#!/usr/bin/env python3
import cayenne.client
import time
import logging
import board
import busio
import digitalio
import adafruit_bme280
import math
import scipy

# Cayenne authentication info. This should be obtained from the Cayenne Dashboard.
MQTT_USERNAME  = "19cfb8a0-82e7-11e8-9464-a9a522c157c5"
MQTT_PASSWORD  = "cc4752158e665ff01ab325271ff06017c200a457"
MQTT_CLIENT_ID = "489fe300-d6ea-11e9-a38a-d57172a4b4d4"

client = cayenne.client.CayenneMQTTClient()
client.begin(MQTT_USERNAME, MQTT_PASSWORD, MQTT_CLIENT_ID)
# For a secure connection use port 8883 when calling client.begin:
# client.begin(MQTT_USERNAME, MQTT_PASSWORD, MQTT_CLIENT_ID, port=8883, loglevel=logging.INFO)

#Defining VPD calculation function
def ea_calc(airtemp= scipy.array([]),\
            rh= scipy.array([])):
    '''
    Function to calculate actual vapour pressure from relative humidity:

    .. math::
        e_a = \\frac{rh \\cdot e_s}{100}

    where es is the saturated vapour pressure at temperature T.
    Parameters:
        - airtemp: array of measured air temperatures [Celsius].
        - rh: Relative humidity [%].
    Returns:
        - ea: array of actual vapour pressure [Pa].
    Examples
    --------

        >>> ea_calc(25,60)
        1900.0946514729308
    '''

    # Test input array/value
    airtemp,rh = _arraytest(airtemp, rh)

    # Calculate saturation vapour pressures
    es = es_calc(airtemp)
    # Calculate actual vapour pressure
    eact = rh / 100.0 * es
    return eact # in Pa

def es_calc(airtemp= scipy.array([])):
    '''
    Function to calculate saturated vapour pressure from temperature.
    For T<0 C the saturation vapour pressure equation for ice is used
    accoring to Goff and Gratch (1946), whereas for T>=0 C that of
    Goff (1957) is used.

    Parameters:
        - airtemp : (data-type) measured air temperature [Celsius].

    Returns:
        - es : (data-type) saturated vapour pressure [Pa].
    References
    ----------

    - Goff, J.A.,and S. Gratch, Low-pressure properties of water from -160 \
    to 212 F. Transactions of the American society of heating and \
    ventilating engineers, p. 95-122, presented at the 52nd annual \
    meeting of the American society of \
    heating and ventilating engineers, New York, 1946.
    - Goff, J. A. Saturation pressure of water on the new Kelvin \
    temperature scale, Transactions of the American \
    society of heating and ventilating engineers, pp 347-354, \
    presented at the semi-annual meeting of the American \
    society of heating and ventilating engineers, Murray Bay, \
    Quebec. Canada, 1957.
    Examples
    --------
        >>> es_calc(30.0)
        4242.725994656632
        >>> x = [20, 25]
        >>> es_calc(x)
        array([ 2337.08019792,  3166.82441912])

    '''

