Improve usage module, consolidate API with emeter (#249)

* Consolidate API for both emeter&usage modules
* Add new cli command 'usage' to query usage

kasa/modules/usage.py

@@ -17,22 +17,53 @@ class Usage(Module):
             req, self.query_for_command("get_daystat", {"year": year, "month": month})
         )
         req = merge(req, self.query_for_command("get_monthstat", {"year": year}))
-        req = merge(req, self.query_for_command("get_next_action"))
 
         return req
 
-    async def get_daystat(self, year, month):
-        """Return stats for the current day."""
+    @property
+    def daily_data(self):
+        """Return statistics on daily basis."""
+        return self.data["get_daystat"]["day_list"]
+
+    @property
+    def monthly_data(self):
+        """Return statistics on monthly basis."""
+        return self.data["get_monthstat"]["month_list"]
+
+    @property
+    def usage_today(self):
+        """Return today's usage in minutes."""
+        today = datetime.now().day
+        converted = [x["time"] for x in self.daily_data if x["day"] == today]
+        if not converted:
+            return None
+
+        return converted.pop()
+
+    @property
+    def usage_this_month(self):
+        """Return usage in this month in minutes."""
+        this_month = datetime.now().month
+        converted = [x["time"] for x in self.monthly_data if x["month"] == this_month]
+        if not converted:
+            return None
+
+        return converted.pop()
+
+    async def get_daystat(self, *, year=None, month=None):
+        """Return daily stats for the given year & month."""
         if year is None:
             year = datetime.now().year
         if month is None:
             month = datetime.now().month
+
         return await self.call("get_daystat", {"year": year, "month": month})
 
-    async def get_monthstat(self, year):
-        """Return stats for the current month."""
+    async def get_monthstat(self, *, year=None):
+        """Return monthly stats for the given year."""
         if year is None:
             year = datetime.now().year
+
         return await self.call("get_monthstat", {"year": year})
 
     async def erase_stats(self):