Refactor time handling adding localtime/utc and ntp sync flags

src/ArduinoCellular.cpp

@@ -5,11 +5,38 @@
   #include "Watchdog.h"
 #endif
 
-unsigned long ArduinoCellular::getTime() {
-    int year, month, day, hour, minute, second;
+Time ArduinoCellular::getTimeStruct(bool localTime) {
+    int year = 1970;
+    int month = 1;
+    int day = 1;
+    int hour = 0;
+    int minute = 0;
+    int second = 0;
     float tz;
-    modem.getNetworkTime(&year, &month, &day, &hour, &minute, &second, &tz);
-    return Time(year, month, day, hour, minute, second).getUNIXTimestamp();
+    if (syncNTPServer() == 0) {
+        if (localTime) {
+            modem.getNetworkTime(&year, &month, &day, &hour, &minute, &second, &tz);
+        } else {
+            modem.getNetworkUTCTime(&year, &month, &day, &hour, &minute, &second, &tz);
+        }
+    }
+    return Time(year, month, day, hour, minute, second);
+}
+
+unsigned long ArduinoCellular::getTime() {
+    return getTimeStruct().getUNIXTimestamp();
+}
+
+int ArduinoCellular::syncNTPServer(bool forceNTPSync) {
+    static bool needNTPSync = true;
+    if(!needNTPSync && !forceNTPSync) {
+        return 0;
+    }
+    if(modem.NTPServerSync() == 0) {
+        needNTPSync = false;
+        return 0;
+    }
+    return -1;
 }
 
 ArduinoCellular::ArduinoCellular() {
@@ -126,20 +153,15 @@ Time ArduinoCellular::getGPSTime(){
     return Time(year, month, day, hour, minute, second);
 }
 
-Time ArduinoCellular::getCellularTime(){
-    int year = 1970;
-    int month = 1;
-    int day = 1;
-    int hour = 0;
-    int minute = 0;
-    int second = 0;
-    float tz;
-    if (modem.NTPServerSync() == 0) {
-      modem.getNetworkTime(&year, &month, &day, &hour, &minute, &second, &tz);
-    }
-    return Time(year, month, day, hour, minute, second);
+Time ArduinoCellular::getCellularTime(bool localTime){
+    // Get the current time from the network as localtime
+    return getTimeStruct(localTime);
 }
 
+bool ArduinoCellular::syncCellularTime(){
+    // Sync the time with the network NTP service
+    return syncNTPServer(true) == 0 ? true : false;
+}
 
 void ArduinoCellular::sendSMS(String number, String message){
     modem.sendAT("+CMGF=1"); 

src/ArduinoCellular.h

@@ -158,12 +158,19 @@ class ArduinoCellular {
          * @return The GPS location. If the location is not retrieved, the latitude and longitude will be 0.0.
          */
         Geolocation getGPSLocation(unsigned long timeout = 60000);
-        
+
         /**
          * @brief Gets the current time from the network.
+         * @param localTime If true, the time will be converted to local time. Default is true.
          * @return The current time.
          */
-        Time getCellularTime();
+        Time getCellularTime(bool localTime = true);
+
+        /**
+         * @brief Sync the modem time using NTP service.
+         * @return True  on success false otherwise.
+         */
+        bool syncCellularTime();
 
         /**
          * @brief Gets the current time from the GPS module.
@@ -303,7 +310,11 @@ class ArduinoCellular {
 
         static unsigned long getTime(); /** Callback for getting the current time as an unix timestamp. */
 
+        static Time getTimeStruct(bool localTime = false); /** Function for getting the current time as a Time object. */
+
         static constexpr unsigned long waitForNetworkTimeout = 20000L; /**< Maximum wait time for network registration (In milliseconds). */
+
+        static int syncNTPServer(bool forceNTPSync = false); /** Function for synchronizing the NTP server. */
 };