"""Support for tracking people."""
from collections import OrderedDict
from itertools import chain
import logging
from typing import Optional
import uuid

import voluptuous as vol

from homeassistant.auth import EVENT_USER_REMOVED
from homeassistant.components import websocket_api
from homeassistant.components.device_tracker import (
    ATTR_SOURCE_TYPE,
    DOMAIN as DEVICE_TRACKER_DOMAIN,
    SOURCE_TYPE_GPS,
)
from homeassistant.const import (
    ATTR_GPS_ACCURACY,
    ATTR_ID,
    ATTR_LATITUDE,
    ATTR_LONGITUDE,
    CONF_ID,
    CONF_NAME,
    EVENT_HOMEASSISTANT_START,
    STATE_HOME,
    STATE_NOT_HOME,
    STATE_UNAVAILABLE,
    STATE_UNKNOWN,
)
from homeassistant.core import Event, State, callback
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity_component import EntityComponent
from homeassistant.helpers.event import async_track_state_change
from homeassistant.helpers.restore_state import RestoreEntity
from homeassistant.helpers.storage import Store
from homeassistant.helpers.typing import ConfigType, HomeAssistantType
from homeassistant.loader import bind_hass

_LOGGER = logging.getLogger(__name__)

ATTR_EDITABLE = "editable"
ATTR_SOURCE = "source"
ATTR_USER_ID = "user_id"

CONF_DEVICE_TRACKERS = "device_trackers"
CONF_USER_ID = "user_id"

DOMAIN = "person"

STORAGE_KEY = DOMAIN
STORAGE_VERSION = 1
SAVE_DELAY = 10
# Device tracker states to ignore
IGNORE_STATES = (STATE_UNKNOWN, STATE_UNAVAILABLE)

PERSON_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_ID): cv.string,
        vol.Required(CONF_NAME): cv.string,
        vol.Optional(CONF_USER_ID): cv.string,
        vol.Optional(CONF_DEVICE_TRACKERS, default=[]): vol.All(
            cv.ensure_list, cv.entities_domain(DEVICE_TRACKER_DOMAIN)
        ),
    }
)

CONFIG_SCHEMA = vol.Schema(
    {vol.Optional(DOMAIN): vol.All(cv.ensure_list, cv.remove_falsy, [PERSON_SCHEMA])},
    extra=vol.ALLOW_EXTRA,
)

_UNDEF = object()


@bind_hass
async def async_create_person(hass, name, *, user_id=None, device_trackers=None):
    """Create a new person."""
    await hass.data[DOMAIN].async_create_person(
        name=name, user_id=user_id, device_trackers=device_trackers
    )


class PersonManager:
    """Manage person data."""

    def __init__(
        self, hass: HomeAssistantType, component: EntityComponent, config_persons
    ):
        """Initialize person storage."""
        self.hass = hass
        self.component = component
        self.store = Store(hass, STORAGE_VERSION, STORAGE_KEY)
        self.storage_data = None

        config_data = self.config_data = OrderedDict()
        for conf in config_persons:
            person_id = conf[CONF_ID]

            if person_id in config_data:
                _LOGGER.error("Found config user with duplicate ID: %s", person_id)
                continue

            config_data[person_id] = conf

    @property
    def storage_persons(self):
        """Iterate over persons stored in storage."""
        return list(self.storage_data.values())

    @property
    def config_persons(self):
        """Iterate over persons stored in config."""
        return list(self.config_data.values())

    async def async_initialize(self):
        """Get the person data."""
        raw_storage = await self.store.async_load()

        if raw_storage is None:
            raw_storage = {"persons": []}

        storage_data = self.storage_data = OrderedDict()

        for person in raw_storage["persons"]:
            storage_data[person[CONF_ID]] = person

        entities = []
        seen_users = set()

        for person_conf in self.config_data.values():
            person_id = person_conf[CONF_ID]
            user_id = person_conf.get(CONF_USER_ID)

            if user_id is not None:
                if await self.hass.auth.async_get_user(user_id) is None:
                    _LOGGER.error("Invalid user_id detected for person %s", person_id)
                    continue

                if user_id in seen_users:
                    _LOGGER.error(
                        "Duplicate user_id %s detected for person %s",
                        user_id,
                        person_id,
                    )
                    continue

                seen_users.add(user_id)

            entities.append(Person(person_conf, False))

