Add index property to SMS

Author: sebromero

src/ArduinoCellular.cpp

@@ -272,6 +272,10 @@ SMS parseSMSEntry(const String& entry, const String& message) {
   int fourthQuoteIndex = entry.indexOf('"', thirdQuoteIndex + 1);
   int commaIndexBeforeTimestamp = entry.lastIndexOf(',', entry.lastIndexOf(',') - 1);
 
+  String command = "+CMGL: ";
+  // Index is between "+CMGL: " and first "," symbol
+  sms.index = entry.substring(entry.indexOf(command) + command.length(), entry.indexOf(',')).toInt();
+
   // Extracting number and raw timestamp
   sms.number = entry.substring(thirdQuoteIndex + 1, fourthQuoteIndex);
   String rawTimestamp = entry.substring(commaIndexBeforeTimestamp + 2, entry.indexOf('+', commaIndexBeforeTimestamp) + 3);

src/ArduinoCellular.h

@@ -37,6 +37,7 @@ enum ModemModel {
 class SMS {
     public:
         String number; /**< The phone number associated with the SMS. */
+        int16_t index; /**< The index of the SMS message. */
         String message; /**< The content of the SMS message. */
         Time timestamp; /**< The timestamp when the SMS was received. */
 
@@ -46,18 +47,19 @@ class SMS {
          */
         SMS() {
             this->number = "";
+            this->index = -1;
             this->message = "";
             this->timestamp = Time();
         }
 
         /**
          * Constructor for SMS.
+         * @param index The index of the SMS message.
          * @param number The phone number associated with the SMS.
          * @param message The content of the SMS message.
          * @param timestamp The timestamp when the SMS was received.
          */
-        SMS(String number, String message, Time timestamp) {
-            this->number = number;
+        SMS(int16_t index, String number, String message, Time timestamp) {
             this->message = message;
             this->timestamp = timestamp;
         }