#include <avr/io.h>
#include <avr/interrupt.h>

const int redPin = 12;    // Red LED connected to digital pin 13
const int yellowPin = 11; // Yellow LED connected to digital pin 12
const int greenPin = 10;  // Green LED connected to digital pin 11
const int buttonRedPin = 2;   // Button for controlling Red LED connected to digital pin 2 (INT0)
const int buttonGreenPin = 3; // Button for controlling Green LED connected to digital pin 3 (INT1)
enum TrafficLightState {
  RED,
  GREEN,
};
TrafficLightState currentState = RED;
void setup() {
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(buttonRedPin, INPUT_PULLUP);   // Enable internal pull-up resistor for buttonRedPin
  pinMode(buttonGreenPin, INPUT_PULLUP); // Enable internal pull-up resistor for buttonGreenPin
  // Configure external interrupts INT0 (pin 2) and INT1 (pin 3)
  EICRA |= (1 << ISC00) | (1 << ISC10); // Set interrupt trigger type to any logical change
  EIMSK |= (1 << INT0) | (1 << INT1);   // Enable external interrupts INT0 and INT1

  // Enable global interrupts
  sei();
}
void loop() {
  // Main loop code goes here
}
// External interrupt INT0 service routine (Button for Red LED)
ISR(INT0_vect) {
  if (currentState != RED) {
    changeState(RED);
  }
}
// External interrupt INT1 service routine (Button for Green LED)
ISR(INT1_vect) {
  if (currentState != GREEN) {
    changeState(GREEN);
  }
}
void changeState(TrafficLightState newState) {
  currentState = newState;
  switch (currentState) {
    case RED:
      digitalWrite(redPin, HIGH);
      digitalWrite(yellowPin, LOW);
      digitalWrite(greenPin, LOW);
      break;
    case GREEN:
      digitalWrite(redPin, LOW);
      digitalWrite(yellowPin, LOW);
      digitalWrite(greenPin, HIGH);
      break;
  }
}