"""Support for Automation Device Specification (ADS)."""
import threading
import struct
import logging
import ctypes
from collections import namedtuple
import asyncio
import async_timeout

import voluptuous as vol

from homeassistant.const import (
    CONF_DEVICE,
    CONF_IP_ADDRESS,
    CONF_PORT,
    EVENT_HOMEASSISTANT_STOP,
)
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity

_LOGGER = logging.getLogger(__name__)

DATA_ADS = "data_ads"

# Supported Types
ADSTYPE_BOOL = "bool"
ADSTYPE_BYTE = "byte"
ADSTYPE_DINT = "dint"
ADSTYPE_INT = "int"
ADSTYPE_UDINT = "udint"
ADSTYPE_UINT = "uint"

CONF_ADS_FACTOR = "factor"
CONF_ADS_TYPE = "adstype"
CONF_ADS_VALUE = "value"
CONF_ADS_VAR = "adsvar"
CONF_ADS_VAR_BRIGHTNESS = "adsvar_brightness"
CONF_ADS_VAR_POSITION = "adsvar_position"

STATE_KEY_STATE = "state"
STATE_KEY_BRIGHTNESS = "brightness"
STATE_KEY_POSITION = "position"

DOMAIN = "ads"

SERVICE_WRITE_DATA_BY_NAME = "write_data_by_name"

CONFIG_SCHEMA = vol.Schema(
    {
        DOMAIN: vol.Schema(
            {
                vol.Required(CONF_DEVICE): cv.string,
                vol.Required(CONF_PORT): cv.port,
                vol.Optional(CONF_IP_ADDRESS): cv.string,
            }
        )
    },
    extra=vol.ALLOW_EXTRA,
)

SCHEMA_SERVICE_WRITE_DATA_BY_NAME = vol.Schema(
    {
        vol.Required(CONF_ADS_TYPE): vol.In(
            [
                ADSTYPE_INT,
                ADSTYPE_UINT,
                ADSTYPE_BYTE,
                ADSTYPE_BOOL,
                ADSTYPE_DINT,
                ADSTYPE_UDINT,
            ]
        ),
        vol.Required(CONF_ADS_VALUE): vol.Coerce(int),
        vol.Required(CONF_ADS_VAR): cv.string,
    }
)


def setup(hass, config):
    """Set up the ADS component."""
    import pyads

    conf = config[DOMAIN]

    net_id = conf.get(CONF_DEVICE)
    ip_address = conf.get(CONF_IP_ADDRESS)
    port = conf.get(CONF_PORT)

    client = pyads.Connection(net_id, port, ip_address)

    AdsHub.ADS_TYPEMAP = {
        ADSTYPE_BOOL: pyads.PLCTYPE_BOOL,
        ADSTYPE_BYTE: pyads.PLCTYPE_BYTE,
        ADSTYPE_DINT: pyads.PLCTYPE_DINT,
        ADSTYPE_INT: pyads.PLCTYPE_INT,
        ADSTYPE_UDINT: pyads.PLCTYPE_UDINT,
        ADSTYPE_UINT: pyads.PLCTYPE_UINT,
    }

    AdsHub.ADSError = pyads.ADSError
    AdsHub.PLCTYPE_BOOL = pyads.PLCTYPE_BOOL
    AdsHub.PLCTYPE_BYTE = pyads.PLCTYPE_BYTE
    AdsHub.PLCTYPE_DINT = pyads.PLCTYPE_DINT
    AdsHub.PLCTYPE_INT = pyads.PLCTYPE_INT
    AdsHub.PLCTYPE_UDINT = pyads.PLCTYPE_UDINT
    AdsHub.PLCTYPE_UINT = pyads.PLCTYPE_UINT

    try:
        ads = AdsHub(client)
    except pyads.ADSError:
        _LOGGER.error(
            "Could not connect to ADS host (netid=%s, ip=%s, port=%s)",
            net_id,
            ip_address,
            port,
        )
        return False

    hass.data[DATA_ADS] = ads
    hass.bus.listen(EVENT_HOMEASSISTANT_STOP, ads.shutdown)

    def handle_write_data_by_name(call):
        """Write a value to the connected ADS device."""
        ads_var = call.data.get(CONF_ADS_VAR)
        ads_type = call.data.get(CONF_ADS_TYPE)
        value = call.data.get(CONF_ADS_VALUE)

        try:
            ads.write_by_name(ads_var, value, ads.ADS_TYPEMAP[ads_type])
        except pyads.ADSError as err:
            _LOGGER.error(err)

    hass.services.register(
        DOMAIN,
        SERVICE_WRITE_DATA_BY_NAME,
        handle_write_data_by_name,
        schema=SCHEMA_SERVICE_WRITE_DATA_BY_NAME,
    )

    return True


# Tuple to hold data needed for notification
NotificationItem = namedtuple(
    "NotificationItem", "hnotify huser name plc_datatype callback"
)


class AdsHub:
    """Representation of an ADS connection."""

    def __init__(self, ads_client):
        """Initialize the ADS hub."""
        self._client = ads_client
        self._client.open()

