implement get_significant_states

This adds a new function to history module which returns significant
states. For most domains this is the list of state changes. For the
thermostat domain this also includes attribute changes, so that
changes in the current_temperature are exposed to the graphing layer.

Closes #881

homeassistant/components/history.py

@@ -18,6 +18,8 @@ from homeassistant.const import HTTP_BAD_REQUEST
 DOMAIN = 'history'
 DEPENDENCIES = ['recorder', 'http']
 
+SIGNIFICANT_DOMAINS = ('thermostat',)
+
 URL_HISTORY_PERIOD = re.compile(
     r'/api/history/period(?:/(?P<date>\d{4}-\d{1,2}-\d{1,2})|)')
 
@@ -35,6 +37,37 @@ def last_5_states(entity_id):
     return recorder.query_states(query, (entity_id, ))
 
 
+def get_significant_states(start_time, end_time=None, entity_id=None):
+    """Return states changes during UTC period start_time - end_time.
+
+    Significant states are all states where there is a state change,
+    as well as all states from certain domains (for instance
+    thermostat so that we get current temperature in our graphs).
+
+    """
+    where = """
+        (domain in ({}) or last_changed=last_updated)
+        AND last_updated > ?
+    """.format(",".join(["'%s'" % x for x in SIGNIFICANT_DOMAINS]))
+
+    data = [start_time]
+
+    if end_time is not None:
+        where += "AND last_updated < ? "
+        data.append(end_time)
+
+    if entity_id is not None:
+        where += "AND entity_id = ? "
+        data.append(entity_id.lower())
+
+    query = ("SELECT * FROM states WHERE {} "
+             "ORDER BY entity_id, last_updated ASC").format(where)
+
+    states = recorder.query_states(query, data)
+
+    return states_to_json(states, start_time, entity_id)
+
+
 def state_changes_during_period(start_time, end_time=None, entity_id=None):
     """
     Return states changes during UTC period start_time - end_time.
@@ -55,20 +88,7 @@ def state_changes_during_period(start_time, end_time=None, entity_id=None):
 
     states = recorder.query_states(query, data)
 
-    result = defaultdict(list)
-
-    entity_ids = [entity_id] if entity_id is not None else None
-
-    # Get the states at the start time
-    for state in get_states(start_time, entity_ids):
-        state.last_changed = start_time
-        result[state.entity_id].append(state)
-
-    # Append all changes to it
-    for entity_id, group in groupby(states, lambda state: state.entity_id):
-        result[entity_id].extend(group)
-
-    return result
+    return states_to_json(states, start_time, entity_id)
 
 
 def get_states(utc_point_in_time, entity_ids=None, run=None):
@@ -100,6 +120,33 @@ def get_states(utc_point_in_time, entity_ids=None, run=None):
     return recorder.query_states(query, where_data)
 
 
+def states_to_json(states, start_time, entity_id):
+    """Converts SQL results into JSON friendly data structure.
+
+    This takes our state list and turns it into a JSON friendly data
+    structure {'entity_id': [list of states], 'entity_id2': [list of states]}
+
+    We also need to go back and create a synthetic zero data point for
+    each list of states, otherwise our graphs won't start on the Y
+    axis correctly.
+    """
+
+    result = defaultdict(list)
+
+    entity_ids = [entity_id] if entity_id is not None else None
+
+    # Get the states at the start time
+    for state in get_states(start_time, entity_ids):
+        state.last_changed = start_time
+        state.last_updated = start_time
+        result[state.entity_id].append(state)
+
+    # Append all changes to it
+    for entity_id, group in groupby(states, lambda state: state.entity_id):
+        result[entity_id].extend(group)
+    return result
+
+
 def get_state(utc_point_in_time, entity_id, run=None):
     """ Return a state at a specific point in time. """
     states = get_states(utc_point_in_time, (entity_id,), run)
@@ -152,4 +199,4 @@ def _api_history_period(handler, path_match, data):
     entity_id = data.get('filter_entity_id')
 
     handler.write_json(
-        state_changes_during_period(start_time, end_time, entity_id).values())
+        get_significant_states(start_time, end_time, entity_id).values())

tests/components/test_history.py

@@ -8,7 +8,7 @@ Tests the history component.
 from datetime import timedelta
 import os
 import unittest
-from unittest.mock import patch
+from unittest.mock import patch, sentinel
 
 import homeassistant.core as ha
 import homeassistant.util.dt as dt_util
@@ -143,3 +143,60 @@ class TestComponentHistory(unittest.TestCase):
         hist = history.state_changes_during_period(start, end, entity_id)
 
         self.assertEqual(states, hist[entity_id])
+
+    def test_get_significant_states(self):
+        """test that only significant states are returned with
+        get_significant_states.
+
+        We inject a bunch of state updates from media player and
+        thermostat. We should get back every thermostat change that
+        includes an attribute change, but only the state updates for
+        media player (attribute changes are not significant and not returned).
+
+        """
+        self.init_recorder()
+        mp = 'media_player.test'
+        therm = 'thermostat.test'
+
+        def set_state(entity_id, state, **kwargs):
+            self.hass.states.set(entity_id, state, **kwargs)
+            self.wait_recording_done()
+            return self.hass.states.get(entity_id)
+
+        zero = dt_util.utcnow()
+        one = zero + timedelta(seconds=1)
+        two = one + timedelta(seconds=1)
+        three = two + timedelta(seconds=1)
+        four = three + timedelta(seconds=1)
+
+        states = {therm: [], mp: []}
+        with patch('homeassistant.components.recorder.dt_util.utcnow',
+                   return_value=one):
+            states[mp].append(
+                set_state(mp, 'idle',
+                          attributes={'media_title': str(sentinel.mt1)}))
+            states[mp].append(
+                set_state(mp, 'YouTube',
+                          attributes={'media_title': str(sentinel.mt2)}))
+            states[therm].append(
+                set_state(therm, 20, attributes={'current_temperature': 19.5}))
+
+        with patch('homeassistant.components.recorder.dt_util.utcnow',
+                   return_value=two):
+            # this state will be skipped only different in time
+            set_state(mp, 'YouTube',
+                      attributes={'media_title': str(sentinel.mt3)})
+            states[therm].append(
+                set_state(therm, 21, attributes={'current_temperature': 19.8}))
+
+        with patch('homeassistant.components.recorder.dt_util.utcnow',
+                   return_value=three):
+            states[mp].append(
+                set_state(mp, 'Netflix',
+                          attributes={'media_title': str(sentinel.mt4)}))
+            # attributes changed even though state is the same
+            states[therm].append(
+                set_state(therm, 21, attributes={'current_temperature': 20}))
+
+        hist = history.get_significant_states(zero, four)
+        self.assertEqual(states, hist)