#define ECHO_PIN 2
#define TRIG_PIN 15
#define LED_RED 5
#define LED_ORANGE 21
#define LED_GREEN 25
#define BUZZER_PIN 19  // Only one buzzer pin

const long interval = 1000; // Interval for distance measurements
const unsigned long buzzDuration = 15000; // 15 seconds
const unsigned long cooldownDuration = 1800000; // 30 minutes

unsigned long lastYellowBuzzTime = 0;
unsigned long lastRedBuzzTime = 0;
unsigned long lastCooldownTime = 0;
bool yellowInCooldown = false;
bool redInCooldown = false;

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_ORANGE, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT); // Only one buzzer pin
}

void loop() {
  static unsigned long previousMillis = 0;
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;

    // Trigger the ultrasonic sensor
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);
  
    // Read the echo time
    int duration = pulseIn(ECHO_PIN, HIGH);
    float distance = duration * 0.034 / 2;

    Serial.print("Distance: ");
    Serial.println(distance);

    // Check if cooldowns are over
    if (yellowInCooldown && currentMillis - lastCooldownTime >= cooldownDuration) {
      yellowInCooldown = false;
    }
    if (redInCooldown && currentMillis - lastCooldownTime >= cooldownDuration) {
      redInCooldown = false;
    }

    if (distance > 200) {
      Serial.println("Safe Zone...");
      digitalWrite(LED_GREEN, HIGH);
      digitalWrite(LED_ORANGE, LOW);
      digitalWrite(LED_RED, LOW);
      noTone(BUZZER_PIN);  // Turn off buzzer
    } 
    else if (distance <= 200 && distance > 100) {
      Serial.println("Warning Zone!");
      digitalWrite(LED_GREEN, LOW);
      digitalWrite(LED_ORANGE, HIGH);
      digitalWrite(LED_RED, LOW);

      // Yellow buzzer logic
      if (!yellowInCooldown) {
        tone(BUZZER_PIN, 1000);  // Activate buzzer
        lastYellowBuzzTime = currentMillis;
        yellowInCooldown = true;  // Start cooldown for yellow
        lastCooldownTime = currentMillis;
      }

      // Stop buzzing after 15 seconds
      if (currentMillis - lastYellowBuzzTime >= buzzDuration) {
        noTone(BUZZER_PIN);  // Stop buzzer after 15 seconds
      }
    } 
    else if (distance <= 100) {
      Serial.println("Danger Zone! Alarm Activated!!!");
      digitalWrite(LED_GREEN, LOW);
      digitalWrite(LED_ORANGE, LOW);
      digitalWrite(LED_RED, HIGH);

      // Red buzzer logic
      if (!redInCooldown) {
        tone(BUZZER_PIN, 1000); // Activate buzzer for red zone
        lastRedBuzzTime = currentMillis;
        redInCooldown = true;  // Start cooldown for red
        lastCooldownTime = currentMillis; // Reset cooldown
      }

      // Stop buzzing after 15 seconds
      if (currentMillis - lastRedBuzzTime >= buzzDuration) {
        noTone(BUZZER_PIN);  // Stop buzzer after 15 seconds
      }
    }
  }
}