", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L3_POSITIVE],
        ["Power Production Phase L1", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L1_NEGATIVE],
        ["Power Production Phase L2", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L2_NEGATIVE],
        ["Power Production Phase L3", obis_ref.INSTANTANEOUS_ACTIVE_POWER_L3_NEGATIVE],
        ["Long Power Failure Count", obis_ref.LONG_POWER_FAILURE_COUNT],
        ["Voltage Sags Phase L1", obis_ref.VOLTAGE_SAG_L1_COUNT],
        ["Voltage Sags Phase L2", obis_ref.VOLTAGE_SAG_L2_COUNT],
        ["Voltage Sags Phase L3", obis_ref.VOLTAGE_SAG_L3_COUNT],
        ["Voltage Swells Phase L1", obis_ref.VOLTAGE_SWELL_L1_COUNT],
        ["Voltage Swells Phase L2", obis_ref.VOLTAGE_SWELL_L2_COUNT],
        ["Voltage Swells Phase L3", obis_ref.VOLTAGE_SWELL_L3_COUNT],
        ["Voltage Phase L1", obis_ref.INSTANTANEOUS_VOLTAGE_L1],
        ["Voltage Phase L2", obis_ref.INSTANTANEOUS_VOLTAGE_L2],
        ["Voltage Phase L3", obis_ref.INSTANTANEOUS_VOLTAGE_L3],
    ]

    # Generate device entities
    devices = [DSMREntity(name, obis, config) for name, obis in obis_mapping]

    # Protocol version specific obis
    if dsmr_version in ("4", "5"):
        gas_obis = obis_ref.HOURLY_GAS_METER_READING
    else:
        gas_obis = obis_ref.GAS_METER_READING

    # Add gas meter reading and derivative for usage
    devices += [
        DSMREntity("Gas Consumption", gas_obis, config),
        DerivativeDSMREntity("Hourly Gas Consumption", gas_obis, config),
    ]

    async_add_entities(devices)

    def update_entities_telegram(telegram):
        """Update entities with latest telegram and trigger state update."""
        # Make all device entities aware of new telegram
        for device in devices:
            device.telegram = telegram
            hass.async_create_task(device.async_update_ha_state())

    # Creates an asyncio.Protocol factory for reading DSMR telegrams from
    # serial and calls update_entities_telegram to update entities on arrival
    if CONF_HOST in config:
        reader_factory = partial(
            create_tcp_dsmr_reader,
            config[CONF_HOST],
            config[CONF_PORT],
            config[CONF_DSMR_VERSION],
            update_entities_telegram,
            loop=hass.loop,
        )
    else:
        reader_factory = partial(
            create_dsmr_reader,
            config[CONF_PORT],
            config[CONF_DSMR_VERSION],
            update_entities_telegram,
            loop=hass.loop,
        )

    async def connect_and_reconnect():
        """Connect to DSMR and keep reconnecting until Home Assistant stops."""
        while hass.state != CoreState.stopping:
            # Start DSMR asyncio.Protocol reader
            try:
                transport, protocol = await hass.loop.create_task(reader_factory())
            except (
                serial.serialutil.SerialException,
                ConnectionRefusedError,
                TimeoutError,
            ):
                # Log any error while establishing connection and drop to retry
                # connection wait
                _LOGGER.exception("Error connecting to DSMR")
                transport = None

            if transport:
                # Register listener to close transport on HA shutdown
                stop_listener = hass.bus.async_listen_once(
                    EVENT_HOMEASSISTANT_STOP, transport.close
                )

                # Wait for reader to close
                await protocol.wait_closed()

            if hass.state != CoreState.stopping:
                # Unexpected disconnect
                if transport:
                    # remove listener
                    stop_listener()

                # Reflect disconnect state in devices state by setting an
                # empty telegram resulting in `unknown` states
                update_entities_telegram({})

                # throttle reconnect attempts
                await asyncio.sleep(config[CONF_RECONNECT_INTERVAL])

    # Can't be hass.async_add_job because job runs forever
    hass.loop.create_task(connect_and_reconnect())


class DSMREntity(Entity):
    """Entity reading values from DSMR telegram."""

    def __init__(self, name, obis, config):
        """Initialize entity."""
        self._name = name
        self._obis = obis
        self._config = config
        self.telegram = {}

    def get_dsmr_object_attr(self, attribute):
        """Read attribute from last received telegram for this DSMR object."""
        # Make sure telegram contains an object for this entities obis
        if self._obis not in self.telegram:
            return None

        # Get the attribute value if the object has it
        dsmr_object = self.telegram[self._obis]
        return getattr(dsmr_object, attribute, None)

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

    @property
    def icon(self):
        """Icon to use in the frontend, if any."""
        if "Sags" in self._name or "Swells" in self.name:
            return ICON_SWELL_SAG
        if "Failure" in self._name:
            return ICON_POWER_FAILURE
        if "Power" in self._name:
            return ICON_POWER
        if "Gas" in self._name:
            return ICON_GAS

    @property
    def state(self):
        """Return the state of sensor, if available, translate if needed."""
        value = self.get_dsmr_object_attr("value")

        if self._obis == obis_ref.ELECTRICITY_ACTIVE_TARIFF:
            return self.translate_tariff(value)

        try:
            value = round(float(value), self._config[CONF_PRECISION])
        except TypeError:
            pass

        if value is not None:
            return value

        return None

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

    @staticmethod
    def translate_tariff(value):
        """Convert 2/1 to normal/low."""
        # DSMR V2.2: Note: Rate code 1 is used for low rate and rate code 2 is
        # used for normal rate.
        if value == "0002":
            return "normal"
        if value == "0001":
            return "low"

        return None


class DerivativeDSMREntity(DSMREntity):
    """Calculated derivative for values where the DSMR doesn't offer one.

    Gas readings are only reported per hour and don't offer a rate only
    the current meter reading. This entity converts subsequents readings
    into a hourly rate.
    """

    _previous_reading = None
    _previous_timestamp = None
    _state = None

    @property
    def state(self):
        """Return the calculated current hourly rate."""
        return self._state

    async def async_update(self):
        """Recalculate hourly rate if timestamp has changed.

        DSMR updates gas meter reading every hour. Along with the new
        value a timestamp is provided for the reading. Test if the last
        known timestamp differs from the current one then calculate a
        new rate for the previous hour.

        """
        # check if the timestamp for the object differs from the previous one
        timestamp = self.get_dsmr_object_attr("datetime")
        if timestamp and timestamp != self._previous_timestamp:
            current_reading = self.get_dsmr_object_attr("value")

            if self._previous_reading is None:
                # Can't calculate rate without previous datapoint
                # just store current point
                pass
            else:
                # Recalculate the rate
                diff = current_reading - self._previous_reading
                timediff = timestamp - self._previous_timestamp
                total_seconds = timediff.total_seconds()
                self._state = round(float(diff) / total_seconds * 3600, 3)

            self._previous_reading = current_reading
            self._previous_timestamp = timestamp

    @property
    def unit_of_measurement(self):
        """Return the unit of measurement of this entity, per hour, if any."""
        unit = self.get_dsmr_object_attr("unit")
        if unit:
            return unit + "/h"
