"""Utility meter from sensors providing raw data."""
from datetime import date, datetime, timedelta
from decimal import Decimal, DecimalException
import logging

from croniter import croniter
import voluptuous as vol

from homeassistant.components.sensor import (
    ATTR_LAST_RESET,
    STATE_CLASS_MEASUREMENT,
    STATE_CLASS_TOTAL_INCREASING,
    SensorEntity,
)
from homeassistant.const import (
    ATTR_UNIT_OF_MEASUREMENT,
    CONF_NAME,
    DEVICE_CLASS_ENERGY,
    ENERGY_KILO_WATT_HOUR,
    ENERGY_WATT_HOUR,
    EVENT_HOMEASSISTANT_START,
    STATE_UNAVAILABLE,
    STATE_UNKNOWN,
)
from homeassistant.core import callback
from homeassistant.helpers import entity_platform
from homeassistant.helpers.dispatcher import async_dispatcher_connect
from homeassistant.helpers.event import (
    async_track_point_in_time,
    async_track_state_change_event,
    async_track_time_change,
)
from homeassistant.helpers.restore_state import RestoreEntity
import homeassistant.util.dt as dt_util

from .const import (
    ATTR_CRON_PATTERN,
    ATTR_VALUE,
    BIMONTHLY,
    CONF_CRON_PATTERN,
    CONF_METER,
    CONF_METER_NET_CONSUMPTION,
    CONF_METER_OFFSET,
    CONF_METER_TYPE,
    CONF_SOURCE_SENSOR,
    CONF_TARIFF,
    CONF_TARIFF_ENTITY,
    DAILY,
    DATA_UTILITY,
    HOURLY,
    MONTHLY,
    QUARTER_HOURLY,
    QUARTERLY,
    SERVICE_CALIBRATE_METER,
    SIGNAL_RESET_METER,
    WEEKLY,
    YEARLY,
)

_LOGGER = logging.getLogger(__name__)

ATTR_SOURCE_ID = "source"
ATTR_STATUS = "status"
ATTR_PERIOD = "meter_period"
ATTR_LAST_PERIOD = "last_period"
ATTR_TARIFF = "tariff"

DEVICE_CLASS_MAP = {
    ENERGY_WATT_HOUR: DEVICE_CLASS_ENERGY,
    ENERGY_KILO_WATT_HOUR: DEVICE_CLASS_ENERGY,
}

ICON = "mdi:counter"

PRECISION = 3
PAUSED = "paused"
COLLECTING = "collecting"


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up the utility meter sensor."""
    if discovery_info is None:
        _LOGGER.error("This platform is only available through discovery")
        return

    meters = []
    for conf in discovery_info:
        meter = conf[CONF_METER]
        conf_meter_source = hass.data[DATA_UTILITY][meter][CONF_SOURCE_SENSOR]
        conf_meter_type = hass.data[DATA_UTILITY][meter].get(CONF_METER_TYPE)
        conf_meter_offset = hass.data[DATA_UTILITY][meter][CONF_METER_OFFSET]
        conf_meter_net_consumption = hass.data[DATA_UTILITY][meter][
            CONF_METER_NET_CONSUMPTION
        ]
        conf_meter_tariff_entity = hass.data[DATA_UTILITY][meter].get(
            CONF_TARIFF_ENTITY
        )
        conf_cron_pattern = hass.data[DATA_UTILITY][meter].get(CONF_CRON_PATTERN)

        meters.append(
            UtilityMeterSensor(
                conf_meter_source,
                conf.get(CONF_NAME),
                conf_meter_type,
                conf_meter_offset,
                conf_meter_net_consumption,
                conf.get(CONF_TARIFF),
                conf_meter_tariff_entity,
                conf_cron_pattern,
            )
        )

    async_add_entities(meters)

    platform = entity_platform.async_get_current_platform()

    platform.async_register_entity_service(
        SERVICE_CALIBRATE_METER,
        {vol.Required(ATTR_VALUE): vol.Coerce(Decimal)},
        "async_calibrate",
    )


class UtilityMeterSensor(RestoreEntity, SensorEntity):
    """Representation of an utility meter sensor."""

