Refactor battery info update

- `self[BATTERY_STATUS] = BATTERY_STATUS[battery_status]` should be:
  `self[BATTERY_STATUS] = _hidpp20.BATTERY_STATUS[battery_status]`, otherwise
  the battery status would be a single char from the string `battery-status`.
- Make `_hidpp20.BATTERY_OK` check against strings instead of a number.
- Move setting battery information to a separate function, `set_battery_info`.
  This prepares for notifications when a battery error/warning occurs.

lib/logitech/unifying_receiver/hidpp20.py

@@ -59,7 +59,7 @@ FIRMWARE_KIND = _NamedInts(
 				Hardware=0x02,
 				Other=0x03)
 
-BATTERY_OK = lambda status: status < 5
+BATTERY_OK = lambda status: status not in ("invalid_battery", "thermal_error")
 
 BATTERY_STATUS = _NamedInts(
 				discharging=0x00,

lib/logitech/unifying_receiver/status.py

@@ -125,6 +125,24 @@ class DeviceStatus(dict):
 		return bool(self._active)
 	__nonzero__ = __bool__
 
+	def set_battery_info(self, level, status):
+		self[BATTERY_LEVEL] = level
+		self[BATTERY_STATUS] = status
+		error = None
+		if _hidpp20.BATTERY_OK(status):
+			alert = ALERT.NONE
+			reason = self[ERROR] = None
+			if _log.isEnabledFor(_DEBUG):
+				_log.debug("%s: battery %d%% charged, %s", self._device, level, status)
+		else:
+			alert = ALERT.ALL
+			error = status
+			_log.warn("%s: battery %d%% charged, ALERT %s", self._device, level, error)
+		if error is not None:
+			# TODO: show visual warning/notif to user
+			self[ERROR] = error
+		self._changed(alert=alert, reason=error)
+
 	def read_battery(self, timestamp=None):
 		d = self._device
 		if d and self._active:
@@ -294,18 +312,7 @@ class DeviceStatus(dict):
 			if n.address == 0x00:
 				discharge = ord(n.data[:1])
 				battery_status = ord(n.data[1:2])
-				self[BATTERY_LEVEL] = discharge
-				self[BATTERY_STATUS] = BATTERY_STATUS[battery_status]
-				if _hidpp20.BATTERY_OK(battery_status):
-					alert = ALERT.NONE
-					reason = self[ERROR] = None
-					if _log.isEnabledFor(_DEBUG):
-						_log.debug("%s: battery %d%% charged, %s", self._device, discharge, self[BATTERY_STATUS])
-				else:
-					alert = ALERT.ALL
-					reason = self[ERROR] = self[BATTERY_STATUS]
-					_log.warn("%s: battery %d%% charged, ALERT %s", self._device, discharge, reason)
-				self._changed(alert=alert, reason=reason)
+				self.set_battery_info(discharge, _hidpp20.BATTERY_STATUS[battery_status])
 			else:
 				_log.info("%s: unknown BATTERY %s", self._device, n)
 			return True