import RPi.GPIO as GPIO
import time
import subprocess
from threading import Timer

SHUTDOWN_HOLD_TIME = 5 # Time in seconds that power button must be held
SHUTDOWN_PIN = 5 # Pin to trigger shutdown, pin 5 will also start up the pi when it's off

# GPIO.BOARD means use pin numbering to matching the pins on the Pi, instead of the
# CPU's actual pin numbering (makes it easier to keep track of things)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(SHUTDOWN_PIN, GPIO.IN, pull_up_down = GPIO.PUD_UP)

buttonReleased = True
while buttonReleased:
    GPIO.wait_for_edge(SHUTDOWN_PIN, GPIO.FALLING)
    # button has been pressed
    buttonReleased = False
    for i in range(SHUTDOWN_HOLD_TIME * 10):
        time.sleep(0.1)
        if GPIO.input(SHUTDOWN_PIN):
            buttonReleased = True
            break

GPIO.cleanup()
subprocess.call("shutdown -h now", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)