import os
import time
import RPi.GPIO as GPIO
import logging

logging.basicConfig(filename='fanControl.log', filemode='w', level=logging.DEBUG)
logging.info("fanControl Log. Started: " + time.strftime("%d/%m/%Y") + " " + time.strftime("%H:%M:%S"))

print "Fan Control Started"

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
#Set max. temperature of CPU
TEMP_MAX = 65
#Set ON-Time for the fan when the max. temperature has reached
ON_TIME = 4
#Set pin 4 as transistor gate
GATE = 4
#Set pin 4 as an output and shut down
GPIO.setup(GATE, GPIO.OUT)
GPIO.output(GATE, False)

logging.info("GPIO Output: " + str(GATE))
logging.info("Fan On Time: " + str(ON_TIME))
logging.info("Fan on Temp: " + str(TEMP_MAX))
logging.info("================================")

#pulse at start to show operative
InitFlash = 0

while InitFlash < 3 :
    GPIO.output(GATE, True)
    time.sleep(4)
    GPIO.output(GATE, False)
    time.sleep(4)
    InitFlash += 1

def getCPUtemperature():
    res = os.popen('vcgencmd measure_temp').readline()
    return(res.replace("temp=","").replace("'C\n",""))

while True:

    temp_float = float(getCPUtemperature())

    try:
        if (temp_float > TEMP_MAX):
            logging.info("-------------------------------------")
            logging.info(time.strftime("%M:%S: ") + "Fan on at: " + str(temp_float))
            on_temp = temp_float
            # ein
            GPIO.output(GATE, True)
            time.sleep(ON_TIME)
            # aus
            temp_float = float(getCPUtemperature())
            logging.info(time.strftime("%M:%S: ") + "Temp at end of Fan period: " + str(temp_float))
            logging.info(time.strftime("%M:%S: ") + "Temp difference: " + str(on_temp-temp_float))
            if on_temp - temp_float < 0.5:
                ON_TIME = ON_TIME + 2
                logging.info(time.strftime("%M:%S: ") + "Cooling small. Increased Fan on time to: " + str(ON_TIME))
            GPIO.output(GATE, False)
        else:
            GPIO.output(GATE, False)

    except KeyboardInterrupt:
        print float(getCPUtemperature())
        print "power off fan..."
        GPIO.output(GATE, False)
        print "cancelling..."

    time.sleep(2)