Add support for monitoring nzbget

Calculate average download rate the same way as downloadrate



Add config option for choosing which nzbget variables to monitor, and provide a default



Pep8 fixes



Refactoring and changes based on @balloob's comments



Add nzbget.py to .coveragerc omit list.  Check if there are any http

errors (like bad auth) when creating the nzbgetapi class.   If there

are, the setup_platform() function will return false.  Exceptions are

logged as well.

When a new sensor is created, assign the initial value from the api

instead of simply using None until the first update call.

.coveragerc

@@ -139,6 +139,7 @@ omit =
     homeassistant/components/sensor/glances.py
     homeassistant/components/sensor/gtfs.py
     homeassistant/components/sensor/netatmo.py
+    homeassistant/components/sensor/nzbget.py
     homeassistant/components/sensor/loopenergy.py
     homeassistant/components/sensor/neurio_energy.py
     homeassistant/components/sensor/onewire.py

homeassistant/components/sensor/nzbget.py

@@ -0,0 +1,164 @@
+"""
+Support for monitoring NZBGet nzb client.
+
+Uses NZBGet's JSON-RPC API to query for monitored variables.
+"""
+import logging
+from datetime import timedelta
+import requests
+
+from homeassistant.helpers.entity import Entity
+from homeassistant.util import Throttle
+
+REQUIREMENTS = []
+SENSOR_TYPES = {
+    "ArticleCacheMB": ("Article Cache", "MB"),
+    "AverageDownloadRate": ("Average Speed", "MB/s"),
+    "DownloadRate": ("Speed", "MB/s"),
+    "DownloadPaused": ("Download Paused", None),
+    "FreeDiskSpaceMB": ("Disk Free", "MB"),
+    "PostPaused": ("Post Processing Paused", None),
+    "RemainingSizeMB": ("Queue Size", "MB"),
+}
+DEFAULT_TYPES = [
+    "DownloadRate",
+    "DownloadPaused",
+    "RemainingSizeMB",
+]
+
+_LOGGER = logging.getLogger(__name__)
+
+
+# pylint: disable=unused-argument
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Set up nzbget sensors."""
+    base_url = config.get("base_url")
+    name = config.get("name", "NZBGet")
+    username = config.get("username")
+    password = config.get("password")
+    monitored_types = config.get("monitored_variables", DEFAULT_TYPES)
+
+    if not base_url:
+        _LOGGER.error("Missing base_url config for NzbGet")
+        return False
+
+    url = "{}/jsonrpc".format(base_url)
+
+    try:
+        nzbgetapi = NZBGetAPI(api_url=url,
+                              username=username,
+                              password=password)
+        nzbgetapi.update()
+    except (requests.exceptions.ConnectionError,
+            requests.exceptions.HTTPError) as conn_err:
+        _LOGGER.error("Error setting up NZBGet API: %r", conn_err)
+        return False
+
+    devices = []
+    for ng_type in monitored_types:
+        if ng_type in SENSOR_TYPES:
+            new_sensor = NZBGetSensor(api=nzbgetapi,
+                                      sensor_type=ng_type,
+                                      client_name=name)
+            devices.append(new_sensor)
+        else:
+            _LOGGER.error("Unknown nzbget sensor type: %s", ng_type)
+    add_devices(devices)
+
+
+class NZBGetAPI(object):
+    """Simple json-rpc wrapper for nzbget's api."""
+
+    def __init__(self, api_url, username=None, password=None):
+        """Initialize NZBGet API and set headers needed later."""
+        self.api_url = api_url
+        self.status = None
+        self.headers = {'content-type': 'application/json'}
+        if username is not None and password is not None:
+            self.auth = (username, password)
+        else:
+            self.auth = None
+        # set the intial state
+        self.update()
+
+    def post(self, method, params=None):
+        """Send a post request, and return the response as a dict."""
+        payload = {"method": method}
+        if params:
+            payload['params'] = params
+        try:
+            response = requests.post(self.api_url,
+                                     json=payload,
+                                     auth=self.auth,
+                                     headers=self.headers,
+                                     timeout=30)
+            response.raise_for_status()
+            return response.json()
+        except requests.exceptions.ConnectionError as conn_exc:
+            _LOGGER.error("Failed to update nzbget status from %s.  Error: %s",
+                          self.api_url, conn_exc)
+            raise
+
+    @Throttle(timedelta(seconds=5))
+    def update(self):
+        """Update cached response."""
+        try:
+            self.status = self.post('status')['result']
+        except requests.exceptions.ConnectionError:
+            # failed to update status - exception already logged in self.post
+            raise
+
+
+class NZBGetSensor(Entity):
+    """Represents an NZBGet sensor."""
+
+    def __init__(self, api, sensor_type, client_name):
+        """Initialize a new NZBGet sensor."""
+        self._name = client_name + ' ' + SENSOR_TYPES[sensor_type][0]
+        self.type = sensor_type
+        self.client_name = client_name
+        self.api = api
+        self._state = None
+        self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
+        # Set initial state
+        self.update()
+        _LOGGER.debug("created nzbget sensor %r", self)
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def state(self):
+        """Return the state of the sensor."""
+        return self._state
+
+    @property
+    def unit_of_measurement(self):
+        """Unit of measurement of this entity, if any."""
+        return self._unit_of_measurement
+
+    def update(self):
+        """Update state of sensor."""
+        try:
+            self.api.update()
+        except requests.exceptions.ConnectionError:
+            # Error calling the api, already logged in api.update()
+            return
+
+        if self.api.status is None:
+            _LOGGER.debug("update of %s requested, but no status is available",
+                          self._name)
+            return
+
+        value = self.api.status.get(self.type)
+        if value is None:
+            _LOGGER.warning("unable to locate value for %s", self.type)
+            return
+
+        if "DownloadRate" in self.type and value > 0:
+            # Convert download rate from bytes/s to mb/s
+            self._state = value / 1024 / 1024
+        else:
+            self._state = value