// ===== PIN DEFINITIONS =====
#define RED_LED     5
#define YELLOW_LED  4
#define GREEN_LED   2
#define BUZZER      18

#define EMG_BTN     12   // Emergency
#define DENSITY_BTN 14   // Traffic density

#define SCHOOL_BTN  27   // School mode ON/OFF
#define PED_BTN     26   // Pedestrian button
#define ULTRA_BTN   25   // Ultrasonic (student crossed without button)

// ===== SETUP =====
void setup() {
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  pinMode(EMG_BTN, INPUT_PULLUP);
  pinMode(DENSITY_BTN, INPUT_PULLUP);
  pinMode(SCHOOL_BTN, INPUT_PULLUP);
  pinMode(PED_BTN, INPUT_PULLUP);
  pinMode(ULTRA_BTN, INPUT_PULLUP);

  digitalWrite(RED_LED, HIGH);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(BUZZER, LOW);
}

// ===== EMERGENCY MODE =====
void emergencyMode() {
  digitalWrite(RED_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);
  digitalWrite(BUZZER, HIGH);
}

// ===== SCHOOL ZONE MODE =====
void schoolZone() {

  // Yellow blinking warning
  digitalWrite(YELLOW_LED, HIGH);
  delay(300);
  digitalWrite(YELLOW_LED, LOW);
  delay(300);

  // Planned crossing (button pressed)
  if (digitalRead(PED_BTN) == LOW) {
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER, LOW);   // calm crossing
    delay(8000);
  }

  // Emergency child crossing (no button)
  else if (digitalRead(ULTRA_BTN) == LOW) {
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER, HIGH);  // emergency warning
    delay(3000);
    digitalWrite(BUZZER, LOW);
  }
}

// ===== TRAFFIC WITH DENSITY =====
void trafficWithDensity() {

  bool highDensity = (digitalRead(DENSITY_BTN) == LOW);
  int greenTime = highDensity ? 8000 : 3000;

  // RED
  digitalWrite(RED_LED, HIGH);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, LOW);
  delay(3000);

  // GREEN
  digitalWrite(RED_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);
  delay(greenTime);

  // YELLOW
  digitalWrite(RED_LED, LOW);
  digitalWrite(YELLOW_LED, HIGH);
  digitalWrite(GREEN_LED, LOW);
  delay(1500);
}

// ===== LOOP =====
void loop() {

  // 1️⃣ Emergency (TOP PRIORITY)
  if (digitalRead(EMG_BTN) == LOW) {
    emergencyMode();
    while (digitalRead(EMG_BTN) == LOW) {
      delay(10);
    }
    digitalWrite(BUZZER, LOW);
  }

  // 2️⃣ School Zone
  else if (digitalRead(SCHOOL_BTN) == LOW) {
    schoolZone();
  }

  // 3️⃣ Normal traffic with density
  else {
    trafficWithDensity();
  }
}