#!/usr/bin/env python
# -*- coding: utf-8 -*-

import time, os, sys, signal, setproctitle, traceback

MIN_TEMP = 50 # fan starts to cool
MAX_TEMP = 80 # fan cooling full power

def call_acpi(command):
    acpi_call = open('/proc/acpi/call', 'w')
    acpi_call.write(command)
    acpi_call.close()
    
    # Response
    acpi_call = open('/proc/acpi/call')
    response = acpi_call.read()
    acpi_call.close()
    
    return response

def set_fan(speed, fan=1):
    if speed < 0:
        speed = 0
    elif speed > 100:
        speed = 100
    raw_speed = round(speed * 2.55)
    call_acpi('\_SB.PCI0.LPCB.EC0.SFNV %d %s' % (fan, raw_speed))
    
    print('Set fan speed to %d %%' % speed)
    
def get_cpu_temp():
    return int(call_acpi('\_SB.PCI0.LPCB.EC0.ECPU')[:4], 16)

# you can adjust the fan behavior with any mathematic function
# for example you can use a square function "return temp**2* or cubic "return temp**3"
def scale_temp(temp):
    return temp

def handle_fan(current_temp):
    temp_range = MAX_TEMP - MIN_TEMP
    norm_temp = current_temp - MIN_TEMP if (current_temp - MIN_TEMP) > 0 else 0
            
    scaled_temp = scale_temp(norm_temp)
    scaled_border = scale_temp(temp_range)
    
    fan_speed = 100/scaled_border * scaled_temp # in percent
        
    print("Current CPU temperature %d°" % current_temp)
    
    set_fan(fan_speed, 1)
    set_fan(fan_speed, 2)
    
def cleanup(signal=None, frame=None):
    call_acpi('\_SB.PCI0.LPCB.EC0.SFNV 0 0')
    call_acpi('\_SB.ATKD.QMOD 0x02')
    
    print('\nReset fan control to automatic. Exiting...')
    sys.exit(0)

def main():
    signal.signal(signal.SIGTERM, cleanup)
    try:
        while True:
            handle_fan(get_cpu_temp())
            time.sleep(2)
    except:
        traceback.print_exc()
    finally:
        cleanup()

if __name__=='__main__':
    # TODO: only one instance
    setproctitle.setproctitle('fancontrol')
    main(