// Pin Definitions
const int interruptPin = 2; // Shared interrupt pin
const int upButton = 3;
const int downButton = 4;
const int selectButton = 5;
const int backButton = 6;

const int ledUp = 10;     // LED for "Up"
const int ledDown = 11;   // LED for "Down"
const int ledSelect = 12; // LED for "Select"
const int ledBack = 13;   // LED for "Back"

// Variables for button states
volatile bool upPressed = false;
volatile bool downPressed = false;
volatile bool selectPressed = false;
volatile bool backPressed = false;

void setup() {
  pinMode(interruptPin, INPUT_PULLUP); // Shared interrupt pin with pull-up
  pinMode(upButton, INPUT_PULLUP);
  pinMode(downButton, INPUT_PULLUP);
  pinMode(selectButton, INPUT_PULLUP);
  pinMode(backButton, INPUT_PULLUP);

  pinMode(ledUp, OUTPUT);      // LED pins set as output
  pinMode(ledDown, OUTPUT);
  pinMode(ledSelect, OUTPUT);
  pinMode(ledBack, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(interruptPin), handleButtonsISR, CHANGE);
  Serial.begin(9600); // Start Serial Monitor
}

void loop() {
  // Handle actions based on button flags
  if (upPressed) {
    handleUp();
    upPressed = false; // Reset the flag
  }

  if (downPressed) {
    handleDown();
    downPressed = false;
  }

  if (selectPressed) {
    handleSelect();
    selectPressed = false;
  }

  if (backPressed) {
    handleBack();
    backPressed = false;
  }

  // Other main loop tasks...
}

void handleButtonsISR() {
  // Debounce delay
  static unsigned long lastInterruptTime = 0;
  unsigned long currentTime = millis();
  if (currentTime - lastInterruptTime < 50) return;
  lastInterruptTime = currentTime;

  // Read button states and set flags
  if (!digitalRead(upButton)) {
    upPressed = true;
  } else if (!digitalRead(downButton)) {
    downPressed = true;
  } else if (!digitalRead(selectButton)) {
    selectPressed = true;
  } else if (!digitalRead(backButton)) {
    backPressed = true;
  }
}

// Function definitions
void handleUp() {
  Serial.println("Up Button Pressed");
  digitalWrite(ledUp, HIGH);  // Turn on the LED
  delay(500);                // Keep the LED on for a short duration
  digitalWrite(ledUp, LOW);   // Turn off the LED
}

void handleDown() {
  Serial.println("Down Button Pressed");
  digitalWrite(ledDown, HIGH);  // Turn on the LED
  delay(500);                  // Keep the LED on for a short duration
  digitalWrite(ledDown, LOW);   // Turn off the LED
}

void handleSelect() {
  Serial.println("Select Button Pressed");
  digitalWrite(ledSelect, HIGH);  // Turn on the LED
  delay(500);                    // Keep the LED on for a short duration
  digitalWrite(ledSelect, LOW);   // Turn off the LED
}

void handleBack() {
  Serial.println("Back Button Pressed");
  digitalWrite(ledBack, HIGH);  // Turn on the LED
  delay(500);                  // Keep the LED on for a short duration
  digitalWrite(ledBack, LOW);   // Turn off the LED
}