#include <LedControl.h>

// Pin definitions for the MAX7219
#define DATA_IN   11   // Pin connected to DATA IN of MAX7219
#define LOAD       8   // Pin connected to LOAD of MAX7219
#define CLOCK      13   // Pin connected to CLOCK of MAX7219
#define MAX_DEVICES 4  // Number of 8x8 matrices in the chain

// Initialize LedControl library
LedControl lc = LedControl(DATA_IN, CLOCK, LOAD, MAX_DEVICES);

// Button Pin
const int buttonPin = 7;  // Button connected to pin 2
int buttonState = 0;      // Variable to hold button state
int lastButtonState = 0;  // Variable to remember last button state
unsigned long lastDebounceTime = 0;  // For debouncing the button
unsigned long debounceDelay = 50;    // debounce time (milliseconds)

// Stopwatch time variables
unsigned long startTime = 0;
unsigned long elapsedTime = 0;
bool running = false; // Indicates if the stopwatch is running

void setup() {
  // Set button pin as input
  pinMode(buttonPin, INPUT_PULLUP);

  // Initialize the MAX7219 display
  for (int i = 0; i < MAX_DEVICES; i++) {
    lc.shutdown(i, false);  // Wake up the display
    lc.setIntensity(i, 8);   // Set brightness to middle
    lc.clearDisplay(i);      // Clear display
  }
}

void loop() {
  // Read the button state
  int reading = digitalRead(buttonPin);

  // Check for button press (debouncing)
  if (reading != lastButtonState) {
    lastDebounceTime = millis();  // reset debounce timer
  }

  // If the button state has changed and the debounce delay has passed
  if ((millis() - lastDebounceTime) > debounceDelay) {
    // If the button is pressed (LOW signal, due to INPUT_PULLUP)
    if (reading == LOW && lastButtonState == HIGH) {
      if (running) {
        // Stop the stopwatch and reset it
        running = false;
        elapsedTime = 0;
      } else {
        // Start the stopwatch
        startTime = millis() - elapsedTime;
        running = true;
      }
    }
  }

  // Store the button state for the next loop
  lastButtonState = reading;

  // If the stopwatch is running, update the elapsed time
  if (running) {
    elapsedTime = millis() - startTime;
  }

  // Display the time in seconds (for simplicity)
  unsigned long seconds = elapsedTime / 1000;
  unsigned long minutes = seconds / 60;
  seconds = seconds % 60;

  // Display minutes and seconds on the MAX7219
  displayTime(minutes, seconds);
}

void displayTime(unsigned long minutes, unsigned long seconds) {
  // Split minutes and seconds into digits
  byte digits[4] = {
    map(minutes / 10, 0, 9, 0, 15),  // Tens place of minutes
    map(minutes % 10, 0, 9, 0, 15),  // Ones place of minutes
    map(seconds / 10, 0, 9, 0, 15),  // Tens place of seconds
    map(seconds % 10, 0, 9, 0, 15)   // Ones place of seconds
  };

  // Display each digit on the 4x8 matrices
  for (int i = 0; i < 4; i++) {
    lc.setDigit(i, 0, digits[i], false); // Set the digit on each 8x8 matrix
  }
}