// Constants for IR sensor and reset button pins
const int irSensorPin = 5;       // Input pin for MH IR sensor
const int resetButtonPin = 4;    // Input pin for the reset button

// Constants for 7-segment display pins
int digitPins[] = {2, 3, 4}; 
int segmentPins[] = {6, 7, 8, 9, 10, 11, 12, 13}; 

// Number-to-segment mapping
int numbers[][7] = {
  {0, 0, 0, 0, 0, 0, 1}, // zero
  {1, 0, 0, 1, 1, 1, 1}, // one
  {0, 0, 1, 0, 0, 1, 0}, // two
  {0, 0, 0, 0, 1, 1, 0}, // three
  {1, 0, 0, 1, 1, 0, 0}, // four
  {0, 1, 0, 0, 1, 0, 0}, // five
  {0, 1, 0, 0, 0, 0, 0}, // six
  {0, 0, 0, 1, 1, 1, 1}, // seven
  {0, 0, 0, 0, 0, 0, 0}, // eight
  {0, 0, 0, 0, 1, 0, 0}, // nine
};

// Variables
int count = 0;             // Counter value
int lastIrState = LOW;     // Previous state of the IR sensor
int resetButtonState;      // Current state of the reset button
int lastButtonState = LOW; // Previous state of the reset button

unsigned long lastDebounceTime = 0;  // Last debounce time
const unsigned long debounceDelay = 50; // Debounce delay (in ms)

// Initialize pins
void initializePins() {
  pinMode(irSensorPin, INPUT);
  pinMode(resetButtonPin, INPUT);

  for (int i = 0; i < 7; i++) {
    pinMode(segmentPins[i], OUTPUT);
  }

  for (int i = 0; i < 3; i++) {
    pinMode(digitPins[i], OUTPUT);
  }
}

// Turn off all segments of the display
void turnOffDisplay() {
  for (int i = 0; i < 7; i++) {
    digitalWrite(segmentPins[i], HIGH); // Turn off segment (active low)
  }
}

// Display a number on a specific digit
void displayNumber(int number, int digitPin) {
  digitalWrite(digitPins[digitPin], HIGH); // Enable the digit

  for (int i = 0; i < 7; i++) {
    digitalWrite(segmentPins[i], numbers[number][i]);
  }

  delay(5); // Small delay for stability
  digitalWrite(digitPins[digitPin], LOW); // Disable the digit
  turnOffDisplay(); // Turn off the segments
}

// Display the counter value across 3 digits
void displayToThreeDigit(int num) {
  int hundreds = num / 100;       // Extract hundreds place
  int tens = (num / 10) % 10;     // Extract tens place
  int ones = num % 10;            // Extract ones place

  displayNumber(hundreds, 0);     // Display hundreds digit
  displayNumber(tens, 1);         // Display tens digit
  displayNumber(ones, 2);         // Display ones digit
}

// Increment the counter using the IR sensor
void incrementCounter() {
  int currentIrState = digitalRead(irSensorPin);

  // Check if IR sensor detects motion and the state changed from LOW to HIGH
  if (currentIrState == HIGH && lastIrState == LOW) {
    if (count < 20) { // Increment counter only if below 20
      count++;
    }
  }

  lastIrState = currentIrState; // Update the last state
}

// Reset the counter using the button
void resetCounter() {
  int reading = digitalRead(resetButtonPin);

  // Debounce the button input
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != resetButtonState) {
      resetButtonState = reading;

      // Reset the counter if the button is pressed
      if (resetButtonState == HIGH) {
        count = 0;
      }
    }
  }

  lastButtonState = reading;
}

void setup() {
  initializePins();
  turnOffDisplay();
  Serial.begin(9600);
}

void loop() {
  incrementCounter();    // Increment counter using IR sensor
  resetCounter();        // Reset counter using button
  displayToThreeDigit(count); // Display the counter on the 7-segment display
}