        # To make sure IDs don't overlap between config/storage
        seen_persons = set(self.config_data)

        for person_conf in storage_data.values():
            person_id = person_conf[CONF_ID]
            user_id = person_conf[CONF_USER_ID]

            if person_id in seen_persons:
                _LOGGER.error(
                    "Skipping adding person from storage with same ID as"
                    " configuration.yaml entry: %s",
                    person_id,
                )
                continue

            if user_id is not None and user_id in seen_users:
                _LOGGER.error(
                    "Duplicate user_id %s detected for person %s", user_id, person_id
                )
                continue

            # To make sure all users have just 1 person linked.
            seen_users.add(user_id)

            entities.append(Person(person_conf, True))

        if entities:
            await self.component.async_add_entities(entities)

        self.hass.bus.async_listen(EVENT_USER_REMOVED, self._user_removed)

    async def async_create_person(self, *, name, device_trackers=None, user_id=None):
        """Create a new person."""
        if not name:
            raise ValueError("Name is required")

        if user_id is not None:
            await self._validate_user_id(user_id)

        person = {
            CONF_ID: uuid.uuid4().hex,
            CONF_NAME: name,
            CONF_USER_ID: user_id,
            CONF_DEVICE_TRACKERS: device_trackers or [],
        }
        self.storage_data[person[CONF_ID]] = person
        self._async_schedule_save()
        await self.component.async_add_entities([Person(person, True)])
        return person

    async def async_update_person(
        self, person_id, *, name=_UNDEF, device_trackers=_UNDEF, user_id=_UNDEF
    ):
        """Update person."""
        current = self.storage_data.get(person_id)

        if current is None:
            raise ValueError("Invalid person specified.")

        changes = {
            key: value
            for key, value in (
                (CONF_NAME, name),
                (CONF_DEVICE_TRACKERS, device_trackers),
                (CONF_USER_ID, user_id),
            )
            if value is not _UNDEF and current[key] != value
        }

        if CONF_USER_ID in changes and user_id is not None:
            await self._validate_user_id(user_id)

        self.storage_data[person_id].update(changes)
        self._async_schedule_save()

        for entity in self.component.entities:
            if entity.unique_id == person_id:
                entity.person_updated()
                break

        return self.storage_data[person_id]

    async def async_delete_person(self, person_id):
        """Delete person."""
        if person_id not in self.storage_data:
            raise ValueError("Invalid person specified.")

        self.storage_data.pop(person_id)
        self._async_schedule_save()
        ent_reg = await self.hass.helpers.entity_registry.async_get_registry()

        for entity in self.component.entities:
            if entity.unique_id == person_id:
                await entity.async_remove()
                ent_reg.async_remove(entity.entity_id)
                break

    @callback
    def _async_schedule_save(self) -> None:
        """Schedule saving the area registry."""
        self.store.async_delay_save(self._data_to_save, SAVE_DELAY)

