/*
   ESP32-C3 Mini + DS3231 RTC
   SSD1306 OLED Digital Clock

   Libraries Required:
   - Adafruit SSD1306
   - Adafruit GFX
   - RTClib
*/

#include <Wire.h>
#include "RTClib.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED width
#define SCREEN_HEIGHT 64 // OLED height
#define OLED_RESET    -1 // Reset pin not used

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
RTC_DS3231 rtc;

void setup() {
  // Initialize I2C for ESP32-C3 Mini (SDA=GPIO6, SCL=GPIO7)
  Wire.begin(4, 5);

  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    while (1); // hang if OLED not found
  }
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  // Initialize RTC
  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();

  display.clearDisplay();

  // Large digital clock display
  display.setTextSize(3); // big font
  display.setCursor(0, 10);
  if (hours < 10) display.print("0");
  display.print(hours);
  display.print(":");
  if (minutes < 10) display.print("0");
  display.print(minutes);

  // Seconds in smaller font
  display.setTextSize(2);
  display.setCursor(90, 40);
  if (seconds < 10) display.print("0");
  display.print(seconds);

  display.display();
  delay(1000);
}