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

"""
Offer event listening automation rules.

For more details about this automation rule, please refer to the documentation
at https://home-assistant.io/docs/automation/trigger/#event-trigger
"""
import asyncio
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, default={}): dict,
})


@asyncio.coroutine
def async_trigger(hass, config, action):
    """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)

    @callback
    def handle_event(event):
        """Listen for events and calls the action when data matches."""
        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,
            },
        })

    return hass.bus.async_listen(event_type, handle_event)