    @callback
    def _data_to_save(self) -> dict:
        """Return data of area registry to store in a file."""
        return {"persons": list(self.storage_data.values())}

    async def _validate_user_id(self, user_id):
        """Validate the used user_id."""
        if await self.hass.auth.async_get_user(user_id) is None:
            raise ValueError("User does not exist")

        if any(
            person
            for person in chain(self.storage_data.values(), self.config_data.values())
            if person.get(CONF_USER_ID) == user_id
        ):
            raise ValueError("User already taken")

    async def _user_removed(self, event: Event):
        """Handle event that a person is removed."""
        user_id = event.data["user_id"]
        for person in self.storage_data.values():
            if person[CONF_USER_ID] == user_id:
                await self.async_update_person(person_id=person[CONF_ID], user_id=None)


async def async_setup(hass: HomeAssistantType, config: ConfigType):
    """Set up the person component."""
    component = EntityComponent(_LOGGER, DOMAIN, hass)
    conf_persons = config.get(DOMAIN, [])
    manager = hass.data[DOMAIN] = PersonManager(hass, component, conf_persons)
    await manager.async_initialize()

    websocket_api.async_register_command(hass, ws_list_person)
    websocket_api.async_register_command(hass, ws_create_person)
    websocket_api.async_register_command(hass, ws_update_person)
    websocket_api.async_register_command(hass, ws_delete_person)

    return True


class Person(RestoreEntity):
    """Represent a tracked person."""

    def __init__(self, config, editable):
        """Set up person."""
        self._config = config
        self._editable = editable
        self._latitude = None
        self._longitude = None
        self._gps_accuracy = None
        self._source = None
        self._state = None
        self._unsub_track_device = None

    @property
    def name(self):
        """Return the name of the entity."""
        return self._config[CONF_NAME]

    @property
    def should_poll(self):
        """Return True if entity has to be polled for state.

        False if entity pushes its state to HA.
        """
        return False

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

    @property
    def state_attributes(self):
        """Return the state attributes of the person."""
        data = {ATTR_EDITABLE: self._editable, ATTR_ID: self.unique_id}
        if self._latitude is not None:
            data[ATTR_LATITUDE] = self._latitude
        if self._longitude is not None:
            data[ATTR_LONGITUDE] = self._longitude
        if self._gps_accuracy is not None:
            data[ATTR_GPS_ACCURACY] = self._gps_accuracy
        if self._source is not None:
            data[ATTR_SOURCE] = self._source
        user_id = self._config.get(CONF_USER_ID)
        if user_id is not None:
            data[ATTR_USER_ID] = user_id
        return data

    @property
    def unique_id(self):
        """Return a unique ID for the person."""
        return self._config[CONF_ID]

    async def async_added_to_hass(self):
        """Register device trackers."""
        await super().async_added_to_hass()
        state = await self.async_get_last_state()
        if state:
            self._parse_source_state(state)

        if self.hass.is_running:
            # Update person now if hass is already running.
            self.person_updated()
        else:
            # Wait for hass start to not have race between person
            # and device trackers finishing setup.
            @callback
            def person_start_hass(now):
                self.person_updated()

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

    @callback
    def person_updated(self):
        """Handle when the config is updated."""
        if self._unsub_track_device is not None:
            self._unsub_track_device()
            self._unsub_track_device = None

        trackers = self._config.get(CONF_DEVICE_TRACKERS)

        if trackers:
            _LOGGER.debug("Subscribe to device trackers for %s", self.entity_id)

            self._unsub_track_device = async_track_state_change(
                self.hass, trackers, self._async_handle_tracker_update
            )

        self._update_state()

    @callback
    def _async_handle_tracker_update(self, entity, old_state, new_state):
        """Handle the device tracker state changes."""
        self._update_state()

    @callback
    def _update_state(self):
        """Update the state."""
        latest_non_gps_home = latest_not_home = latest_gps = latest = None
        for entity_id in self._config.get(CONF_DEVICE_TRACKERS, []):
            state = self.hass.states.get(entity_id)

            if not state or state.state in IGNORE_STATES:
                continue

            if state.attributes.get(ATTR_SOURCE_TYPE) == SOURCE_TYPE_GPS:
                latest_gps = _get_latest(latest_gps, state)
            elif state.state == STATE_HOME:
                latest_non_gps_home = _get_latest(latest_non_gps_home, state)
            elif state.state == STATE_NOT_HOME:
                latest_not_home = _get_latest(latest_not_home, state)

        if latest_non_gps_home:
            latest = latest_non_gps_home
        elif latest_gps:
            latest = latest_gps
        else:
            latest = latest_not_home

        if latest:
            self._parse_source_state(latest)
        else:
            self._state = None
            self._source = None
            self._latitude = None
            self._longitude = None
            self._gps_accuracy = None

        self.async_schedule_update_ha_state()

    @callback
    def _parse_source_state(self, state):
        """Parse source state and set person attributes.

