"""Helper classes for Google Assistant integration."""
from asyncio import gather
from collections.abc import Mapping
from typing import List

from homeassistant.core import Context, callback
from homeassistant.const import (
    CONF_NAME,
    STATE_UNAVAILABLE,
    ATTR_SUPPORTED_FEATURES,
    ATTR_DEVICE_CLASS,
    CLOUD_NEVER_EXPOSED_ENTITIES,
)

from . import trait
from .const import (
    DOMAIN_TO_GOOGLE_TYPES,
    CONF_ALIASES,
    ERR_FUNCTION_NOT_SUPPORTED,
    DEVICE_CLASS_TO_GOOGLE_TYPES,
    CONF_ROOM_HINT,
)
from .error import SmartHomeError


class AbstractConfig:
    """Hold the configuration for Google Assistant."""

    @property
    def agent_user_id(self):
        """Return Agent User Id to use for query responses."""
        return None

    @property
    def entity_config(self):
        """Return entity config."""
        return {}

    @property
    def secure_devices_pin(self):
        """Return entity config."""
        return None

    def should_expose(self, state) -> bool:
        """Return if entity should be exposed."""
        raise NotImplementedError

    def should_2fa(self, state):
        """If an entity should have 2FA checked."""
        # pylint: disable=no-self-use
        return True


class RequestData:
    """Hold data associated with a particular request."""

    def __init__(self, config, user_id, request_id):
        """Initialize the request data."""
        self.config = config
        self.request_id = request_id
        self.context = Context(user_id=user_id)


def get_google_type(domain, device_class):
    """Google type based on domain and device class."""
    typ = DEVICE_CLASS_TO_GOOGLE_TYPES.get((domain, device_class))

    return typ if typ is not None else DOMAIN_TO_GOOGLE_TYPES[domain]


class GoogleEntity:
    """Adaptation of Entity expressed in Google's terms."""

    def __init__(self, hass, config, state):
        """Initialize a Google entity."""
        self.hass = hass
        self.config = config
        self.state = state
        self._traits = None

    @property
    def entity_id(self):
        """Return entity ID."""
        return self.state.entity_id

    @callback
    def traits(self):
        """Return traits for entity."""
        if self._traits is not None:
            return self._traits

        state = self.state
        domain = state.domain
        features = state.attributes.get(ATTR_SUPPORTED_FEATURES, 0)
        device_class = state.attributes.get(ATTR_DEVICE_CLASS)

        self._traits = [
            Trait(self.hass, state, self.config)
            for Trait in trait.TRAITS
            if Trait.supported(domain, features, device_class)
        ]
        return self._traits

    @callback
    def is_supported(self) -> bool:
        """Return if the entity is supported by Google."""
        return self.state.state != STATE_UNAVAILABLE and bool(self.traits())

    @callback
    def might_2fa(self) -> bool:
        """Return if the entity might encounter 2FA."""
        state = self.state
        domain = state.domain
        features = state.attributes.get(ATTR_SUPPORTED_FEATURES, 0)
        device_class = state.attributes.get(ATTR_DEVICE_CLASS)

        return any(
            trait.might_2fa(domain, features, device_class) for trait in self.traits()
        )

    async def sync_serialize(self):
        """Serialize entity for a SYNC response.

        https://developers.google.com/actions/smarthome/create-app#actiondevicessync
        """
        state = self.state

        entity_config = self.config.entity_config.get(state.entity_id, {})
        name = (entity_config.get(CONF_NAME) or state.name).strip()
        domain = state.domain
        device_class = state.attributes.get(ATTR_DEVICE_CLASS)

        traits = self.traits()

        device_type = get_google_type(domain, device_class)

        device = {
            "id": state.entity_id,
            "name": {"name": name},
            "attributes": {},
            "traits": [trait.name for trait in traits],
            "willReportState": False,
            "type": device_type,
        }

        # use aliases
        aliases = entity_config.get(CONF_ALIASES)
        if aliases:
            device["name"]["nicknames"] = aliases

        for trt in traits:
            device["attributes"].update(trt.sync_attributes())

        room = entity_config.get(CONF_ROOM_HINT)
        if room:
            device["roomHint"] = room
            return device

        dev_reg, ent_reg, area_reg = await gather(
            self.hass.helpers.device_registry.async_get_registry(),
            self.hass.helpers.entity_registry.async_get_registry(),
            self.hass.helpers.area_registry.async_get_registry(),
        )

        entity_entry = ent_reg.async_get(state.entity_id)
        if not (entity_entry and entity_entry.device_id):
            return device

        device_entry = dev_reg.devices.get(entity_entry.device_id)
        if not (device_entry and device_entry.area_id):
            return device

        area_entry = area_reg.areas.get(device_entry.area_id)
        if area_entry and area_entry.name:
            device["roomHint"] = area_entry.name

        return device

    @callback
    def query_serialize(self):
        """Serialize entity for a QUERY response.

        https://developers.google.com/actions/smarthome/create-app#actiondevicesquery
        """
        state = self.state

        if state.state == STATE_UNAVAILABLE:
            return {"online": False}

        attrs = {"online": True}

        for trt in self.traits():
            deep_update(attrs, trt.query_attributes())

        return attrs

    async def execute(self, data, command_payload):
        """Execute a command.

        https://developers.google.com/actions/smarthome/create-app#actiondevicesexecute
        """
        command = command_payload["command"]
        params = command_payload.get("params", {})
        challenge = command_payload.get("challenge", {})
        executed = False
        for trt in self.traits():
            if trt.can_execute(command, params):
                await trt.execute(command, data, params, challenge)
                executed = True
                break

        if not executed:
            raise SmartHomeError(
                ERR_FUNCTION_NOT_SUPPORTED,
                f"Unable to execute {command} for {self.state.entity_id}",
            )

    @callback
    def async_update(self):
        """Update the entity with latest info from Home Assistant."""
        self.state = self.hass.states.get(self.entity_id)

        if self._traits is None:
            return

        for trt in self._traits:
            trt.state = self.state


def deep_update(target, source):
    """Update a nested dictionary with another nested dictionary."""
    for key, value in source.items():
        if isinstance(value, Mapping):
            target[key] = deep_update(target.get(key, {}), value)
        else:
            target[key] = value
    return target


@callback
def async_get_entities(hass, config) -> List[GoogleEntity]:
    """Return all entities that are supported by Google."""
    entities = []
    for state in hass.states.async_all():
        if state.entity_id in CLOUD_NEVER_EXPOSED_ENTITIES:
            continue

        entity = GoogleEntity(hass, config, state)

        if entity.is_supported():
            entities.append(entity)

    return entities