#define RED_LED_PIN 17
#define YELLOW_LED_PIN 5
#define GREEN_LED_PIN 18
#define BUTTON_PIN 19

// State variables
enum TrafficLightState { RED, YELLOW, GREEN, GREEN_MANUAL };
TrafficLightState currentState = RED;
unsigned long previousMillis = 0;
const long redInterval = 5000;   // 5 seconds for Red
const long yellowInterval = 4000; // 4 seconds for Yellow
const long greenInterval = 2000;  // 2 seconds for Green
const long greenManualInterval = 15000;  // 15 seconds for Green when button is pressed
unsigned long greenManualStartMillis = 0;  // To track the start time of Green in manual mode

bool buttonPressed = false;  // Flag to track button state
bool greenLedState = false;  // Flag to track the Green LED state (on or off)

void setup() {
  // Initialize LED pins as output
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(YELLOW_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  
  // Initialize button pin as input with pullup resistor
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // Start with Red LED on
  digitalWrite(RED_LED_PIN, HIGH);
  digitalWrite(YELLOW_LED_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
}

void loop() {
  // Read the button state
  int buttonState = digitalRead(BUTTON_PIN);

  // If the button is pressed (active LOW)
  if (buttonState == LOW && !buttonPressed) {
    buttonPressed = true;  // Mark the button as pressed

    // Toggle the Green LED
    if (greenLedState) {
      // Turn off Green LED if it was on
      digitalWrite(RED_LED_PIN, LOW);
      digitalWrite(YELLOW_LED_PIN, LOW);
      digitalWrite(GREEN_LED_PIN, LOW);  // Turn off Green LED
      currentState = RED;  // Return to RED state
      greenLedState = false;  // Set Green LED state to off
    } else {
      // Turn on Green LED for 15 seconds
      digitalWrite(RED_LED_PIN, LOW);
      digitalWrite(YELLOW_LED_PIN, LOW);
      digitalWrite(GREEN_LED_PIN, HIGH);  // Turn on Green LED

      currentState = GREEN_MANUAL;  // Set to manual Green mode
      greenManualStartMillis = millis();  // Start timer for 15 seconds
      greenLedState = true;  // Set Green LED state to on
    }

    delay(200);  // Debounce delay to avoid multiple button presses
  }

  // If the button is released, reset the button pressed flag
  if (buttonState == HIGH) {
    buttonPressed = false;
  }

  // If in manual Green mode, check if 15 seconds have passed
  if (currentState == GREEN_MANUAL) {
    unsigned long currentMillis = millis();
    if (currentMillis - greenManualStartMillis >= greenManualInterval) {
      // After 15 seconds, turn off the Green LED and return to automatic cycling
      digitalWrite(RED_LED_PIN, LOW);
      digitalWrite(YELLOW_LED_PIN, LOW);
      digitalWrite(GREEN_LED_PIN, LOW);  // Turn off Green LED
      currentState = RED;
      greenLedState = false;  // Set Green LED state to off
    }
  }

  // Cycle through the lights automatically if not in manual Green mode
  else {
    // Check the time passed to manage the automatic cycle
    unsigned long currentMillis = millis();

    if (currentState == RED && currentMillis - previousMillis >= redInterval) {
      // Time to change from RED to YELLOW
      previousMillis = currentMillis;
      currentState = YELLOW;
    } 
    else if (currentState == YELLOW && currentMillis - previousMillis >= yellowInterval) {
      // Time to change from YELLOW to GREEN
      previousMillis = currentMillis;
      currentState = GREEN;
    } 
    else if (currentState == GREEN && currentMillis - previousMillis >= greenInterval) {
      // Time to change from GREEN to RED
      previousMillis = currentMillis;
      currentState = RED;
    }

    // Update the traffic light based on the current state
    updateTrafficLight();
  }
}

void updateTrafficLight() {
  // Turn off all LEDs first
  digitalWrite(RED_LED_PIN, LOW);
  digitalWrite(YELLOW_LED_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
  
  // Set the appropriate LED based on the current state
  if (currentState == RED) {
    digitalWrite(RED_LED_PIN, HIGH);
  } else if (currentState == YELLOW) {
    digitalWrite(YELLOW_LED_PIN, HIGH);
  } else if (currentState == GREEN) {
    digitalWrite(GREEN_LED_PIN, HIGH);
  }
}