Motion detection with ultrasonic sensor

import RPi.GPIO as GPIO
from gpiozero import Button, MotionSensor
from picamera import PiCamera
from time import sleep
from signal import pause
import time
import smtplib 
from email.mime.multipart import MIMEMultipart 
from email.mime.text import MIMEText 
from email.mime.base import MIMEBase 
from email import encoders
import glob,os
from email.mime.image import MIMEImage
from email.mime.multipart import MIMEMultipart
import RPi.GPIO as GPIO
import time





 

GPIO.setmode(GPIO.BCM)
 
GPIO_TRIGGER = 23
GPIO_ECHO = 24
 
GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)
 
def distance():
    GPIO.output(GPIO_TRIGGER, True)
 
    # set Trigger after 0.01ms to LOW
    time.sleep(0.00001)
    GPIO.output(GPIO_TRIGGER, False)
 
    StartTime = time.time()
    StopTime = time.time()
 
    while GPIO.input(GPIO_ECHO) == 0:
        StartTime = time.time()
 
    # save time of arrival
    while GPIO.input(GPIO_ECHO) == 1:
        StopTime = time.time()
 
    # time difference between start and arrival
    TimeElapsed = StopTime - StartTime
    # multiply with the sonic speed (34300 cm/s)
    # and divide by 2, because there and back
    distance = (TimeElapsed * 34300) / 2
 
    return distance
    time.sleep(8)
def a():
    GPIO.output(GPIO_TRIGGER, True)
 
    # set Trigger after 0.01ms to LOW
    time.sleep(0.0001)
    GPIO.output(GPIO_TRIGGER, False)
 
    StartTime = time.time()
    StopTime = time.time()
 
    while GPIO.input(GPIO_ECHO) == 0:
        StartTime = time.time()
 
    # save time of arrival
    while GPIO.input(GPIO_ECHO) == 1:
        StopTime = time.time()
 
    # time difference between start and arrival
    TimeElapsed = StopTime - StartTime
    # multiply with the sonic speed (34300 cm/s)
    # and divide by 2, because there and back
    a = (TimeElapsed * 34300) / 2
    return a
 
if __name__ == '__main__':
    try:
        while True:
            dist = distance()
            print ("Measured Distance = %.1f cm" % dist)
            a1=a()
            print ("a Distance = %.lf cm" % a1)
            a2=dist
            while True:
                    
                    print ("Measured Distance = %.1f cm" % a2)
                    a1=a()
                    print ("a Distance = %.lf cm" % a1)
                    
                    if (dist - a1 < 2) :
                        
                        print("")
                        a2=a1
                        
                    else:  
                        #create objects that refer to a button,
                        #a motion sensor and the PiCamera
                        button = Button(2)
                        pir = MotionSensor(4)
                        camera = PiCamera()

                        #start the camera
                        camera.rotation = 180
                        camera.start_preview()

                        #image image names
                        i = 0

                    #stop the camera when the pushbutton is pressed
                        def stop_camera():
                            camera.stop_preview()
                        #exit the program
                            exit()

        #take photo when motion is detected
                        def take_photo():
                            global i
                        i = i + 1
                        camera.capture('/home/pi/Desktop/image_%s.jpg' % i)
                        print('A photo has been taken')
                        sleep(1)

        #assign a function that runs when the button is pressed
                        button.when_pressed = stop_camera
        #assign a function that runs when motion is detected
                        pir.when_motion = take_photo
                        
                       # pause()
                        
                        
                        
                        TO = '500076405@stu.upes.ac.in'
                        SUBJECT = 'motion detected'
                        TEXT = 'There is a motion detected \n picture taken.'
                        
                        # Gmail Sign In
                        gmail_sender = 'example@gmail.com'              #the email of your email
                        gmail_passwd = '**********'                     #the Password of your email
                        
                        
                        server = smtplib.SMTP('smtp.gmail.com', 587)
                        server.ehlo()
                        server.starttls()
                        server.login(gmail_sender, gmail_passwd)
                        
                        
                        BODY = '\r\n'.join(['To: %s' % TO,
                                            'From: %s' % gmail_sender,
                                            'Subject: %s' % SUBJECT,
                                            '', TEXT])
                        
                        
                        try:
                            server.sendmail(gmail_sender, [TO], BODY)
                            print ('email sent')
                        except:
                            print ('error sending mail')
                            
                            
                            
                        
                        
                       

                        
                        
                        GPIO.setup(6, GPIO.OUT) # output rf
                        GPIO.setmode(GPIO.BCM)
 
                        GPIO_TRIGGER = 23
                        GPIO_ECHO = 24
                         
                        GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
                        GPIO.setup(GPIO_ECHO, GPIO.IN)
                          
                        
                        #server.quit()
                        
                    time.sleep(1)
                    
                    
                    
                    
 
        # Reset by pressing CTRL + C
    except KeyboardInterrupt:
        print("Measurement stopped by User")
        GPIO.cleanup()



   
 
  
# terminating the session 
s.quit()