// Pin assignments for segments (A to G + optional DP)
const int segmentPins[] = {2, 3, 4, 5, 6, 7, 8, 9}; // DP is on Pin 9
const int digitPins[] = {10, 11, 12};               // Common pins for each digit (hundreds, tens, units)

// Number patterns for segments (bit patterns for 0-9)
const byte numberPatterns[] = {
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
  0b00000111, // 7
  0b01111111, // 8
  0b01101111  // 9
};

const int multiplexDelay = 5; // Delay for multiplexing

void setup() {
  Serial.begin(9600);         // Initialize Serial communication
  initializePins();           // Initialize all pins as outputs
}

void loop() {
  int number = getValidThreeDigitNumber(); // Get a valid 3-digit number from user
  Serial.print("Showing on 3 Digits Seven-Segment Display: ");
  Serial.println(number);

  // Continuously display the entered number
  while (true) {
    displayNumber(number);
  }
}

// Function to prompt user until they enter a valid 3-digit number (001-999)
int getValidThreeDigitNumber() {
  int number;
  Serial.println("Please enter a THREE DIGIT number:"); // Prompt only once initially
  while (true) { // Loop until a valid 3-digit number is entered
    while (Serial.available() == 0);      // Wait for user input
    number = Serial.parseInt();           // Read the entered number as an integer

    if (number >= 001 && number <= 999) { // Check if it's a valid 3-digit number
      return number;                      // Return the valid number
    } else {
      // Clear the input buffer before retrying to prevent multiple error messages
      while (Serial.available() > 0) {
        Serial.read(); // Clear any leftover characters in the buffer
      }
      Serial.println("??? YOU DID NOT TYPE A 3 DIGIT NUMBER!!!! TRY AGAIN!!! (001-999)");
      clearAllDigits();                   // Clear the display if input is invalid
    }
  }
}

// Function to initialize all segment and digit pins as outputs
void initializePins() {
  for (int i = 0; i < 8; i++) {
    pinMode(segmentPins[i], OUTPUT);
  }
  for (int i = 0; i < 3; i++) {
    pinMode(digitPins[i], OUTPUT);
  }
}

// Function to display a 3-digit number on the three-digit 7-segment display
void displayNumber(int number) {
  int hundreds = (number / 100) % 10;
  int tens = (number / 10) % 10;
  int units = number % 10;

  showDigit(hundreds, 0);
  showDigit(tens, 1);
  showDigit(units, 2);
}

// Function to show a single digit at a specific position
void showDigit(int digit, int position) {
  clearAllDigits();                    // Turn off all digits before activating the current one
  setSegments(digit);                  // Set the segments for the specified digit
  digitalWrite(digitPins[position], HIGH); // Activate the specified digit position
  delay(multiplexDelay);               // Small delay for multiplexing stability
  digitalWrite(digitPins[position], LOW);  // Turn off the digit after displaying it
}

// Function to set the segments for a specific digit (0-9)
void setSegments(int number) {
  byte pattern = numberPatterns[number];
  for (int i = 0; i < 7; i++) {
    digitalWrite(segmentPins[i], pattern & (1 << i) ? LOW : HIGH); // LOW to turn on for common anode
  }
  digitalWrite(segmentPins[7], HIGH);  // Keep DP off
}

// Function to turn off all digits
void clearAllDigits() {
  for (int i = 0; i < 3; i++) {
    digitalWrite(digitPins[i], LOW);
  }
}