// Pin Definitions
const int redLED = 14;
const int yellowLED = 27;
const int greenLED = 26;
const int buzzer = 25;
const int buttonPin = 4;
const int triggerPin = 5; // Ultrasonic sensor trigger
const int echoPin = 18;   // Ultrasonic sensor echo

void setup() {
  // Initialize Serial Monitor
  Serial.begin(115200);
  Serial.println("System Initializing...");

  // Set Pin Modes
  pinMode(redLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);

  Serial.println("Setup Complete.");
}

void loop() {
  // Traffic Light Sequence
  trafficLightControl();

  // Check Emergency Button
  if (digitalRead(buttonPin) == LOW) {
    emergencyAlert();
  }

  delay(100);
}

void trafficLightControl() {
  int trafficDensity = detectTraffic(); // Measure traffic density
  Serial.print("Traffic Density: ");
  Serial.println(trafficDensity);

  // Red Light ON
  digitalWrite(redLED, HIGH);
  Serial.println("Red Light ON");
  delay(5000);

  // Green Light ON
  digitalWrite(redLED, LOW);
  digitalWrite(greenLED, HIGH);
  Serial.println("Green Light ON");
  delay(trafficDensity > 50 ? 10000 : 5000); // Adaptive timing based on traffic density

  // Yellow Light ON
  digitalWrite(greenLED, LOW);
  digitalWrite(yellowLED, HIGH);
  Serial.println("Yellow Light ON");
  delay(2000);

  digitalWrite(yellowLED, LOW);
}

int detectTraffic() {
  // Measure distance using Ultrasonic Sensor
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2; // Convert to centimeters

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

  // Return traffic density score
  if (distance < 30) {
    Serial.println("High Traffic Detected!");
    return 70; // High traffic density
  } else {
    Serial.println("Low Traffic Detected.");
    return 20; // Low traffic density
  }
}

void emergencyAlert() {
  Serial.println("Emergency Alert Triggered!");
  digitalWrite(buzzer, HIGH); // Turn on buzzer
  delay(1000);
  digitalWrite(buzzer, LOW);  // Turn off buzzer
}