hass-core/homeassistant/components/automation/event.py

"""Offer event listening automation rules."""
import logging

import voluptuous as vol

from homeassistant.core import callback
from homeassistant.const import CONF_PLATFORM
from homeassistant.helpers import config_validation as cv

CONF_EVENT_TYPE = 'event_type'
CONF_EVENT_DATA = 'event_data'

_LOGGER = logging.getLogger(__name__)

TRIGGER_SCHEMA = vol.Schema({
    vol.Required(CONF_PLATFORM): 'event',
    vol.Required(CONF_EVENT_TYPE): cv.string,
    vol.Optional(CONF_EVENT_DATA): dict,
})


async def async_trigger(hass, config, action, automation_info):
    """Listen for events based on configuration."""
    event_type = config.get(CONF_EVENT_TYPE)
    event_data_schema = vol.Schema(
        config.get(CONF_EVENT_DATA),
        extra=vol.ALLOW_EXTRA) if config.get(CONF_EVENT_DATA) else None

    @callback
    def handle_event(event):
        """Listen for events and calls the action when data matches."""
        if event_data_schema:
            # Check that the event data matches the configured
            # schema if one was provided
            try:
                event_data_schema(event.data)
            except vol.Invalid:
                # If event data doesn't match requested schema, skip event
                return

        hass.async_run_job(action({
            'trigger': {
                'platform': 'event',
                'event': event,
            },
        }, context=event.context))

    return hass.bus.async_listen(event_type, handle_event)