""" Service to increase/decrease light brightness"""
import logging
import voluptuous as vol

from homeassistant.components.light import ATTR_BRIGHTNESS, DOMAIN as LIGHT_DOMAIN, ATTR_TRANSITION
from homeassistant.const import SERVICE_TURN_ON, ATTR_ENTITY_ID

# The domain of your component. Should be equal to the name of your component.
from homeassistant.helpers.service import async_extract_entity_ids

DOMAIN = "dimmer"

# List of component names (string) your component depends upon.
# We depend on group because group will be loaded after all the components that
# initialize devices have been setup.
DEPENDENCIES = ['group', 'light']

# Name of the service that we expose.
SERVICE_DIM = 'dim'

# Shortcut for the logger
_LOGGER = logging.getLogger(__name__)

# Validate that all required config options are given.
CONFIG_SCHEMA = vol.Schema({
    DOMAIN: vol.Schema({})
}, extra=vol.ALLOW_EXTRA)


async def async_setup(hass, config):
    """Setup example component."""

    async def async_dim_service(service):
        params = service.data.copy()

        entity_ids = await async_extract_entity_ids(hass, service, expand_group=True)

        offset = params.get('offset', None)
        factor = params.get('factor', None)
        min_brightness = params.get('min_brightness', 6)

        transition = params.get(ATTR_TRANSITION, None)

        if factor is None and offset is None:
            offset = 50

        assert not (factor is not None and offset is not None)

        def clip_value(level):
            level = int(level)
            if level < min_brightness:
                return min_brightness
            if level > 255:
                return 255
            return level

        for entity_id in entity_ids:
            brightness = hass.states.get(entity_id).attributes.get('brightness', 0)
            if factor is not None:
                data = {ATTR_BRIGHTNESS: clip_value(brightness * factor)}
            if offset is not None:
                data = {ATTR_BRIGHTNESS: clip_value(brightness + offset)}
            data[ATTR_ENTITY_ID] = entity_id
            if transition:
                data[ATTR_TRANSITION] = transition
            await hass.services.async_call(LIGHT_DOMAIN, SERVICE_TURN_ON, data)

    hass.services.async_register(DOMAIN, SERVICE_DIM, async_dim_service)

    return True