        # All ADS devices are registered here
        self._devices = []
        self._notification_items = {}
        self._lock = threading.Lock()

    def shutdown(self, *args, **kwargs):
        """Shutdown ADS connection."""
        import pyads

        _LOGGER.debug("Shutting down ADS")
        for notification_item in self._notification_items.values():
            _LOGGER.debug(
                "Deleting device notification %d, %d",
                notification_item.hnotify,
                notification_item.huser,
            )
            try:
                self._client.del_device_notification(
                    notification_item.hnotify, notification_item.huser
                )
            except pyads.ADSError as err:
                _LOGGER.error(err)
        try:
            self._client.close()
        except pyads.ADSError as err:
            _LOGGER.error(err)

    def register_device(self, device):
        """Register a new device."""
        self._devices.append(device)

    def write_by_name(self, name, value, plc_datatype):
        """Write a value to the device."""
        import pyads

        with self._lock:
            try:
                return self._client.write_by_name(name, value, plc_datatype)
            except pyads.ADSError as err:
                _LOGGER.error("Error writing %s: %s", name, err)

    def read_by_name(self, name, plc_datatype):
        """Read a value from the device."""
        import pyads

        with self._lock:
            try:
                return self._client.read_by_name(name, plc_datatype)
            except pyads.ADSError as err:
                _LOGGER.error("Error reading %s: %s", name, err)

    def add_device_notification(self, name, plc_datatype, callback):
        """Add a notification to the ADS devices."""
        import pyads

        attr = pyads.NotificationAttrib(ctypes.sizeof(plc_datatype))

        with self._lock:
            try:
                hnotify, huser = self._client.add_device_notification(
                    name, attr, self._device_notification_callback
                )
            except pyads.ADSError as err:
                _LOGGER.error("Error subscribing to %s: %s", name, err)
            else:
                hnotify = int(hnotify)
                self._notification_items[hnotify] = NotificationItem(
                    hnotify, huser, name, plc_datatype, callback
                )

                _LOGGER.debug(
                    "Added device notification %d for variable %s", hnotify, name
                )

    def _device_notification_callback(self, notification, name):
        """Handle device notifications."""
        contents = notification.contents

        hnotify = int(contents.hNotification)
        _LOGGER.debug("Received notification %d", hnotify)
        data = contents.data

        try:
            with self._lock:
                notification_item = self._notification_items[hnotify]
        except KeyError:
            _LOGGER.error("Unknown device notification handle: %d", hnotify)
            return

        # Parse data to desired datatype
        if notification_item.plc_datatype == self.PLCTYPE_BOOL:
            value = bool(struct.unpack("<?", bytearray(data)[:1])[0])
        elif notification_item.plc_datatype == self.PLCTYPE_INT:
            value = struct.unpack("<h", bytearray(data)[:2])[0]
        elif notification_item.plc_datatype == self.PLCTYPE_BYTE:
            value = struct.unpack("<B", bytearray(data)[:1])[0]
        elif notification_item.plc_datatype == self.PLCTYPE_UINT:
            value = struct.unpack("<H", bytearray(data)[:2])[0]
        elif notification_item.plc_datatype == self.PLCTYPE_DINT:
            value = struct.unpack("<i", bytearray(data)[:4])[0]
        elif notification_item.plc_datatype == self.PLCTYPE_UDINT:
            value = struct.unpack("<I", bytearray(data)[:4])[0]
        else:
            value = bytearray(data)
            _LOGGER.warning("No callback available for this datatype")

        notification_item.callback(notification_item.name, value)


class AdsEntity(Entity):
    """Representation of ADS entity."""

    def __init__(self, ads_hub, name, ads_var):
        """Initialize ADS binary sensor."""
        self._name = name
        self._unique_id = ads_var
        self._state_dict = {}
        self._state_dict[STATE_KEY_STATE] = None
        self._ads_hub = ads_hub
        self._ads_var = ads_var
        self._event = None

    async def async_initialize_device(
        self, ads_var, plctype, state_key=STATE_KEY_STATE, factor=None
    ):
        """Register device notification."""

        def update(name, value):
            """Handle device notifications."""
            _LOGGER.debug("Variable %s changed its value to %d", name, value)

            if factor is None:
                self._state_dict[state_key] = value
            else:
                self._state_dict[state_key] = value / factor

            asyncio.run_coroutine_threadsafe(async_event_set(), self.hass.loop)
            self.schedule_update_ha_state()

        async def async_event_set():
            """Set event in async context."""
            self._event.set()

        self._event = asyncio.Event()

        await self.hass.async_add_executor_job(
            self._ads_hub.add_device_notification, ads_var, plctype, update
        )
        try:
            with async_timeout.timeout(10):
                await self._event.wait()
        except asyncio.TimeoutError:
            _LOGGER.debug("Variable %s: Timeout during first update", ads_var)

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

    @property
    def unique_id(self):
        """Return an unique identifier for this entity."""
        return self._unique_id

    @property
    def should_poll(self):
        """Return False because entity pushes its state to HA."""
        return False

    @property
    def available(self):
        """Return False if state has not been updated yet."""
        return self._state_dict[STATE_KEY_STATE] is not None