// Pin mapping for 7-segment display (for common cathode)
const int segmentPins[] = {2, 3, 4, 5, 6, 7, 8};  // A, B, C, D, E, F, G
const int digitPins[] = {9, 10, 11};          // DIG1, DIG2, DIG3

// Segment patterns for digits 0-9
const byte digitPatterns[10] = {
  B00111111, // 0
  B00000110, // 1
  B01011011, // 2
  B01001111, // 3
  B01100110, // 4
  B01101101, // 5
  B01111101, // 6
  B00000111, // 7
  B01111111, // 8
  B01101111  // 9
};

// Array to hold the numbers to display on each digit
int initialNumber[3] = {0, 0, 0}; // Initialize with zeros (3 digits)

void setup() {
  Serial.begin(9600); // Start serial communication
  initializeDisplay(); // Call the setup function for the display
  Serial.println("Enter 3-digit number:"); // Initial prompt
}

void loop() {
  updateDisplay(); // Continuously display the numbers on each digit
  readUserInput(); // Check for user input
}

// Function to setup the display
void initializeDisplay() {
  // Set segment pins as output
  for (int i = 0; i < 7; i++) {
    pinMode(segmentPins[i], OUTPUT);
  }

  // Set digit pins as output and turn off all digits initially
  for (int i = 0; i < 4; i++) {
    pinMode(digitPins[i], OUTPUT);
    digitalWrite(digitPins[i], HIGH); // Turn off all digits
  }
}

// Function to display different numbers on each digit
void updateDisplay() {
  for (int i = 0; i < 3; i++) {  // Loop through each digit
    int number = initialNumber[i];  // Get the number for the current digit
    byte segments = digitPatterns[number];  // Get segment pattern for the number
    
    // Set the segments for the current number
    for (int j = 0; j < 7; j++) {
      digitalWrite(segmentPins[j], (segments >> j) & 0x01);  // Set segments
    }
    
    // Activate only the current digit
    digitalWrite(digitPins[i], LOW);  // LOW to turn on the current digit

    // Short delay to allow the digit to stay on
    delay(2);  // 2ms delay for persistence of vision

    // Turn off the current digit before moving to the next
    digitalWrite(digitPins[i], HIGH); // HIGH turns off the digit
  }
}

// Function to check for user input
void readUserInput() {
  if (Serial.available() > 0) {
    String input = Serial.readString(); // Read the input
    input.trim(); // Remove any leading/trailing whitespace

    // Check if the input is exactly 3 digits
    if (input.length() == 3 && input.charAt(0) >= '0' && input.charAt(0) <= '9' &&
        input.charAt(1) >= '0' && input.charAt(1) <= '9' &&
        input.charAt(2) >= '0' && input.charAt(2) <= '9') {
      
      // Fill the initialNumber array with the input
      for (int i = 0; i < 3; i++) {
        initialNumber[i] = input.charAt(i) - '0'; // Convert char to int
      }
      
      Serial.print("Displaying: "); // Print the display numbers to the Serial Monitor
      Serial.println(input);
      Serial.println("Enter 3-digit number:"); // Prompt for next input
    } else {
      Serial.println("Error: Please enter exactly 3 digits.");
      Serial.println("Enter 3-digit number:"); // Prompt for next input
    }
  }
}