/*
   8x8 NeoPixel RTC Clock
   Arduino Nano + DS3231 + WS2812B 64 LED Matrix

   Libraries Required:
   - Adafruit NeoPixel
   - RTClib (by Adafruit)
*/

#include <Wire.h>
#include "RTClib.h"
#include <Adafruit_NeoPixel.h>

#define LED_PIN   D10
#define LED_COUNT 64   // 8x8 matrix

Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
RTC_DS3231 rtc;

// =======================================================

void setup() {
  strip.begin();
  strip.setBrightness(80);
  strip.show();

  if (!rtc.begin()) {
    while (1); // hang if RTC not found
  }

  // Uncomment once to set RTC time to compile time
  // rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
}

// =======================================================

void loop() {
  DateTime now = rtc.now();

  int hours   = now.hour();
  int minutes = now.minute();
  int seconds = now.second();

  strip.clear();

  // Display HH:MM on matrix
  displayDigit(hours / 10, 0);   // tens of hour
  displayDigit(hours % 10, 2);   // ones of hour
  displayDigit(minutes / 10, 5); // tens of minute
  displayDigit(minutes % 10, 7); // ones of minute

  strip.show();
  delay(1000);
}

// =======================================================
// Digit Display (simple bar demo)
// =======================================================

void displayDigit(int num, int col) {
  uint32_t color = strip.Color(0, 150, 255);

  for (int row = 0; row < 8; row++) {
    int idx = matrixIndex(row, col);
    if (row < num) {
      strip.setPixelColor(idx, color);
    }
  }
}

// =======================================================
// Matrix Mapping (serpentine wiring assumed)
// =======================================================

int matrixIndex(int row, int col) {
  if (row % 2 == 0) {
    return row * 8 + col;
  } else {
    return row * 8 + (7 - col);
  }
}