const int redLEDPin = 13; // Red LED pin
const int greenLEDPin = 7; // Green LED pin
const int pushbuttonPin = 4; // Pushbutton pin

int previousState = LOW; // Previous state of pushbutton
int currentState = LOW; // Current state of pushbutton
bool isBlinkingRed = true; // Flag to determine which LED is blinking (Red or Green)

unsigned long lastDebounceTime = 0; // Last time the pushbutton was debounced
const long debounceTime = 50; // Debounce time in milliseconds

void setup() {
  pinMode(redLEDPin, OUTPUT); // Set red LED pin as output
  pinMode(greenLEDPin, OUTPUT); // Set green LED pin as output
  pinMode(pushbuttonPin, INPUT_PULLUP); // Set pushbutton pin as input with pull-up resistor
}

void loop() {
  currentState = digitalRead(pushbuttonPin); // Read current state of pushbutton

  // Debounce pushbutton to eliminate bouncing effect
  if (currentState != previousState) {
    unsigned long currentTime = millis();
    if (currentTime - lastDebounceTime >= debounceTime) {
      lastDebounceTime = currentTime;
      if (currentState == HIGH) { // If pushbutton is pressed
        if (isBlinkingRed) { // If red LED is blinking, switch to blinking green
          isBlinkingRed = false;
        } else { // If green LED is blinking, switch to blinking red
          isBlinkingRed = true;
        }
      }
    }
  }

  previousState = currentState; // Update previous state

  // Update LEDs based on blinking state
  if (isBlinkingRed) {
    digitalWrite(redLEDPin, HIGH); // Turn on red LED
    digitalWrite(greenLEDPin, LOW); // Turn off green LED
  } else {
    digitalWrite(redLEDPin, LOW); // Turn off red LED
    digitalWrite(greenLEDPin, HIGH); // Turn on green LED
  }

  // Blink the active LED
  if (isBlinkingRed) {
    delay(500); // Blink red LED at 0.5 Hz
    digitalWrite(redLEDPin, LOW);
  } else {
    delay(500); // Blink green LED at 0.5 Hz
    digitalWrite(greenLEDPin, LOW);
  }
}