    def __init__(
        self,
        source_entity,
        name,
        meter_type,
        meter_offset,
        net_consumption,
        tariff=None,
        tariff_entity=None,
        cron_pattern=None,
    ):
        """Initialize the Utility Meter sensor."""
        self._sensor_source_id = source_entity
        self._state = 0
        self._last_period = 0
        self._last_reset = dt_util.utcnow()
        self._collecting = None
        if name:
            self._name = name
        else:
            self._name = f"{source_entity} meter"
        self._unit_of_measurement = None
        self._period = meter_type
        self._period_offset = meter_offset
        self._cron_pattern = cron_pattern
        self._sensor_net_consumption = net_consumption
        self._tariff = tariff
        self._tariff_entity = tariff_entity

    @callback
    def async_reading(self, event):
        """Handle the sensor state changes."""
        old_state = event.data.get("old_state")
        new_state = event.data.get("new_state")
        if (
            old_state is None
            or new_state is None
            or old_state.state in [STATE_UNKNOWN, STATE_UNAVAILABLE]
            or new_state.state in [STATE_UNKNOWN, STATE_UNAVAILABLE]
        ):
            return

        self._unit_of_measurement = new_state.attributes.get(ATTR_UNIT_OF_MEASUREMENT)

        try:
            diff = Decimal(new_state.state) - Decimal(old_state.state)

            if (not self._sensor_net_consumption) and diff < 0:
                # Source sensor just rolled over for unknown reasons,
                return
            self._state += diff

        except ValueError as err:
            _LOGGER.warning("While processing state changes: %s", err)
        except DecimalException as err:
            _LOGGER.warning(
                "Invalid state (%s > %s): %s", old_state.state, new_state.state, err
            )
        self.async_write_ha_state()

    @callback
    def async_tariff_change(self, event):
        """Handle tariff changes."""
        new_state = event.data.get("new_state")
        if new_state is None:
            return

        self._change_status(new_state.state)

    def _change_status(self, tariff):
        if self._tariff == tariff:
            self._collecting = async_track_state_change_event(
                self.hass, [self._sensor_source_id], self.async_reading
            )
        else:
            if self._collecting:
                self._collecting()
            self._collecting = None

        _LOGGER.debug(
            "%s - %s - source <%s>",
            self._name,
            COLLECTING if self._collecting is not None else PAUSED,
            self._sensor_source_id,
        )

        self.async_write_ha_state()

    async def _async_reset_meter(self, event):
        """Determine cycle - Helper function for larger than daily cycles."""
        now = dt_util.now().date()
        if self._cron_pattern is not None:
            async_track_point_in_time(
                self.hass,
                self._async_reset_meter,
                croniter(self._cron_pattern, dt_util.now()).get_next(datetime),
            )
        elif (
            self._period == WEEKLY
            and now != now - timedelta(days=now.weekday()) + self._period_offset
        ):
            return
        elif (
            self._period == MONTHLY
            and now != date(now.year, now.month, 1) + self._period_offset
        ):
            return
        elif (
            self._period == BIMONTHLY
            and now
            != date(now.year, (((now.month - 1) // 2) * 2 + 1), 1) + self._period_offset
        ):
            return
        elif (
            self._period == QUARTERLY
            and now
            != date(now.year, (((now.month - 1) // 3) * 3 + 1), 1) + self._period_offset
        ):
            return
        elif (
            self._period == YEARLY and now != date(now.year, 1, 1) + self._period_offset
        ):
            return
        await self.async_reset_meter(self._tariff_entity)

    async def async_reset_meter(self, entity_id):
        """Reset meter."""
        if self._tariff_entity != entity_id:
            return
        _LOGGER.debug("Reset utility meter <%s>", self.entity_id)
        self._last_reset = dt_util.utcnow()
        self._last_period = str(self._state)
        self._state = 0
        self.async_write_ha_state()

    async def async_calibrate(self, value):
        """Calibrate the Utility Meter with a given value."""
        _LOGGER.debug("Calibrate %s = %s", self._name, value)
        self._state = value
        self.async_write_ha_state()

