/*
  Modified: Receive Calls with TTGO ESP32 SIM800L
*/

#include "Adafruit_FONA.h"

#define SIM800L_RX     27
#define SIM800L_TX     26
#define SIM800L_PWRKEY 4
#define SIM800L_RST    5
#define SIM800L_POWER  23

HardwareSerial *sim800lSerial = &Serial1;
Adafruit_FONA sim800l = Adafruit_FONA(SIM800L_PWRKEY);

#define LED_BLUE  13
#define RELAY 14

void setup() {
  pinMode(LED_BLUE, OUTPUT);
  pinMode(RELAY, OUTPUT);
  pinMode(SIM800L_POWER, OUTPUT);

  digitalWrite(LED_BLUE, HIGH);
  digitalWrite(SIM800L_POWER, HIGH);

  Serial.begin(115200);
  Serial.println(F("ESP32 with GSM SIM800L"));
  Serial.println(F("Initializing....(May take more than 10 seconds)"));
  
  delay(10000);

  sim800lSerial->begin(4800, SERIAL_8N1, SIM800L_TX, SIM800L_RX);
  if (!sim800l.begin(*sim800lSerial)) {
    Serial.println(F("Couldn't find GSM SIM800L"));
    while (1);
  }
  Serial.println(F("GSM SIM800L is OK"));

  char imei[16] = {0};
  if (sim800l.getIMEI(imei)) {
    Serial.print("SIM card IMEI: "); Serial.println(imei);
  }

  // Enable call notification
  sim800lSerial->print("AT+CLCCr");
  Serial.println("Call notification enabled");
}

void loop() {
  if (sim800l.available()) {
    String response = "";
    while (sim800l.available()) {
      response += (char)sim800l.read();
    }
    Serial.println(response);

    // Check for incoming call
    if (response.indexOf("RING") >= 0) {
      Serial.println("Incoming call detected!");
    }
  }
}