//transforme chaine 'Tue, 16 Dec 2025 23:16:38 GMT' au format heure UTC/greenwitch en un format time_t au fuseau horaire local
time_t parseRFC1123(const char* s) {
  struct tm tm;
  memset(&tm, 0, sizeof(tm));
  char js[5] = {0};
  char monthStr[4] = {0};
  if (sscanf(s, "%s %d %s %d %d:%d:%d", &js, &tm.tm_mday, &monthStr, &tm.tm_year, &tm.tm_hour , &tm.tm_min, &tm.tm_sec) != 7) return 0;
  tm.tm_year -= 1900;
  static const char* months = "JanFebMarAprMayJunJulAugSepOctNovDec";
  const char* p = strstr(months, monthStr);
  if (!p) return -1;
  tm.tm_mon = (p - months) / 3;
  const char* oldTZ = getenv("TZ"); // IMPORTANT : on a un timestamp UTC → utiliser mktime en mode UTC 
  char backup[64] = {0};
  if (oldTZ) strncpy(backup, oldTZ, sizeof(backup)-1);
  setenv("TZ", "UTC", 1);// On force temporairement TZ=UTC
  tzset();
  time_t t = mktime(&tm);
  if (oldTZ) // Restaurer TZ précédent
    setenv("TZ", backup, 1);
  else
    unsetenv("TZ");
  tzset();
  return t;
}


void setup() {
  setenv("TZ", "CET-1CEST,M3.5.0/2,M10.5.0/3", 1);  // équivalent, en plus court de : CET-1CEST-2,M3.5.0/02:00:00,M10.5.0/03:00:00
  tzset();
  Serial.begin(115200);
  struct tm timeinfo;

  getLocalTime(&timeinfo);
  Serial.println(timeinfo.tm_year);

  // Formatage personnalisé : %d=jour, %m=mois, %Y=année, %H=heure, %M=minute, %S=seconde
  Serial.println(&timeinfo, "%d/%m/%Y %H:%M:%S");


  String line = "Date: Tue, 25 Dec 2025 12:44:26 GMT";
  if (line.indexOf("Date: ") != 0) Serial.println("Fail 1");
  time_t utc = parseRFC1123(line.substring(6, 31).c_str());
  Serial.println(utc);
  struct timeval tv = { .tv_sec = utc };
  settimeofday(&tv, NULL);

  if(!getLocalTime(&timeinfo)){
    Serial.println("Erreur : Impossible d'obtenir l'heure");
  }

  // Formatage personnalisé : %d=jour, %m=mois, %Y=année, %H=heure, %M=minute, %S=seconde
  Serial.println(&timeinfo, "%d/%m/%Y %H:%M:%S");

  Serial.println(1900 + timeinfo.tm_year);

}

void loop() {
  delay(10);
}