Reverse out change #14234 BOM Weather throttle fix (#17468)

* Reverse out change #14234 BOM Weather throttle fix

Reverted back to original throttle code to ensure sensors are updated on time.

* Fixed lint issues

* Review as a commit

* Use last_updated for attributes

* lint

* lint

homeassistant/components/sensor/bom.py

@@ -17,13 +17,13 @@ import zipfile
 import requests
 import voluptuous as vol
 
+import homeassistant.helpers.config_validation as cv
 from homeassistant.components.sensor import PLATFORM_SCHEMA
 from homeassistant.const import (
     CONF_MONITORED_CONDITIONS, TEMP_CELSIUS, CONF_NAME, ATTR_ATTRIBUTION,
     CONF_LATITUDE, CONF_LONGITUDE)
 from homeassistant.helpers.entity import Entity
 from homeassistant.util import Throttle
-import homeassistant.helpers.config_validation as cv
 
 _RESOURCE = 'http://www.bom.gov.au/fwo/{}/{}.{}.json'
 _LOGGER = logging.getLogger(__name__)
@@ -39,7 +39,7 @@ CONF_STATION = 'station'
 CONF_ZONE_ID = 'zone_id'
 CONF_WMO_ID = 'wmo_id'
 
-MIN_TIME_BETWEEN_UPDATES = datetime.timedelta(minutes=35)
+MIN_TIME_BETWEEN_UPDATES = datetime.timedelta(seconds=60)
 
 SENSOR_TYPES = {
     'wmo': ['wmo', None],
@@ -159,9 +159,7 @@ class BOMCurrentSensor(Entity):
         """Return the state attributes of the device."""
         attr = {
             ATTR_ATTRIBUTION: CONF_ATTRIBUTION,
-            ATTR_LAST_UPDATE: datetime.datetime.strptime(
-                str(self.bom_data.latest_data['local_date_time_full']),
-                '%Y%m%d%H%M%S'),
+            ATTR_LAST_UPDATE: self.bom_data.last_updated,
             ATTR_SENSOR_ID: self._condition,
             ATTR_STATION_ID: self.bom_data.latest_data['wmo'],
             ATTR_STATION_NAME: self.bom_data.latest_data['name'],
@@ -188,6 +186,7 @@ class BOMCurrentData:
         self._hass = hass
         self._zone_id, self._wmo_id = station_id.split('.')
         self._data = None
+        self.last_updated = None
 
     def _build_url(self):
         """Build the URL for the requests."""
@@ -211,17 +210,50 @@ class BOMCurrentData:
         for the latest value that is not `-`.
 
         Iterators are used in this method to avoid iterating needlessly
-        iterating through the entire BOM provided dataset.
+        through the entire BOM provided dataset.
         """
         condition_readings = (entry[condition] for entry in self._data)
         return next((x for x in condition_readings if x != '-'), None)
 
+    def should_update(self):
+        """Determine whether an update should occur.
+
+        BOM provides updated data every 30 minutes. We manually define
+        refreshing logic here rather than a throttle to keep updates
+        in lock-step with BOM.
+
+        If 35 minutes has passed since the last BOM data update, then
+        an update should be done.
+        """
+        if self.last_updated is None:
+            # Never updated before, therefore an update should occur.
+            return True
+
+        now = datetime.datetime.now()
+        update_due_at = self.last_updated + datetime.timedelta(minutes=35)
+        return now > update_due_at
+
     @Throttle(MIN_TIME_BETWEEN_UPDATES)
     def update(self):
         """Get the latest data from BOM."""
+        if not self.should_update():
+            _LOGGER.debug(
+                "BOM was updated %s minutes ago, skipping update as"
+                " < 35 minutes, Now: %s, LastUpdate: %s",
+                (datetime.datetime.now() - self.last_updated),
+                datetime.datetime.now(), self.last_updated)
+            return
+
         try:
             result = requests.get(self._build_url(), timeout=10).json()
             self._data = result['observations']['data']
+
+            # set lastupdate using self._data[0] as the first element in the
+            # array is the latest date in the json
+            self.last_updated = datetime.datetime.strptime(
+                str(self._data[0]['local_date_time_full']), '%Y%m%d%H%M%S')
+            return
+
         except ValueError as err:
             _LOGGER.error("Check BOM %s", err.args)
             self._data = None