        This is a device tracker state or the restored person state.
        """
        self._state = state.state
        self._source = state.entity_id
        self._latitude = state.attributes.get(ATTR_LATITUDE)
        self._longitude = state.attributes.get(ATTR_LONGITUDE)
        self._gps_accuracy = state.attributes.get(ATTR_GPS_ACCURACY)


@websocket_api.websocket_command({vol.Required("type"): "person/list"})
def ws_list_person(
    hass: HomeAssistantType, connection: websocket_api.ActiveConnection, msg
):
    """List persons."""
    manager: PersonManager = hass.data[DOMAIN]
    connection.send_result(
        msg["id"],
        {"storage": manager.storage_persons, "config": manager.config_persons},
    )


@websocket_api.websocket_command(
    {
        vol.Required("type"): "person/create",
        vol.Required("name"): vol.All(str, vol.Length(min=1)),
        vol.Optional("user_id"): vol.Any(str, None),
        vol.Optional("device_trackers", default=[]): vol.All(
            cv.ensure_list, cv.entities_domain(DEVICE_TRACKER_DOMAIN)
        ),
    }
)
@websocket_api.require_admin
@websocket_api.async_response
async def ws_create_person(
    hass: HomeAssistantType, connection: websocket_api.ActiveConnection, msg
):
    """Create a person."""
    manager: PersonManager = hass.data[DOMAIN]
    try:
        person = await manager.async_create_person(
            name=msg["name"],
            user_id=msg.get("user_id"),
            device_trackers=msg["device_trackers"],
        )
        connection.send_result(msg["id"], person)
    except ValueError as err:
        connection.send_error(
            msg["id"], websocket_api.const.ERR_INVALID_FORMAT, str(err)
        )


@websocket_api.websocket_command(
    {
        vol.Required("type"): "person/update",
        vol.Required("person_id"): str,
        vol.Required("name"): vol.All(str, vol.Length(min=1)),
        vol.Optional("user_id"): vol.Any(str, None),
        vol.Optional(CONF_DEVICE_TRACKERS, default=[]): vol.All(
            cv.ensure_list, cv.entities_domain(DEVICE_TRACKER_DOMAIN)
        ),
    }
)
@websocket_api.require_admin
@websocket_api.async_response
async def ws_update_person(
    hass: HomeAssistantType, connection: websocket_api.ActiveConnection, msg
):
    """Update a person."""
    manager: PersonManager = hass.data[DOMAIN]
    changes = {}
    for key in ("name", "user_id", "device_trackers"):
        if key in msg:
            changes[key] = msg[key]

    try:
        person = await manager.async_update_person(msg["person_id"], **changes)
        connection.send_result(msg["id"], person)
    except ValueError as err:
        connection.send_error(
            msg["id"], websocket_api.const.ERR_INVALID_FORMAT, str(err)
        )


@websocket_api.websocket_command(
    {vol.Required("type"): "person/delete", vol.Required("person_id"): str}
)
@websocket_api.require_admin
@websocket_api.async_response
async def ws_delete_person(
    hass: HomeAssistantType, connection: websocket_api.ActiveConnection, msg
):
    """Delete a person."""
    manager: PersonManager = hass.data[DOMAIN]
    await manager.async_delete_person(msg["person_id"])
    connection.send_result(msg["id"])


def _get_latest(prev: Optional[State], curr: State):
    """Get latest state."""
    if prev is None or curr.last_updated > prev.last_updated:
        return curr
    return prev