Add One-Time Password sensor (OTP) (#8332)

.coveragerc

@@ -453,6 +453,7 @@ omit =
     homeassistant/components/sensor/openexchangerates.py
     homeassistant/components/sensor/opensky.py
     homeassistant/components/sensor/openweathermap.py
+    homeassistant/components/sensor/otp.py
     homeassistant/components/sensor/pi_hole.py
     homeassistant/components/sensor/plex.py
     homeassistant/components/sensor/pocketcasts.py

homeassistant/components/sensor/otp.py

@@ -0,0 +1,90 @@
+"""
+Support for One-Time Password (OTP).
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.otp/
+"""
+import time
+import asyncio
+import logging
+
+import voluptuous as vol
+
+from homeassistant.core import callback
+import homeassistant.helpers.config_validation as cv
+from homeassistant.components.sensor import PLATFORM_SCHEMA
+from homeassistant.const import (CONF_NAME, CONF_TOKEN)
+from homeassistant.helpers.entity import Entity
+
+REQUIREMENTS = ['pyotp==2.2.6']
+
+_LOGGER = logging.getLogger(__name__)
+
+DEFAULT_NAME = 'OTP Sensor'
+
+TIME_STEP = 30  # Default time step assumed by Google Authenticator
+
+ICON = 'mdi:update'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_TOKEN): cv.string,
+    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
+})
+
+
+@asyncio.coroutine
+def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
+    """Set up the OTP sensor."""
+    name = config.get(CONF_NAME)
+    token = config.get(CONF_TOKEN)
+
+    async_add_devices([TOTPSensor(name, token)], True)
+    return True
+
+
+# Only TOTP supported at the moment, HOTP might be added later
+class TOTPSensor(Entity):
+    """Representation of a TOTP sensor."""
+
+    def __init__(self, name, token):
+        """Initialize the sensor."""
+        import pyotp
+        self._name = name
+        self._otp = pyotp.TOTP(token)
+        self._state = None
+        self._next_expiration = None
+
+    @asyncio.coroutine
+    def async_added_to_hass(self):
+        """Handle when an entity is about to be added to Home Assistant."""
+        self._call_loop()
+
+    @callback
+    def _call_loop(self):
+        self._state = self._otp.now()
+        self.hass.async_add_job(self.async_update_ha_state())
+
+        # Update must occur at even TIME_STEP, e.g. 12:00:00, 12:00:30,
+        # 12:01:00, etc. in order to have synced time (see RFC6238)
+        self._next_expiration = TIME_STEP - (time.time() % TIME_STEP)
+        self.hass.loop.call_later(self._next_expiration, self._call_loop)
+
+    @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 should_poll(self):
+        """No polling needed."""
+        return False
+
+    @property
+    def icon(self):
+        """Return the icon to use in the frontend."""
+        return ICON

requirements_all.txt

@@ -643,6 +643,9 @@ pynut2==2.1.2
 # homeassistant.components.binary_sensor.nx584
 pynx584==0.4
 
+# homeassistant.components.sensor.otp
+pyotp==2.2.6
+
 # homeassistant.components.sensor.openweathermap
 # homeassistant.components.weather.openweathermap
 pyowm==2.7.1