"""Support for Template lights."""
import logging

import voluptuous as vol

from homeassistant.components.light import (
    ATTR_BRIGHTNESS,
    ENTITY_ID_FORMAT,
    SUPPORT_BRIGHTNESS,
    Light,
)
from homeassistant.const import (
    CONF_ENTITY_ID,
    CONF_ENTITY_PICTURE_TEMPLATE,
    CONF_FRIENDLY_NAME,
    CONF_ICON_TEMPLATE,
    CONF_LIGHTS,
    CONF_VALUE_TEMPLATE,
    EVENT_HOMEASSISTANT_START,
    STATE_OFF,
    STATE_ON,
)
from homeassistant.core import callback
from homeassistant.exceptions import TemplateError
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.config_validation import PLATFORM_SCHEMA
from homeassistant.helpers.entity import async_generate_entity_id
from homeassistant.helpers.event import async_track_state_change
from homeassistant.helpers.script import Script

from . import extract_entities, initialise_templates
from .const import CONF_AVAILABILITY_TEMPLATE

_LOGGER = logging.getLogger(__name__)
_VALID_STATES = [STATE_ON, STATE_OFF, "true", "false"]

CONF_ON_ACTION = "turn_on"
CONF_OFF_ACTION = "turn_off"
CONF_LEVEL_ACTION = "set_level"
CONF_LEVEL_TEMPLATE = "level_template"

LIGHT_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_ON_ACTION): cv.SCRIPT_SCHEMA,
        vol.Required(CONF_OFF_ACTION): cv.SCRIPT_SCHEMA,
        vol.Optional(CONF_VALUE_TEMPLATE): cv.template,
        vol.Optional(CONF_ICON_TEMPLATE): cv.template,
        vol.Optional(CONF_ENTITY_PICTURE_TEMPLATE): cv.template,
        vol.Optional(CONF_AVAILABILITY_TEMPLATE): cv.template,
        vol.Optional(CONF_LEVEL_ACTION): cv.SCRIPT_SCHEMA,
        vol.Optional(CONF_LEVEL_TEMPLATE): cv.template,
        vol.Optional(CONF_FRIENDLY_NAME): cv.string,
        vol.Optional(CONF_ENTITY_ID): cv.entity_ids,
    }
)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {vol.Required(CONF_LIGHTS): cv.schema_with_slug_keys(LIGHT_SCHEMA)}
)


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up the Template Lights."""
    lights = []

    for device, device_config in config[CONF_LIGHTS].items():
        friendly_name = device_config.get(CONF_FRIENDLY_NAME, device)

        state_template = device_config.get(CONF_VALUE_TEMPLATE)
        icon_template = device_config.get(CONF_ICON_TEMPLATE)
        entity_picture_template = device_config.get(CONF_ENTITY_PICTURE_TEMPLATE)
        availability_template = device_config.get(CONF_AVAILABILITY_TEMPLATE)
        level_template = device_config.get(CONF_LEVEL_TEMPLATE)

        on_action = device_config[CONF_ON_ACTION]
        off_action = device_config[CONF_OFF_ACTION]
        level_action = device_config.get(CONF_LEVEL_ACTION)

        templates = {
            CONF_VALUE_TEMPLATE: state_template,
            CONF_ICON_TEMPLATE: icon_template,
            CONF_ENTITY_PICTURE_TEMPLATE: entity_picture_template,
            CONF_AVAILABILITY_TEMPLATE: availability_template,
            CONF_LEVEL_TEMPLATE: level_template,
        }

        initialise_templates(hass, templates)
        entity_ids = extract_entities(device, "light", None, templates)

        lights.append(
            LightTemplate(
                hass,
                device,
                friendly_name,
                state_template,
                icon_template,
                entity_picture_template,
                availability_template,
                on_action,
                off_action,
                level_action,
                level_template,
                entity_ids,
            )
        )

    if not lights:
        _LOGGER.error("No lights added")
        return False

    async_add_entities(lights)
    return True


class LightTemplate(Light):
    """Representation of a templated Light, including dimmable."""

