#include <WiFi.h>
#include <Wire.h>
#include <RTClib.h>
#include <NTPClient.h>
#include <WiFiUdp.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Wi-Fi Credentials
const char* ssid = "Harsh";       // Replace with your Wi-Fi SSID
const char* password = "9879879870";   // Replace with your Wi-Fi password

// RTC and NTP Setup
RTC_DS3231 rtc;           // Create RTC object
WiFiUDP ntpUDP;           // UDP object for NTP client
NTPClient timeClient(ntpUDP, "pool.ntp.org", 19800, 60000);  // UTC+5:30 offset for India (19800 sec)

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

// Function Prototypes
void updateRTCFromNTP();

void setup() {
  Serial.begin(115200);

  // Initialize I2C Communication and RTC
  Wire.begin();
  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC. Check connections!");
    while (1);
  }

  // Check if RTC lost power
  if (rtc.lostPower()) {
    Serial.println("RTC lost power, setting default time.");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__))); // Set to compile time
  }

  // Initialize Wi-Fi
  Serial.println("Connecting to Wi-Fi...");
  WiFi.begin(ssid, password);
  unsigned long startAttemptTime = millis();

  // Wait for Wi-Fi connection or timeout after 10 seconds
  while (WiFi.status() != WL_CONNECTED && millis() - startAttemptTime < 10000) {
    delay(500);
    Serial.print(".");
  }

  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nWi-Fi Connected!");
    timeClient.begin();
    timeClient.update();

    // Update RTC with NTP time
    updateRTCFromNTP();
  } else {
    Serial.println("\nWi-Fi not connected, using RTC time.");
  }

  // Initialize OLED display
  if (!display.begin(SSD1306_I2C_ADDRESS, OLED_RESET)) {
    Serial.println(F("SSD1306 allocation failed"));
    while (1);
  }
  display.display();
  delay(2000);  // Pause for 2 seconds
  display.clearDisplay();
}

void loop() {
  // Fetch current time from RTC
  DateTime now = rtc.now();

  // Display current date and time on Serial Monitor
  Serial.print("Date: ");
  Serial.print(now.day());
  Serial.print("/");
  Serial.print(now.month());
  Serial.print("/");
  Serial.print(now.year());

  Serial.print("  Time: ");
  Serial.print(now.hour());
  Serial.print(":");
  Serial.print(now.minute());
  Serial.print(":");
  Serial.println(now.second());

  // Display current date and time on OLED
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  
  // Print Date
  display.print("Date: ");
  display.print(now.day());
  display.print("/");
  display.print(now.month());
  display.print("/");
  display.println(now.year());

  // Print Time
  display.print("Time: ");
  display.print(now.hour());
  display.print(":");
  display.print(now.minute());
  display.print(":");
  display.println(now.second());

  display.display();  // Update the OLED with new data
  
  delay(1000);  // Update every second
}

void updateRTCFromNTP() {
  Serial.println("Updating RTC with NTP time...");

  timeClient.update();  // Update NTP client to fetch the latest time

  // Get epoch time and set RTC
  unsigned long epochTime = timeClient.getEpochTime();
  rtc.adjust(DateTime(epochTime));  // Update RTC with current time

  Serial.println("RTC successfully updated from NTP!");
}