#!/usr/bin/env python
#This code counts how many times the reed switch of the anemometer closes the circuit
#in every rotation it happens two times. We then can translate the number of counts
#in distance knowing the radius of the anemometer and using the equation of 2*pi*radius
#We then calculate speed of the wind, dividing the distance by time, fixing a given
#predermined period of time (wind_interval). Just make sure you leave the same number in
#wind_interval and in the client.loop (timestamp + number).
import cayenne.client
from gpiozero import Button
import time
import logging
import math

MQTT_USERNAME  = "xxxx"
MQTT_PASSWORD  = "xxxx"
MQTT_CLIENT_ID = "xxxx"

wind_count = 0 # counts how many half-rotations

radius_cm = 9.0 # radius in cm of the anemometer

wind_interval = 5 # how often (secs) to report speed

ADJUSTMENT = 1.18 # adjustment of the anemometer given by the manufacturer

# The callback for when a message is received from Cayenne.
def on_message(message):
    print("message received: " + str(message))
    # If there is an error processing the message return an error string, otherwise return nothing.

client = cayenne.client.CayenneMQTTClient()
client.on_message = on_message
client.begin(MQTT_USERNAME, MQTT_PASSWORD, MQTT_CLIENT_ID,port=8883)

# every half-rotation, add 1 count

def spin():
 
    global wind_count

    wind_count = wind_count + 1

    # print("spin" + str(wind_count))


# calculate the wind speed

def calculate_speed(time_sec):

        global wind_count

        circumference_cm = (2 * math.pi) * radius_cm

        rotations = wind_count / 2.0

        dist_km = (circumference_cm * rotations) / 100000.0 # divided by cm in a km

        km_per_sec = dist_km / time_sec

        km_per_hour = km_per_sec * 3600 # multiplied by secs in an hour

        return km_per_hour * ADJUSTMENT



def reset_wind():

    global wind_count

    wind_count = 0

    # recommended function to reset the wind_count to zero when assembling the weather station


wind_speed_sensor = Button(5)

wind_speed_sensor.when_pressed = spin


i=0
timestamp = 0

# loop to measure wind speed and report at 5 secs interval. Number after

while True:
        client.loop()
        if (time.time() > timestamp + 5):
                x = calculate_speed(wind_interval)
                client.virtualWrite(1,x)
                print(x)
                wind_count = 0
                timestamp = time.time()