    def __init__(
        self,
        hass,
        device_id,
        friendly_name,
        state_template,
        icon_template,
        entity_picture_template,
        availability_template,
        on_action,
        off_action,
        level_action,
        level_template,
        entity_ids,
    ):
        """Initialize the light."""
        self.hass = hass
        self.entity_id = async_generate_entity_id(
            ENTITY_ID_FORMAT, device_id, hass=hass
        )
        self._name = friendly_name
        self._template = state_template
        self._icon_template = icon_template
        self._entity_picture_template = entity_picture_template
        self._availability_template = availability_template
        self._on_script = Script(hass, on_action)
        self._off_script = Script(hass, off_action)
        self._level_script = None
        if level_action is not None:
            self._level_script = Script(hass, level_action)
        self._level_template = level_template

        self._state = False
        self._icon = None
        self._entity_picture = None
        self._brightness = None
        self._entities = entity_ids
        self._available = True

        if self._template is not None:
            self._template.hass = self.hass
        if self._level_template is not None:
            self._level_template.hass = self.hass
        if self._icon_template is not None:
            self._icon_template.hass = self.hass
        if self._entity_picture_template is not None:
            self._entity_picture_template.hass = self.hass
        if self._availability_template is not None:
            self._availability_template.hass = self.hass

    @property
    def brightness(self):
        """Return the brightness of the light."""
        return self._brightness

    @property
    def name(self):
        """Return the display name of this light."""
        return self._name

    @property
    def supported_features(self):
        """Flag supported features."""
        if self._level_script is not None:
            return SUPPORT_BRIGHTNESS

        return 0

    @property
    def is_on(self):
        """Return true if device is on."""
        return self._state

    @property
    def should_poll(self):
        """Return the polling state."""
        return False

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

    @property
    def entity_picture(self):
        """Return the entity picture to use in the frontend, if any."""
        return self._entity_picture

    @property
    def available(self) -> bool:
        """Return if the device is available."""
        return self._available

    async def async_added_to_hass(self):
        """Register callbacks."""

        @callback
        def template_light_state_listener(entity, old_state, new_state):
            """Handle target device state changes."""
            self.async_schedule_update_ha_state(True)

        @callback
        def template_light_startup(event):
            """Update template on startup."""
            if (
                self._template is not None
                or self._level_template is not None
                or self._availability_template is not None
            ):
                async_track_state_change(
                    self.hass, self._entities, template_light_state_listener
                )

            self.async_schedule_update_ha_state(True)

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

    async def async_turn_on(self, **kwargs):
        """Turn the light on."""
        optimistic_set = False
        # set optimistic states
        if self._template is None:
            self._state = True
            optimistic_set = True

        if self._level_template is None and ATTR_BRIGHTNESS in kwargs:
            _LOGGER.info(
                "Optimistically setting brightness to %s", kwargs[ATTR_BRIGHTNESS]
            )
            self._brightness = kwargs[ATTR_BRIGHTNESS]
            optimistic_set = True

        if ATTR_BRIGHTNESS in kwargs and self._level_script:
            await self._level_script.async_run(
                {"brightness": kwargs[ATTR_BRIGHTNESS]}, context=self._context
            )
        else:
            await self._on_script.async_run()

        if optimistic_set:
            self.async_schedule_update_ha_state()

    async def async_turn_off(self, **kwargs):
        """Turn the light off."""
        await self._off_script.async_run(context=self._context)
        if self._template is None:
            self._state = False
            self.async_schedule_update_ha_state()

    async def async_update(self):
        """Update the state from the template."""
        if self._template is not None:
            try:
                state = self._template.async_render().lower()
            except TemplateError as ex:
                _LOGGER.error(ex)
                self._state = None

            if state in _VALID_STATES:
                self._state = state in ("true", STATE_ON)
            else:
                _LOGGER.error(
                    "Received invalid light is_on state: %s. Expected: %s",
                    state,
                    ", ".join(_VALID_STATES),
                )
                self._state = None

        if self._level_template is not None:
            try:
                brightness = self._level_template.async_render()
            except TemplateError as ex:
                _LOGGER.error(ex)
                self._state = None

            if 0 <= int(brightness) <= 255:
                self._brightness = int(brightness)
            else:
                _LOGGER.error(
                    "Received invalid brightness : %s. Expected: 0-255", brightness
                )
                self._brightness = None

        for property_name, template in (
            ("_icon", self._icon_template),
            ("_entity_picture", self._entity_picture_template),
            ("_available", self._availability_template),
        ):
            if template is None:
                continue

            try:
                value = template.async_render()
                if property_name == "_available":
                    value = value.lower() == "true"
                setattr(self, property_name, value)
            except TemplateError as ex:
                friendly_property_name = property_name[1:].replace("_", " ")
                if ex.args and ex.args[0].startswith(
                    "UndefinedError: 'None' has no attribute"
                ):
                    # Common during HA startup - so just a warning
                    _LOGGER.warning(
                        "Could not render %s template %s," " the state is unknown.",
                        friendly_property_name,
                        self._name,
                    )
                    return

                try:
                    setattr(self, property_name, getattr(super(), property_name))
                except AttributeError:
                    _LOGGER.error(
                        "Could not render %s template %s: %s",
                        friendly_property_name,
                        self._name,
                        ex,
                    )
