"""Alexa configuration for Home Assistant Cloud."""
import asyncio
from datetime import timedelta
import logging

import aiohttp
import async_timeout
from hass_nabucasa import cloud_api

from homeassistant.components.alexa import (
    config as alexa_config,
    entities as alexa_entities,
    errors as alexa_errors,
    state_report as alexa_state_report,
)
from homeassistant.const import CLOUD_NEVER_EXPOSED_ENTITIES
from homeassistant.core import callback
from homeassistant.helpers import entity_registry
from homeassistant.helpers.event import async_call_later
from homeassistant.util.dt import utcnow

from .const import (
    CONF_ENTITY_CONFIG,
    CONF_FILTER,
    DEFAULT_SHOULD_EXPOSE,
    PREF_SHOULD_EXPOSE,
    RequireRelink,
)

_LOGGER = logging.getLogger(__name__)

# Time to wait when entity preferences have changed before syncing it to
# the cloud.
SYNC_DELAY = 1


class AlexaConfig(alexa_config.AbstractConfig):
    """Alexa Configuration."""

    def __init__(self, hass, config, prefs, cloud):
        """Initialize the Alexa config."""
        super().__init__(hass)
        self._config = config
        self._prefs = prefs
        self._cloud = cloud
        self._token = None
        self._token_valid = None
        self._cur_entity_prefs = prefs.alexa_entity_configs
        self._alexa_sync_unsub = None
        self._endpoint = None

        prefs.async_listen_updates(self._async_prefs_updated)
        hass.bus.async_listen(
            entity_registry.EVENT_ENTITY_REGISTRY_UPDATED,
            self._handle_entity_registry_updated,
        )

    @property
    def enabled(self):
        """Return if Alexa is enabled."""
        return self._prefs.alexa_enabled

    @property
    def supports_auth(self):
        """Return if config supports auth."""
        return True

    @property
    def should_report_state(self):
        """Return if states should be proactively reported."""
        return self._prefs.alexa_report_state

    @property
    def endpoint(self):
        """Endpoint for report state."""
        if self._endpoint is None:
            raise ValueError("No endpoint available. Fetch access token first")

        return self._endpoint

    @property
    def locale(self):
        """Return config locale."""
        # Not clear how to determine locale atm.
        return "en-US"

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

    def should_expose(self, entity_id):
        """If an entity should be exposed."""
        if entity_id in CLOUD_NEVER_EXPOSED_ENTITIES:
            return False

        if not self._config[CONF_FILTER].empty_filter:
            return self._config[CONF_FILTER](entity_id)

        entity_configs = self._prefs.alexa_entity_configs
        entity_config = entity_configs.get(entity_id, {})
        return entity_config.get(PREF_SHOULD_EXPOSE, DEFAULT_SHOULD_EXPOSE)

    @callback
    def async_invalidate_access_token(self):
        """Invalidate access token."""
        self._token_valid = None

    async def async_get_access_token(self):
        """Get an access token."""
        if self._token_valid is not None and self._token_valid > utcnow():
            return self._token

        resp = await cloud_api.async_alexa_access_token(self._cloud)
        body = await resp.json()

        if resp.status == 400:
            if body["reason"] in ("RefreshTokenNotFound", "UnknownRegion"):
                if self.should_report_state:
                    await self._prefs.async_update(alexa_report_state=False)
                    self.hass.components.persistent_notification.async_create(
                        "There was an error reporting state to Alexa ({}). "
                        "Please re-link your Alexa skill via the Alexa app to "
                        "continue using it.".format(body["reason"]),
                        "Alexa state reporting disabled",
                        "cloud_alexa_report",
                    )
                raise RequireRelink

            raise alexa_errors.NoTokenAvailable

        self._token = body["access_token"]
        self._endpoint = body["event_endpoint"]
        self._token_valid = utcnow() + timedelta(seconds=body["expires_in"])
        return self._token

    async def _async_prefs_updated(self, prefs):
        """Handle updated preferences."""
        if self.should_report_state != self.is_reporting_states:
            if self.should_report_state:
                await self.async_enable_proactive_mode()
            else:
                await self.async_disable_proactive_mode()

