#define ECHO_PIN 2
#define TRIG_PIN 15
#define LED_RED 5
#define LED_ORANGE 21
#define LED_GREEN 25
#define BUZZER_PIN_1 19
#define BUZZER_PIN_2 12

unsigned long previousMillis = 0; // Store the last time we updated the readings
const long interval = 1000;        // Interval for distance measurements

unsigned long buzzerStartMillis = 0; // Start time for the buzzer
const unsigned long buzzerDuration = 15000; // Duration to buzz in milliseconds (15 seconds)
const unsigned long cooldownDurationYellow = 1800000; // Cooldown duration in milliseconds for yellow (30 minutes)
bool isBuzzingYellow = false; // State to track if the yellow buzzer is currently buzzing
bool isBuzzingRed = false; // State to track if the red buzzer is currently buzzing
bool isCoolingDownYellow = false; // State to track if the yellow buzzer is in cooldown
bool isCoolingDownRed = false; // State to track if the red buzzer is in cooldown
unsigned long cooldownStartMillisYellow = 0; // Start time for yellow cooldown
unsigned long cooldownStartMillisRed = 0; // Start time for red cooldown

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_1, OUTPUT);
  pinMode(BUZZER_PIN_2, OUTPUT);
}

void loop() {
  unsigned long currentMillis = millis(); // Get the current time

  // Check if it's time to take a distance reading
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis; // Save the last time we measured

    // 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;  // Calculate distance in cm
  
    Serial.print("Distance: ");
    Serial.println(distance);

    // Check distance and activate corresponding outputs
    if (distance > 200) {
      Serial.println("Safe Zone...");
      digitalWrite(LED_GREEN, HIGH);
      digitalWrite(LED_ORANGE, LOW);
      digitalWrite(LED_RED, LOW);
      noTone(BUZZER_PIN_1);
      noTone(BUZZER_PIN_2);
      isBuzzingYellow = false; // Reset the yellow buzzer state
      isBuzzingRed = false; // Reset the red buzzer state
    } 
    else if (distance <= 200 && distance > 100) {
      Serial.println("Warning Zone!");
      digitalWrite(LED_GREEN, LOW);
      digitalWrite(LED_ORANGE, HIGH);
      digitalWrite(LED_RED, LOW);
      
      // Only activate the yellow buzzer if it has not buzzed in the last 15 seconds
      if (!isBuzzingYellow && !isCoolingDownYellow) {
        tone(BUZZER_PIN_1, 1000);  // Activate first buzzer at 1000 Hz
        buzzerStartMillis = currentMillis; // Record when buzzing started
        isBuzzingYellow = true; // Set the yellow buzzer state to buzzing
      }
    } 
    else if (distance <= 100) {
      Serial.println("Danger Zone! Alarm Activated!!!");
      digitalWrite(LED_GREEN, LOW);
      digitalWrite(LED_ORANGE, LOW);
      digitalWrite(LED_RED, HIGH);
      
      // Activate the red buzzer if it has not buzzed yet
      if (!isBuzzingRed) {
        tone(BUZZER_PIN_2, 1000); // Activate second buzzer at 1000 Hz
        buzzerStartMillis = currentMillis; // Record when buzzing started
        isBuzzingRed = true; // Set the red buzzer state to buzzing
      }
    }
  }

  // Check if the yellow buzzer duration has elapsed
  if (isBuzzingYellow && (currentMillis - buzzerStartMillis >= buzzerDuration)) {
    noTone(BUZZER_PIN_1); // Turn off the yellow buzzer after 15 seconds
    isBuzzingYellow = false; // Reset the yellow buzzer state
    isCoolingDownYellow = true; // Start cooldown period for yellow
    cooldownStartMillisYellow = currentMillis; // Record when cooldown started
  }

  // Check if the red buzzer should be stopped (only if it was activated)
  if (isBuzzingRed && (currentMillis - buzzerStartMillis >= buzzerDuration)) {
    noTone(BUZZER_PIN_2); // Turn off the red buzzer after 15 seconds
    isBuzzingRed = false; // Reset the red buzzer state
    isCoolingDownRed = true; // Start cooldown period for red
    cooldownStartMillisRed = currentMillis; // Record when cooldown started
  }

  // Manage cooldown for yellow buzzer
  if (isCoolingDownYellow && (currentMillis - cooldownStartMillisYellow >= cooldownDurationYellow)) {
    isCoolingDownYellow = false; // Reset cooldown state for yellow
  }

  // Manage cooldown for red buzzer (not affecting yellow)
  if (isCoolingDownRed && (currentMillis - cooldownStartMillisRed >= cooldownDurationYellow)) {
    isCoolingDownRed = false; // Reset cooldown state for red
  }
}