Monitor the temperature, humidity and pressure using the SenseHat sensors.

    You can either specify a threshold for each value and only emit a beacon
    if it is exceeded or define a range and emit a beacon when the value is
    out of range.

    Units:
    * humidity:                     percent
    * temperature:                  degrees Celsius
    * temperature_from_pressure:    degrees Celsius
    * pressure:                     Millibars

    .. code-block:: yaml

        beacons:
          sensehat:
            - sensors:
                humidity: 70%
                temperature: [20, 40]
                temperature_from_pressure: 40
                pressure: 1500

def beacon(config):
    '''
    Monitor the temperature, humidity and pressure using the SenseHat sensors.

    You can either specify a threshold for each value and only emit a beacon
    if it is exceeded or define a range and emit a beacon when the value is
    out of range.

    Units:
    * humidity:                     percent
    * temperature:                  degrees Celsius
    * temperature_from_pressure:    degrees Celsius
    * pressure:                     Millibars

    .. code-block:: yaml

        beacons:
          sensehat:
            - sensors:
                humidity: 70%
                temperature: [20, 40]
                temperature_from_pressure: 40
                pressure: 1500
    '''
    ret = []
    min_default = {
        'humidity': '0',
        'pressure': '0',
        'temperature': '-273.15'
    }

    _config = {}
    list(map(_config.update, config))

    for sensor in _config.get('sensors', {}):
        sensor_function = 'sensehat.get_{0}'.format(sensor)
        if sensor_function not in __salt__:
            log.error('No sensor for meassuring %s. Skipping.', sensor)
            continue

        sensor_config = _config['sensors'][sensor]
        if isinstance(sensor_config, list):
            sensor_min = six.text_type(sensor_config[0])
            sensor_max = six.text_type(sensor_config[1])
        else:
            sensor_min = min_default.get(sensor, '0')
            sensor_max = six.text_type(sensor_config)

        if '%' in sensor_min:
            sensor_min = re.sub('%', '', sensor_min)
        if '%' in sensor_max:
            sensor_max = re.sub('%', '', sensor_max)
        sensor_min = float(sensor_min)
        sensor_max = float(sensor_max)

        current_value = __salt__[sensor_function]()
        if not sensor_min <= current_value <= sensor_max:
            ret.append({
                'tag': 'sensehat/{0}'.format(sensor),
                sensor: current_value
            })

    return ret