            # State reporting is reported as a property on entities.
            # So when we change it, we need to sync all entities.
            await self.async_sync_entities()
            return

        # If entity prefs are the same or we have filter in config.yaml,
        # don't sync.
        if (
            self._cur_entity_prefs is prefs.alexa_entity_configs
            or not self._config[CONF_FILTER].empty_filter
        ):
            return

        if self._alexa_sync_unsub:
            self._alexa_sync_unsub()

        self._alexa_sync_unsub = async_call_later(
            self.hass, SYNC_DELAY, self._sync_prefs
        )

    async def _sync_prefs(self, _now):
        """Sync the updated preferences to Alexa."""
        self._alexa_sync_unsub = None
        old_prefs = self._cur_entity_prefs
        new_prefs = self._prefs.alexa_entity_configs

        seen = set()
        to_update = []
        to_remove = []

        for entity_id, info in old_prefs.items():
            seen.add(entity_id)
            old_expose = info.get(PREF_SHOULD_EXPOSE)

            if entity_id in new_prefs:
                new_expose = new_prefs[entity_id].get(PREF_SHOULD_EXPOSE)
            else:
                new_expose = None

            if old_expose == new_expose:
                continue

            if new_expose:
                to_update.append(entity_id)
            else:
                to_remove.append(entity_id)

        # Now all the ones that are in new prefs but never were in old prefs
        for entity_id, info in new_prefs.items():
            if entity_id in seen:
                continue

            new_expose = info.get(PREF_SHOULD_EXPOSE)

            if new_expose is None:
                continue

            # Only test if we should expose. It can never be a remove action,
            # as it didn't exist in old prefs object.
            if new_expose:
                to_update.append(entity_id)

        # We only set the prefs when update is successful, that way we will
        # retry when next change comes in.
        if await self._sync_helper(to_update, to_remove):
            self._cur_entity_prefs = new_prefs

    async def async_sync_entities(self):
        """Sync all entities to Alexa."""
        # Remove any pending sync
        if self._alexa_sync_unsub:
            self._alexa_sync_unsub()
            self._alexa_sync_unsub = None

        to_update = []
        to_remove = []

        for entity in alexa_entities.async_get_entities(self.hass, self):
            if self.should_expose(entity.entity_id):
                to_update.append(entity.entity_id)
            else:
                to_remove.append(entity.entity_id)

        return await self._sync_helper(to_update, to_remove)

    async def _sync_helper(self, to_update, to_remove) -> bool:
        """Sync entities to Alexa.

        Return boolean if it was successful.
        """
        if not to_update and not to_remove:
            return True

        # Make sure it's valid.
        await self.async_get_access_token()

        tasks = []

        if to_update:
            tasks.append(
                alexa_state_report.async_send_add_or_update_message(
                    self.hass, self, to_update
                )
            )

        if to_remove:
            tasks.append(
                alexa_state_report.async_send_delete_message(self.hass, self, to_remove)
            )

        try:
            with async_timeout.timeout(10):
                await asyncio.wait(tasks, return_when=asyncio.ALL_COMPLETED)

            return True

        except asyncio.TimeoutError:
            _LOGGER.warning("Timeout trying to sync entitites to Alexa")
            return False

        except aiohttp.ClientError as err:
            _LOGGER.warning("Error trying to sync entities to Alexa: %s", err)
            return False

    async def _handle_entity_registry_updated(self, event):
        """Handle when entity registry updated."""
        if not self.enabled or not self._cloud.is_logged_in:
            return

        action = event.data["action"]
        entity_id = event.data["entity_id"]
        to_update = []
        to_remove = []

        if action == "create" and self.should_expose(entity_id):
            to_update.append(entity_id)
        elif action == "remove" and self.should_expose(entity_id):
            to_remove.append(entity_id)

        try:
            await self._sync_helper(to_update, to_remove)
        except alexa_errors.NoTokenAvailable:
            pass