// Learn about the ESP32 WiFi simulation in
// https://docs.wokwi.com/guides/esp32-wifi
// Derived from Wokwi "ESP32 NTP Clock"
// https://wokwi.com/projects/321525495180034642
// Read https://randomnerdtutorials.com/esp32-ntp-timezones-daylight-saving/
// for more information on using timezones

#include <WiFi.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C LCD = LiquidCrystal_I2C(0x27, 16, 2);

#define NTP_SERVER     "pool.ntp.org"
#define UTC_OFFSET     0
#define UTC_OFFSET_DST 0

void spinner() {
  static int8_t counter = 0;
  const char* glyphs = "\xa1\xa5\xdb";
  LCD.setCursor(15, 1);
  LCD.print(glyphs[counter++]);
  if (counter == strlen(glyphs)) {
    counter = 0;
  }
}

void printLocalTime() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    LCD.setCursor(0, 1);
    LCD.println("Connection Err");
    return;
  }

  LCD.setCursor(8, 0);
  LCD.println(&timeinfo, "%H:%M:%S");

  LCD.setCursor(0, 1);
  LCD.println(&timeinfo, "%Y-%m-%d   %Z");
}

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

  LCD.init();
  LCD.backlight();
  LCD.setCursor(0, 0);
  LCD.print("Connecting to ");
  LCD.setCursor(0, 1);
  LCD.print("WiFi ");

  WiFi.begin("Wokwi-GUEST", "", 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
    spinner();
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  LCD.clear();
  LCD.setCursor(0, 0);
  LCD.println("Online");
  LCD.setCursor(0, 1);
  LCD.println("Updating time...");

  configTime(UTC_OFFSET, UTC_OFFSET_DST, NTP_SERVER);
  setTimezone("CET-1CEST,M3.5.0,M10.5.0/3");
//  initTime("CET-1CEST,M3.5.0,M10.5.0/3"); // TZ-String for Europe/Berlin
}

void loop() {
  int i;
  for (i=0; i<30; i++) {
    printLocalTime();
    delay(1000);
  }

  Serial.println();
  Serial.println("Now change the time.  10 seconds before DST takes effect. (last Sunday of Oct)");
  setTime(2023,10,29,1,59,50,0);    // Set it to 10 seconds before daylight savings comes in.
  
  for(i=0; i<20; i++){
    delay(1000);
    printLocalTime();
  }  
  Serial.println();
  Serial.println("Now change the time. 10 seconds before DST ends. (last Sunday of Mar)");
  setTime(2024,3,31,2,59,50,1);    // Set it to 10 seconds before daylight savings comes in.
  
  for(i=0; i<20; i++){
    delay(1000);
    printLocalTime();
  }  

}


void setTimezone(String timezone){
  Serial.printf("  Setting Timezone to %s\n",timezone.c_str());
  setenv("TZ",timezone.c_str(),1);  //  Now adjust the TZ.  Clock settings are adjusted to show the new local time
  tzset();
}

void setTime(int yr, int month, int mday, int hr, int minute, int sec, int isDst){
  struct tm tm;

  tm.tm_year = yr - 1900;   // Set date
  tm.tm_mon = month-1;
  tm.tm_mday = mday;
  tm.tm_hour = hr;      // Set time
  tm.tm_min = minute;
  tm.tm_sec = sec;
  tm.tm_isdst = isDst;  // 1 or 0
  time_t t = mktime(&tm);
  Serial.printf("Setting time: %s", asctime(&tm));
  struct timeval now = { .tv_sec = t };
  settimeofday(&now, NULL);
}