/*
  Simple Traffic Light with Emergency Priority
  Emergency works in YELLOW and RED
*/

// LED pins
int redLed    = 10;
int yellowLed = 11;
int greenLed  = 12;

// Input pins
int buttonPin = 2;
int ldrPin    = A0;

// Time settings (milliseconds)
int greenTime  = 5000;
int yellowTime = 2000;
int redTime    = 5000;
int emergencyGreenTime = 7000;

// LDR threshold
int ldrThreshold = 700;

void setup() {
  Serial.begin(9600);
  pinMode(redLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(greenLed, OUTPUT);

  pinMode(buttonPin, INPUT_PULLUP); // button to GND
  Serial.print("LDR Value:");
  Serial.println(analogRead(ldrPin));
}

void loop() {

  // -------- GREEN --------
  digitalWrite(greenLed, HIGH);
  digitalWrite(yellowLed, LOW);
  digitalWrite(redLed, LOW);
  delay(greenTime);

  // -------- YELLOW --------
  digitalWrite(greenLed, LOW);
  digitalWrite(yellowLed, HIGH);
  digitalWrite(redLed, LOW);

  unsigned long startYellow = millis();
  while (millis() - startYellow < yellowTime) {
    Serial.print("LDR Value:");
    Serial.println(analogRead(ldrPin));
    if (isEmergency()) {
      handleEmergency();
      return; // restart normal cycle
    }
  }

  // -------- RED --------
  digitalWrite(greenLed, LOW);
  digitalWrite(yellowLed, LOW);
  digitalWrite(redLed, HIGH);

  unsigned long startRed = millis();
  while (millis() - startRed < redTime) {
    Serial.print("LDR Value:");
    Serial.println(analogRead(ldrPin));
    if (isEmergency()) {
      handleEmergency();
      return; // restart normal cycle
    }
  }
}

/* ---------- Helper Functions ---------- */

// Check emergency condition
bool isEmergency() {
  if (digitalRead(buttonPin) == LOW) return true;
  if (analogRead(ldrPin) > ldrThreshold) return true;
  return false;
}

// Emergency handling
void handleEmergency() {
  digitalWrite(redLed, LOW);
  digitalWrite(yellowLed, LOW);
  digitalWrite(greenLed, HIGH);

  delay(emergencyGreenTime);

  digitalWrite(greenLed, LOW);
}