#include <Servo.h> //This line is needed to use the servo library
Servo servo1; //This line create a servo named "servo1"
int buffer; //two more integer variables we will use as buffers
const int pingPin = 3, led = 4; //This is an variable we are setting to 3 and 4 to make it easier to read/write from those pins

void setup() {
  servo1.attach(2); //set the servo to pin 2
  pinMode(led, OUTPUT); //set the led pin as an output
  Serial.begin(9600); // initialize serial communication, this will let us read/write data back and forth (this is useful for debugging)
}

void loop()
{
  long duration, inches; // establish variables for duration of the ping, and the distance result in inches

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);

  pinMode(pingPin, INPUT); //Set the pingPin to an input to read from
  inches = pulseIn(pingPin, HIGH)/ 74 / 2; //read from the pin, divide by 74 to account for the speed of sound, then by 2 to account for the return trip)

  if (inches<20) flusher(); //if the reading is less than 20 start the flush function
  else //if the reading is not less than 20
  {
    buffer--; //decrease the buffer
    if (buffer<0) buffer=0; //make sure the buffer cant be less than 0
    servo1.write(360); //put the servo in the far right position
    digitalWrite(led, LOW); //turn off the LED
  }
  delay(100); //wait a 10th of a second before checking again
}

void flusher()
{
  buffer++; //increase the buffer counter
  if (buffer>15) //if the buffer counter is over 15 (which would be 1500 or 1.5 seconds)
  {
    servo1.write(41); //put the servo in the far left position
    digitalWrite(led, HIGH); //turn the led on
    delay(1000); //wait one second
    servo1.write(360); //put the servo in the far right position
    delay(3000); //wait 3 second
    buffer=0; //reset the buffer
  }
}