#include <Arduino.h>
#include <WiFi.h>
#include "time.h"
#include "esp_sntp.h"

const char *ssid = "YOUR_SSID";
const char *password = "YOUR_PASS";

const char *ntpServer1 = "pool.ntp.org";
const char *ntpServer2 = "time.nist.gov";
const long gmtOffset_sec = 3600;
const int daylightOffset_sec = 3600;

const char *time_zone = "CET-1CEST,M3.5.0,M10.5.0/3";  // TimeZone rule for Europe/Rome including daylight adjustment rules (optional)

void printLocalTime() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    Serial.println("No time available (yet)");
    return;
  }
  Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
}

// Callback function (gets called when time adjusts via NTP)
void timeavailable(struct timeval *t) {
  Serial.println("Got time adjustment from NTP!");
  printLocalTime();
}

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

  // First step is to configure WiFi STA and connect in order to get the current time and date.
  Serial.printf("Connecting to %s ", ssid);
  WiFi.begin(ssid, password);

  /**
   * NTP server address could be acquired via DHCP,
   *
   * NOTE: This call should be made BEFORE esp32 acquires IP address via DHCP,
   * otherwise SNTP option 42 would be rejected by default.
   * NOTE: configTime() function call if made AFTER DHCP-client run
   * will OVERRIDE acquired NTP server address
   */
  esp_sntp_servermode_dhcp(1);  // (optional)

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" CONNECTED");

  // set notification call-back function
  sntp_set_time_sync_notification_cb(timeavailable);

  /**
   * This will set configured ntp servers and constant TimeZone/daylightOffset
   * should be OK if your time zone does not need to adjust daylightOffset twice a year,
   * in such a case time adjustment won't be handled automagically.
   */
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer1, ntpServer2);

  /**
   * A more convenient approach to handle TimeZones with daylightOffset
   * would be to specify a environment variable with TimeZone definition including daylight adjustmnet rules.
   * A list of rules for your zone could be obtained from https://github.com/esp8266/Arduino/blob/master/cores/esp8266/TZ.h
   */
  //configTzTime(time_zone, ntpServer1, ntpServer2);
}

void loop() {
  delay(5000);
  printLocalTime();  // it will take some time to sync time :)
}
