//see https://github.com/vshymanskyy/TinyGSM/blob/master/examples/HttpsClient/HttpsClient.ino
//see https://randomnerdtutorials.com/esp32-sim800l-publish-data-to-cloud/

#include <Arduino.h>
#include <ArduinoHttpClient.h>

// APN (example: internet.vodafone.pt) use https://wiki.apnchanger.org
const char apn[]      = "internet.tele2.ee"; 
const char gprsUser[] = ""; // GPRS User
const char gprsPass[] = ""; // GPRS Password

// SIM card PIN (leave empty, if not defined)
const char simPIN[]   = "0000";

// TTGO T-Call pins
#define MODEM_RST            5
#define MODEM_PWKEY          4
#define MODEM_POWER_ON       23
#define MODEM_TX             27
#define MODEM_RX             26
#define I2C_SDA              21
#define I2C_SCL              22

// Set serial for debug console (to Serial Monitor, default speed 115200)
#define SerialMon Serial
// Set serial for AT commands (to SIM800 module)
#define SerialAT Serial1

// Configure TinyGSM library
#define TINY_GSM_MODEM_SIM800      // Modem is SIM800
#define TINY_GSM_RX_BUFFER   1024  // Set RX buffer to 1Kb

#include <Wire.h>
#include <TinyGsmClient.h>

#ifdef DUMP_AT_COMMANDS
  #include <StreamDebugger.h>
  StreamDebugger debugger(SerialAT, SerialMon);
  TinyGsm modem(debugger);
#else
  TinyGsm modem(SerialAT);
#endif


// I2C for SIM800 (to keep it running when powered from battery)
TwoWire I2CPower = TwoWire(0);

// TinyGSM Client for Internet connection
TinyGsmClientSecure client(modem);

#define IP5306_ADDR          0x75
#define IP5306_REG_SYS_CTL0  0x00

bool setPowerBoostKeepOn(int en){
  I2CPower.beginTransmission(IP5306_ADDR);
  I2CPower.write(IP5306_REG_SYS_CTL0);
  if (en) {
    I2CPower.write(0x37); // Set bit1: 1 enable 0 disable boost keep on
  } else {
    I2CPower.write(0x35); // 0x37 is default reg value
  }
  return I2CPower.endTransmission() == 0;
}

  const char server[]   = "dev.intellisoft.ee";
  const char resource[] = "/";
  const int  port       = 443;

  HttpClient http(client, server, port);


void setup() {
  // Set serial monitor debugging window baud rate to 115200
  SerialMon.begin(115200);

  // Start I2C communication
  //I2CPower.begin(I2C_SDA, I2C_SCL, 400);
  //I2CPower.begin(I2C_SDA, I2C_SCL, 400000);

  // Keep power when running from battery
  //bool isOk = setPowerBoostKeepOn(1);
  //SerialMon.println(String("IP5306 KeepOn ") + (isOk ? "OK" : "FAIL"));

  // Set modem reset, enable, power pins
  pinMode(MODEM_PWKEY, OUTPUT);
  pinMode(MODEM_RST, OUTPUT);
  pinMode(MODEM_POWER_ON, OUTPUT);
  digitalWrite(MODEM_PWKEY, LOW);
  digitalWrite(MODEM_RST, HIGH);
  digitalWrite(MODEM_POWER_ON, HIGH);

  // Set GSM module baud rate and UART pins
  SerialAT.begin(115200, SERIAL_8N1, MODEM_RX, MODEM_TX);
  delay(3000);

  // Restart SIM800 module, it takes quite some time
  // To skip it, call init() instead of restart()
  SerialMon.println("Initializing modem...");
  modem.restart();
  // use modem.init() if you don't need the complete restart

  // Unlock your SIM card with a PIN if needed
  if (strlen(simPIN) && modem.getSimStatus() != 3 ) {
    modem.simUnlock(simPIN);
  }  
}

void loop() {
  SerialMon.print("Connecting to APN: ");
  SerialMon.print(apn);
  if (!modem.gprsConnect(apn, gprsUser, gprsPass)) {
    SerialMon.println(" fail");
  }
  else {
    SerialMon.println(" OK");
    SerialMon.println("Wait for network");
    if (!modem.waitForNetwork()) {
      SerialMon.println(" fail");
      delay(10000);
      return;
    }

    if (modem.isGprsConnected()) { SerialMon.println("GPRS connected"); }

      SerialMon.print(F("Performing HTTPS GET request... "));

    http.connectionKeepAlive();  // Currently, this is needed for HTTPS
    int err = http.get(resource);
    if (err != 0) {
      SerialMon.println(F("failed to connect"));
      delay(10000);
      return;
    }

    int status = http.responseStatusCode();
    SerialMon.print(F("Response status code: "));
    SerialMon.println(status);
    if (!status) {
      delay(10000);
      return;
    }

    SerialMon.println(F("Response Headers:"));
    while (http.headerAvailable()) {
      String headerName  = http.readHeaderName();
      String headerValue = http.readHeaderValue();
      SerialMon.println("    " + headerName + " : " + headerValue);
    }

    int length = http.contentLength();
    if (length >= 0) {
      SerialMon.print(F("Content length is: "));
      SerialMon.println(length);
    }
    if (http.isResponseChunked()) {
      SerialMon.println(F("The response is chunked"));
    }

    String body = http.responseBody();
    SerialMon.println(F("Response:"));
    SerialMon.println(body);

    SerialMon.print(F("Body length is: "));
    SerialMon.println(body.length());

    // Shutdown

    http.stop();
    SerialMon.println(F("Server disconnected"));



    modem.gprsDisconnect();
    SerialMon.println(F("GPRS disconnected"));
  }
}