    # Test input array/value
    airtemp = _arraytest(airtemp)

    # Determine length of array
    n = scipy.size(airtemp)
    # Check if we have a single (array) value or an array
    if n < 2:
        # Calculate saturated vapour pressures, distinguish between water/ice
        if airtemp < 0:
            # Calculate saturation vapour pressure for ice
            log_pi = - 9.09718 * (273.16 / (airtemp + 273.15) - 1.0) \
                     - 3.56654 * math.log10(273.16 / (airtemp + 273.15)) \
                     + 0.876793 * (1.0 - (airtemp + 273.15) / 273.16) \
                     + math.log10(6.1071)
            es = math.pow(10, log_pi)
        else:
            # Calculate saturation vapour pressure for water
            log_pw = 10.79574 * (1.0 - 273.16 / (airtemp + 273.15)) \
                     - 5.02800 * math.log10((airtemp + 273.15) / 273.16) \
                     + 1.50475E-4 * (1 - math.pow(10, (-8.2969 * ((airtemp +\
                     273.15) / 273.16 - 1.0)))) + 0.42873E-3 * \
                     (math.pow(10, (+4.76955 * (1.0 - 273.16\
                     / (airtemp + 273.15)))) - 1) + 0.78614
            es = math.pow(10, log_pw)
    else:   # Dealing with an array
        # Initiate the output array
        es = scipy.zeros(n)
        # Calculate saturated vapour pressures, distinguish between water/ice
        for i in range(0, n):
            if airtemp[i] < 0:
                # Saturation vapour pressure equation for ice
                log_pi = - 9.09718 * (273.16 / (airtemp[i] + 273.15) - 1.0) \
                         - 3.56654 * math.log10(273.16 / (airtemp[i] + 273.15)) \
                         + 0.876793 * (1.0 - (airtemp[i] + 273.15) / 273.16) \
                         + math.log10(6.1071)
                es[i] = math.pow(10, log_pi)
            else:
                # Calculate saturation vapour pressure for water
                log_pw = 10.79574 * (1.0 - 273.16 / (airtemp[i] + 273.15)) \
                         - 5.02800 * math.log10((airtemp[i] + 273.15) / 273.16) \
                         + 1.50475E-4 * (1 - math.pow(10, (-8.2969\
                         * ((airtemp[i] + 273.15) / 273.16 - 1.0)))) + 0.42873E-3\
                         * (math.pow(10, (+4.76955 * (1.0 - 273.16\
                         / (airtemp[i] + 273.15)))) - 1) + 0.78614
                es[i] = pow(10, log_pw)
    # Convert from hPa to Pa
    es = es * 100.0
    return es # in Pa


def _arraytest(*args):
    '''
    Function to convert input parameters in as lists or tuples to
    arrays, while leaving single values intact.
    Test function for single values or valid array parameter input
    (J. Delsman).
    Parameters:
        args (array, list, tuple, int, float): Input values for functions.
    Returns:
        rargs (array, int, float): Valid single value or array function input.
    Examples
    --------

        >>> _arraytest(12.76)
        12.76
        >>> _arraytest([(1,2,3,4,5),(6,7,8,9)])
        array([(1, 2, 3, 4, 5), (6, 7, 8, 9)], dtype=object)
        >>> x=[1.2,3.6,0.8,1.7]
        >>> _arraytest(x)
        array([ 1.2,  3.6,  0.8,  1.7])
        >>> _arraytest('This is a string')
        'This is a string'
    '''

    rargs=[]
    for a in args:
        if isinstance(a, (list, tuple)):
            rargs.append(scipy.array(a))
        else:
            rargs.append(a)
    if len(rargs) == 1:
        return rargs[0] # no unpacking if single value, return value i/o list
    else:
        return rargs

def vpd_calc(airtemp= scipy.array([]),\
             rh= scipy.array([])):
    '''
    Function to calculate vapour pressure deficit.
    Parameters:
        - airtemp: measured air temperatures [Celsius].
        - rh: (array of) rRelative humidity [%].

    Returns:
        - vpd: (array of) vapour pressure deficits [Pa].

    Examples
    --------

        >>> vpd_calc(30,60)
        1697.090397862653
        >>> T=[20,25]
        >>> RH=[50,100]
        >>> vpd_calc(T,RH)
        array([ 1168.54009896,     0.        ])

    '''

    # Test input array/value
    airtemp,rh = _arraytest(airtemp, rh)

    # Calculate saturation vapour pressures
    es = es_calc(airtemp)
    eact = ea_calc(airtemp, rh)
    # Calculate vapour pressure deficit
    vpd = es - eact
    return vpd # in hPa



#initiate SPI bus
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
cs = digitalio.DigitalInOut(board.D5)
bme280 = adafruit_bme280.Adafruit_BME280_SPI(spi, cs)

i=0
timestamp = 0

#calculating vpd
#vpd = vpd_calc(bme280.temperature, bme280.humidity)/100

while True:
    client.loop()

    if (time.time() > timestamp + 10):
        client.celsiusWrite(1, bme280.temperature)
        client.virtualWrite(2, bme280.humidity, "rel_hum", "p")
        client.hectoPascalWrite(4, (vpd_calc(bme280.temperature, bme280.humidity)/100))
        client.hectoPascalWrite(3, bme280.pressure)
        timestamp = time.time()
        i = i+1