Component Automation - initial version

homeassistant/components/automation/state.py

@@ -0,0 +1,37 @@
+"""
+homeassistant.components.automation.state
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Offers state listening automation rules.
+"""
+import logging
+
+from homeassistant.const import MATCH_ALL
+
+
+CONF_ENTITY_ID = "state_entity_id"
+CONF_FROM = "state_from"
+CONF_TO = "state_to"
+
+
+def register(hass, config, action):
+    """ Listen for state changes based on `config`. """
+    entity_id = config.get(CONF_ENTITY_ID)
+
+    if entity_id is None:
+        logging.getLogger(__name__).error(
+            "Missing configuration key %s", CONF_ENTITY_ID)
+        return False
+
+    from_state = config.get(CONF_FROM, MATCH_ALL)
+    to_state = config.get(CONF_TO, MATCH_ALL)
+
+    # pylint: disable=unused-argument
+    def state_automation_listener(entity, from_s, to_s):
+        """ Listens for state changes and calls action. """
+        action()
+
+    hass.states.track_change(
+        entity_id, state_automation_listener, from_state, to_state)
+
+    return True