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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

RTC_DS1307 rtc;

bool zoomIn = true;

void setup() {
  Serial.begin(9600);

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("OLED allocation failed"));
    while (true);
  }

  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (true);
  }

  if (!rtc.isrunning()) {
    Serial.println("RTC not running, setting time...");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }

  display.clearDisplay();
  display.display();
}

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

  // Format: HH:MM:SS (8 characters + null terminator)
  char timeStr[9];
  sprintf(timeStr, "%02d:%02d:%02d", now.hour(), now.minute(), now.second());

  // Toggle zoom: size 1 or 2 only
  int textSize = zoomIn ? 2 : 1;
  zoomIn = !zoomIn;

  display.clearDisplay();
  display.setTextSize(textSize);
  display.setTextColor(SSD1306_WHITE);

  // Calculate bounding box to center text
  int16_t x1, y1;
  uint16_t w, h;
  display.getTextBounds(timeStr, 0, 0, &x1, &y1, &w, &h);

  int x = (SCREEN_WIDTH - w) / 2;
  int y = (SCREEN_HEIGHT - h) / 2;

  display.setCursor(x, y);
  display.print(timeStr);
  display.display();

  delay(1000);
}