import Adafruit_DHT
import RPi.GPIO as GPIO  # Import GPIO library
import time  # Import time library

GPIO.setmode(GPIO.BCM)

PIR = 21
TRIG = 23                                  #Associate pin 23 to TRIG
ECHO = 24
BUZZER = 18

SAFE_DOOR = 50

GPIO.setup(PIR, GPIO.IN) #PIR

GPIO.setup(BUZZER, GPIO.OUT)

GPIO.setup(TRIG,GPIO.OUT)                  #Set pin as GPIO out
GPIO.setup(ECHO,GPIO.IN)


def checkDistance():
    GPIO.output(TRIG, False)  # Set TRIG as LOW
    GPIO.output(TRIG, True)  # Set TRIG as HIGH
    time.sleep(0.00001)  # Delay of 0.00001 seconds
    GPIO.output(TRIG, False)  # Set TRIG as LOW

    while GPIO.input(ECHO) == 0:  # Check whether the ECHO is LOW
        pulse_start = time.time()  # Saves the last known time of LOW pulse

    while GPIO.input(ECHO) == 1:  # Check whether the ECHO is HIGH
        pulse_end = time.time()  # Saves the last known time of HIGH pulse

    pulse_duration = pulse_end - pulse_start  # Get pulse duration to a variable

    distance = pulse_duration * 17150  # Multiply pulse duration by 17150 to get distance
    distance = round(distance, 2)  # Round to two decimal points

    if distance > 2 and distance < 400:  # Check whether the distance is within range
        # print("Distance:",distance - 0.5,"cm")  #Print distance with 0.5 cm calibration
        return distance - 0.5
    else:
        # print("Out Of Range")                   #display out of range
        return -1

def check_PIR():
    if GPIO.input(PIR):
        time.sleep(5) #to avoid multiple detection
        return True
    return False


def start_buzzer():
    GPIO.output(BUZZER, True)


def stop_buzzer():
    GPIO.output(BUZZER, False)


def main():
    while True:
        if check_PIR():
            if checkDistance() < SAFE_DOOR:
                start_buzzer()
                time.sleep(20)
                stop_buzzer()