#define TRIG_PIN 14  // Pin connected to TRIGGER pin of HC-SR04
#define ECHO_PIN 12  // Pin connected to ECHO pin of HC-SR04

#define MEASUREMENT_INTERVAL 1000 // 1 second in milliseconds
#define SUMMARY_INTERVAL 600000   // 10 minutes in milliseconds

long lastMeasurementMillis = 0;
long lastSummaryMillis = 0;

float totalDistance = 0;
float maxDistance = 0;
float minDistance = 400;  
int numMeasurements = 0;

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

void loop() {
  //Check and see if its time for another measurement
  if (millis() - lastMeasurementMillis >= MEASUREMENT_INTERVAL) {
    float distance = readDistance();
    totalDistance += distance;
    if (distance > maxDistance) {
      maxDistance = distance;
    }
    if (distance < minDistance) {
      minDistance = distance;
    }
    numMeasurements++;
    lastMeasurementMillis = millis();
  }

  if (millis() - lastSummaryMillis >= SUMMARY_INTERVAL) {
    printSummary();
    lastSummaryMillis = millis();
  }
//When "s" is typed into serial command line, print the summary
  if (Serial.available()) {
    char command = Serial.read();
    if (command == 's') {
      printSummary();
    }
  }
}
//Use digitalWrite to initiate pins and read distance
float readDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  float time = pulseIn(ECHO_PIN, HIGH);
  // Distance = (Time * Speed of Sound) / 2
  // Speed of Sound = 343 m/s = 34300 cm/s
  float distance = (time * 0.0343) / 2;

  return distance;
}
//Print all summary information
void printSummary() {
  Serial.println("Summary:");
  Serial.print("Average Distance over the last 10 minutes: ");
  Serial.print(totalDistance / numMeasurements);
  Serial.println(" cm");
  Serial.print("Maximum Distance: ");
  Serial.print(maxDistance);
  Serial.println(" cm");
  Serial.print("Minimum Distance: ");
  Serial.print(minDistance);
  Serial.println(" cm");
  Serial.print("Overall Average Distance: ");
  Serial.print(totalDistance / numMeasurements);
  Serial.println(" cm");
  
  // Resetting values for the next 10 minutes interval
  totalDistance = 0;
  maxDistance = 0;
  minDistance = 400;
  numMeasurements = 0;
}