#include <SoftwareSerial.h>

#define rxPin 7
#define txPin 8
SoftwareSerial mySerial = SoftwareSerial(rxPin, txPin);

// EN: String buffer for the GPRS shield message
String SmsStorePos = String("");
String msg = String("");
String snTmp = String("");
String snFull = String("");

// EN: Set to 1 when the next GPRS shield message will contains the SMS message
int SmsContentFlag = 0;

// EN: Pin of the LED to turn ON and OFF depending on the received message
int ledPin = 5;
int powerPin = 6;

void setup()
{
  mySerial.begin(115200);               // the GPRS baud rate  
  mySerial.print("\
");
  delay(1000);
  Serial.begin(115200);                 // the Arduino IDE serial
  Serial.println("Started!");

  pinMode( ledPin, OUTPUT );
  digitalWrite( ledPin, LOW );

  pinMode( powerPin, OUTPUT);
  digitalWrite(powerPin, LOW);    // brings ONKEY low to turn on the modem (aka pressing the ONKEY)
  delay(3000);
  digitalWrite(powerPin, HIGH);    // sets the pin HIGH again (restore 5V)
  delay(5000);

  // test LED pin
  digitalWrite ( ledPin, HIGH);
  delay(1000);
  digitalWrite( ledPin, LOW);
}

void loop()
{
    char SerialInByte;

    // Send anything we receive from the IDE to the modem
    if(Serial.available())
    {
       mySerial.print((unsigned char)Serial.read());
     }  
    else  if(mySerial.available())
    {
        char SerialInByte;
        SerialInByte = (unsigned char)mySerial.read();
        //SerialInByte = mySerial.read();

        // EN: Relay to Arduino IDE Monitor
        Serial.print( SerialInByte );

        // -------------------------------------------------------------------
        // EN: Program also listen to the GPRS shield message.
        // -------------------------------------------------------------------

        // EN: If the message ends with <CR> then process the message
        if( SerialInByte == 13 ){
          // EN: Store the char into the message buffer
          ProcessGprsMsg();
         }
         if( SerialInByte == 10 ){
            // EN: Skip Line feed
         }
         else {
           // EN: store the current character in the message string buffer
           msg += String(SerialInByte);
         }
     }  
}

// EN: Make action based on the content of the SMS.
//     Notice than SMS content is the result of the processing of several GPRS shield messages.
void ProcessSms( String sms ){
  sms.toLowerCase();
  Serial.print("ProcessSms for [" );
  Serial.print( sms );
  Serial.println("]" );

  if( sms.indexOf("on") >= 0 ){
    digitalWrite( ledPin, HIGH );
    Serial.println("LED IS ON" );
    return;
  }
  if( sms.indexOf("off") >= 0 ){
    digitalWrite( ledPin, LOW );
    Serial.println("LED IS OFF" );
    return;
  } else {
    mySerial.print("AT+CMGF=1\
");    //Because we want to send the SMS in text mode
    delay(1000);
    mySerial.print("AT+CMGS="");
    mySerial.print(snFull);
    mySerial.print(""\
");
    delay(1000);
    mySerial.print("Unknown Command:");
    mySerial.print(sms);
    mySerial.print("\
");
    delay(1000);
    mySerial.write(0x1A);  //Equivalent to sending Ctrl+Z    
    return;
  }
}
// EN: Request Text Mode for SMS messaging
void GprsTextModeSMS(){
  mySerial.println("AT+CMGF=1" );
}

void GprsReadSmsStore( String SmsStorePos ){
  // Serial.print("GprsReadSmsStore for storePos" );
  // Serial.println( SmsStorePos );
  mySerial.print("AT+CMGR=" );
  mySerial.println( SmsStorePos );
}

// EN: Clear the GPRS shield message buffer
void ClearGprsMsg(){
  msg ="";
}

// EN: interpret the GPRS shield message and act appropiately
void ProcessGprsMsg() {
  Serial.println("");
  Serial.print("GPRS Message: [" );
  Serial.print( msg );
  Serial.println("]" );

  if( msg.indexOf("Call Ready" ) >= 0 ){
     Serial.println("*** GPRS Shield registered on Mobile Network ***" );
     GprsTextModeSMS();
  }

  // EN: unsolicited message received when getting a SMS message
  if( msg.indexOf("+CMTI" ) >= 0 ){
     Serial.println("*** SMS Received ***" );
     // EN: Look for the coma in the full message (+CMTI:"SM",6)
     //     In the sample, the SMS is stored at position 6
     int iPos = msg.indexOf("," );
     SmsStorePos = msg.substring( iPos+1 );
     Serial.print("SMS stored at" );
     Serial.println( SmsStorePos );

     // EN: Ask to read the SMS store
     GprsReadSmsStore( SmsStorePos );
  }

  // EN: SMS store read via UART (result of GprsReadSmsStore request)  
  if( msg.indexOf("+CMGR:" ) >= 0 ){
    // get number of sender
    int snPos = msg.indexOf("+1");
    Serial.print("SMS From:");
    snTmp = msg.substring(snPos+1);
    snFull ="";
    for (int i = 0; i < 11; i++){
      snFull += snTmp[i];    
    }
    Serial.println(snFull);

    // EN: Next message will contains the BODY of SMS
    SmsContentFlag = 1;
    // EN: Following lines are essentiel to not clear the flag!
    ClearGprsMsg();
    return;
  }

  // EN: +CMGR message just before indicate that the following GRPS Shield message
  //     (this message) will contains the SMS body
  if( SmsContentFlag == 1 ){
    Serial.println("*** SMS MESSAGE CONTENT ***" );
    Serial.println( msg );
    Serial.println("*** END OF SMS MESSAGE ***" );
    ProcessSms( msg );
    delSMS();
  }

  ClearGprsMsg();
  // EN: Always clear the flag
  SmsContentFlag = 0;
}
void delSMS() {
  mySerial.print("AT+CMGD=");
  mySerial.println(SmsStorePos);
}

Serial.begin(9600);

Serial.begin(115200);

Serial.begin(9600);

Serial.begin(9600);