#define echoPin 6
#define trigPin 7
#define buzzerPin 8

#define INT32MAX 0x7fff
#define SOUND_SPEED 34320 

#define MAX_RANGE 70
#define MIN_RANGE 5


int LOWER = INT32MAX;
int HIGER = 0;

bool forward, backward;
unsigned long period_start;

struct deney{
  int MAX;
  int MIN;
  int period;
};

deney arr_period[256];
int arr_counter = 0;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  Serial.begin(9600);
}

int get_distance(){
  float duration, distance, distance2;

  digitalWrite(trigPin,LOW);
  delayMicroseconds(5);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * SOUND_SPEED/2000000;
  return (int)(distance);
}


void print_all_times(){
  for (int k = 0; k < arr_counter; k++){
    String time_to_press = String(k + 1, DEC) + ". time(ms): ";
    time_to_press += String(arr_period[k].period, DEC);
    Serial.println(time_to_press);
  } 
}

int last_distance = 0;

void loop() {
  	delay(200);
    int distance = get_distance();
    if (!distance){return;}
    if (!last_distance){last_distance = distance;};
  	if (abs(last_distance - distance) <= 1){return;}
    if (!period_start && !forward && !backward){
        period_start = millis();
    }
    if (!forward){
        if (distance < LOWER){
            LOWER = distance;
        }
        if (last_distance < distance){
            forward = true;
        }
    }
    if (!backward){
        if (distance > HIGER){
            HIGER = distance;
        }
        if (last_distance > distance){
            backward = true;
        } 
    }
    last_distance = distance;
    if (forward && backward){
        int period = millis()- period_start;
        if (period > 100){
            String time_to_press = "min: " + String(LOWER, DEC) + " max: " + String(HIGER, DEC) + " period: ";
            Serial.print(time_to_press);
            Serial.println(((float)period / 1000));
        }
        LOWER = INT32MAX;
        HIGER = 0; 
        forward = false;
        backward = false;
        period_start = 0;
        last_distance = 0;
    }
    
}