#!/usr/bin/python
#
#   $ Air Sensors
#   $ Beta 1: Revision 001a $
#   $ Author: WhimickRH $
#   $ US - UK $
#   $ Date: 2017-10-29 $
#   $ Wind_Rain $
#   $ For GrovePi Weather Station $
#   $ Raspberry Pi Air Sensors $
#   $

import sys
import time
import threading
from multiprocessing import Process
import logging
import smbus
import RPi.GPIO as GPIO
import grovepi
import atexit
import cPickle

# -------------------------------GROVEPI BOARD & SENSOR SET UP-------------------------------

rev = GPIO.RPI_REVISION
if rev == 2 or rev == 3:
	bus = smbus.SMBus(1)
else:
	bus = smbus.SMBus(0)

GPIO.setwarnings(False)

atexit.register(grovepi.dust_sensor_dis)
grovepi.dust_sensor_en()

# -------------------------------ERROR LOGGING-----------------------------------------------

logging.basicConfig(filename='/home/pi/WxRam/Air_Sensors_Error.txt', filemode='a', level=logging.ERROR,
	format='%(asctime)s %(levelname)s %(name)s %(message)s')
logger=logging.getLogger(__name__)

# -------------------------------AIR SENSORS CLASS-------------------------------------

class Air_Sensors(object):
	
	def __init__(self):
		self.dust_ppm = 0
		self.starttime = time.time()
		
# -------------------------------READ DUST SENSOR & DUST SENSOR LOOP----------------------------
	
	def dust_sensor(self):
		
		reading_no = 0
		print("Starting Dust Sensor")
		while True:
			try:
				[new_val,lowpulseoccupancy] = grovepi.dustSensorRead()
				if new_val:
					self.lowpulseoccupancy = lowpulseoccupancy
					reading_no +=1
					air_file = open("/home/pi/WxRam/air.txt", 'w')
					print("Reading_no:",reading_no, "Dust lowpulseoccupancy",self.lowpulseoccupancy)
					cPickle.dump(self.lowpulseoccupancy, air_file)
					air_file.close()
				time.sleep(5.0 - ((time.time() - self.starttime) % 5.0))
			except Exception as e:
				logging.exception(str(e))
				print(logging.exception(str(e)))
		
# -------------------------------MAIN --------------------------------------------------------

def main():
	
	Gas = Air_Sensors()
	Air_loop = threading.Thread(name='dust_sensor', target=Gas.dust_sensor())
	# Air_loop = Process(target=Gas.dust_sensor(), args=())
	Air_loop.setDaemon(True)
	Air_loop.start()
	return

# --------------------------------RUN MAIN----------------------------------------------------

if __name__ == '__main__':
	try:
		main()
	except Exception as e:
		logging.exception(str(e))
		print(logging.exception(str(e)))
		sys.exit()

"""

lowpulseoccupancy is the number of ms in a 30 second period for which the sensor data was low which indicates a reading
from the dust sensor. If you check the wiki here: http://www.seeedstudio.com/wiki/Grove_-_Dust_Sensor18,
to change that into concentration just do this:
ratio = lowpulseoccupancy/(sampletime_ms*10.0) # Integer percentage
concentration = 1.1*pow(ratio,3)-3.8*pow(ratio,2)+520*ratio+0.62 #using spec sheet curve

"""