    async def async_added_to_hass(self):
        """Handle entity which will be added."""
        await super().async_added_to_hass()

        if self._cron_pattern is not None:
            async_track_point_in_time(
                self.hass,
                self._async_reset_meter,
                croniter(self._cron_pattern, dt_util.now()).get_next(datetime),
            )
        elif self._period == QUARTER_HOURLY:
            for quarter in range(4):
                async_track_time_change(
                    self.hass,
                    self._async_reset_meter,
                    minute=(quarter * 15)
                    + self._period_offset.seconds % (15 * 60) // 60,
                    second=self._period_offset.seconds % 60,
                )
        elif self._period == HOURLY:
            async_track_time_change(
                self.hass,
                self._async_reset_meter,
                minute=self._period_offset.seconds // 60,
                second=self._period_offset.seconds % 60,
            )
        elif self._period in [DAILY, WEEKLY, MONTHLY, BIMONTHLY, QUARTERLY, YEARLY]:
            async_track_time_change(
                self.hass,
                self._async_reset_meter,
                hour=self._period_offset.seconds // 3600,
                minute=self._period_offset.seconds % 3600 // 60,
                second=self._period_offset.seconds % 3600 % 60,
            )

        async_dispatcher_connect(self.hass, SIGNAL_RESET_METER, self.async_reset_meter)

        state = await self.async_get_last_state()
        if state:
            self._state = Decimal(state.state)
            self._unit_of_measurement = state.attributes.get(ATTR_UNIT_OF_MEASUREMENT)
            self._last_period = state.attributes.get(ATTR_LAST_PERIOD)
            self._last_reset = dt_util.as_utc(
                dt_util.parse_datetime(state.attributes.get(ATTR_LAST_RESET))
            )
            if state.attributes.get(ATTR_STATUS) == COLLECTING:
                # Fake cancellation function to init the meter in similar state
                self._collecting = lambda: None

        @callback
        def async_source_tracking(event):
            """Wait for source to be ready, then start meter."""
            if self._tariff_entity is not None:
                _LOGGER.debug(
                    "<%s> tracks utility meter %s", self.name, self._tariff_entity
                )
                async_track_state_change_event(
                    self.hass, [self._tariff_entity], self.async_tariff_change
                )

                tariff_entity_state = self.hass.states.get(self._tariff_entity)
                self._change_status(tariff_entity_state.state)
                return

            _LOGGER.debug("<%s> collecting from %s", self.name, self._sensor_source_id)
            self._collecting = async_track_state_change_event(
                self.hass, [self._sensor_source_id], self.async_reading
            )

        self.hass.bus.async_listen_once(
            EVENT_HOMEASSISTANT_START, async_source_tracking
        )

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

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

    @property
    def device_class(self):
        """Return the device class of the sensor."""
        return DEVICE_CLASS_MAP.get(self.unit_of_measurement)

    @property
    def state_class(self):
        """Return the device class of the sensor."""
        return (
            STATE_CLASS_MEASUREMENT
            if self._sensor_net_consumption
            else STATE_CLASS_TOTAL_INCREASING
        )

    @property
    def native_unit_of_measurement(self):
        """Return the unit the value is expressed in."""
        return self._unit_of_measurement

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

    @property
    def extra_state_attributes(self):
        """Return the state attributes of the sensor."""
        state_attr = {
            ATTR_SOURCE_ID: self._sensor_source_id,
            ATTR_STATUS: PAUSED if self._collecting is None else COLLECTING,
            ATTR_LAST_PERIOD: self._last_period,
        }
        if self._period is not None:
            state_attr[ATTR_PERIOD] = self._period
        if self._cron_pattern is not None:
            state_attr[ATTR_CRON_PATTERN] = self._cron_pattern
        if self._tariff is not None:
            state_attr[ATTR_TARIFF] = self._tariff
        return state_attr

    @property
    def icon(self):
        """Return the icon to use in the frontend, if any."""
        return ICON

    @property
    def last_reset(self):
        """Return the time when the sensor was last reset."""
        return self._last_reset