from config import dht_gpio
try:
    import Adafruit_DHT as dht
except ImportError:
    dht = None

try:
    import Adafruit_BMP.BMP085 as bmp
except ImportError:
    bmp = None

#TODO: background process for value sensing (every x seconds)

KEY_TEMPERATURE = 't'
KEY_HUMIDITY = 'h'
KEY_PRESSURE = 'p'


class EnvSens(object):
    def __init__(self):
        if bmp is not None:
            self.bmp = bmp.BMP085()

    def get_env_data(self):
        #
        # DHT22
        #
        if dht is None:
            h = -17.3
            t = -125.7
        else:
            h, t = dht.read_retry(dht.DHT22, dht_gpio)
        #
        # BMP180
        #
        if bmp is None:
            p = -1024.17
        else:
            p = self.bmp.read_pressure()/100.
        return {KEY_TEMPERATURE: t, KEY_HUMIDITY: h, KEY_PRESSURE: p}