const int trig_pin = 13;
const int echo_pin = 12;
const int ldr_pin = A0;
const int pir_pin = 7;
const int relay_pin = 6;
const int pot_pin = A1;

int ldr_threshold = 500;
int distance_threshold = 200;

int ldr_value;
int pir_value;
int distance;
long duration;
bool relay_state = LOW;
int pot_value;

void setup() {
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  pinMode(pir_pin, INPUT);
  pinMode(relay_pin, OUTPUT);

  Serial.begin(9600);
}

void loop() {
  readUltrasonic();
  readLDR();
  readPIR();
  readPot();
  

  printSensorValuesPC();

  if (ldr_value > ldr_threshold) {
    if (distance < distance_threshold || pir_value == 1) {
      relay_state = HIGH;
    } else {
      relay_state = LOW;
    }
  }

  digitalWrite(relay_pin, relay_state);
}

void  printSensorValuesPC() {
  Serial.print("\tdistance =");
  Serial.print(distance );
  Serial.print("\tldr_value =");
  Serial.print(ldr_value );
  Serial.print("\tldr_threshold =");
  Serial.println(ldr_threshold); 
}

void readPot() {
  ldr_threshold = analogRead(pot_pin);
}

void readPIR() {
  pir_value = digitalRead(pir_pin);
}

void readLDR() {
  ldr_value = analogRead(ldr_pin);
}

void readUltrasonic(){
  digitalWrite(trig_pin, LOW);
  delayMicroseconds(2);
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);

  duration = pulseIn(echo_pin, HIGH);

  distance = 0.017 * duration;
}