//Include libraries
#include <ArduinoJson.h>

//Defines the RX and TX pins for the cellular modem
#define RXD2 16
#define TXD2 17

#define CITY = “Warszawa”
#define COUNTRY_CODE = “PL”

#define CITY = “City of London”
#define COUNTRY_CODE = “GB” 

//Define the API key and URL for OpenWeatherMap
#define API_KEY "PLACE FOR API KEY"

#define URL "http://api.openweathermap.org/data/2.5/weather?q=" CITY "," COUNTRY_CODE "&units=metric&appid=" API_KEY

Stała wartość adresu URL - dane o mieście oraz kraju - wskazanie jednostek - zawarcie klucza API

String TEST_PHONE_NUMBER = “+442076350000”

String TEST_PHONE_NUMBER = “+48505505505”

String SIM_CARD_PIN_NUMBER = “1234”

String APN_ADDRESS = “internet”

String APN_ADDRESS = “internet.telekom”

//Function to turn on a modem
void setupModem()
{
  //Read any available data from the modem's serial interface
  download_data = Serial2.readString(); //Reading data from modem UART

  //Check if the modem is already on or not
  Serial2.println("AT");  //Send command to check if modem is on
  download_data = Serial2.readString(); //Reading data from modem UART
  if(download_data.indexOf("OK") > -1)  //Waiting for "OK" response from modem
  {
    // Modem is already on
    Serial.println(); //Print blank line in Serial Monitor
    Serial.println(download_data); //Print data from modem UART
    Serial.println(); //Print blank line in Serial Monitor
    Serial.println("Set modem startup:"); //Printing information in Serial Monitor
    Serial.println("Modem is aleady on"); //Printing information in Serial Monitor
    Serial.println(); //Print blank line in Serial Monitor
    download_data = ""; //Clearing variable
  } 

  else 
  {
    //Modem was off, turn it on
    Serial.println(); //Print blank line in Serial Monitor
    Serial.println(download_data); //Print data from modem UART
    Serial.println("Set modem startup:"); //Printing information in Serial Monitor
    Serial.println("The modem has been switched on"); //Printing information in Serial Monitor
    Serial.println(); //Print blank line in Serial Monitor
    digitalWrite(MODEM_PWRKEY, HIGH); //Turning ON modem by set power on PWR_KEY pin through 1000 ms
    delay(1000); //1000 ms pause
    digitalWrite(MODEM_PWRKEY, LOW); //Turning OFF PWR_KEY pin
    Serial2.println("ATE1"); //Set echo text mode on modem
    download_data = ""; //Clearing variable
    download_data = Serial2.readString(); //Reading data from modem UART
    int initial_counter = 0; //Blank initial counter
    delay(1000); //1000 ms pause

    while(download_data.indexOf("Call Ready") == -1) //Waiting for "Call Ready" response from modem
    {
      Serial.println("Waiting for modem init"); //Printing information in Serial Monitor
      delay(500); //500 ms pause
      download_data = Serial2.readString(); //Reading data from modem UART
      Serial.println(download_data); //Print data from modem UART
      initial_counter++; //Increase the counter value by 1
      if(initial_counter > 10) //Trying to turn up modem again
      {
        digitalWrite(MODEM_PWRKEY, HIGH); //Turning ON modem by set power on PWR_KEY pin through 1000 ms
        delay(1000); //1000 ms pause
        digitalWrite(MODEM_PWRKEY, LOW); //Turning OFF PWR_KEY pin
        initial_counter = 0; //Blank initial counter
      }
    }
  }
}

//Function to configuration the modem
void configurationModem() 
{
  Serial2.println("ATV1"); //Set verbose mode on
  Serial2.println("AT+CMEE=2"); //Enable extended error reporting
  Serial2.println("AT+IPR=115200"); //Set baud rate to 115200
  Serial2.println("ATI"); //Get modem info
  if(SIM_CARD_PIN_NUMBER != "") 
  {   //If SIM card requires a PIN, enter it
    Serial2.println((String) "AT+CPIN=" + SIM_CARD_PIN_NUMBER);
  }
  Serial2.println("AT+GSN"); //Get IMEI number
  Serial2.println("AT+CIMI"); //Get IMSI number
  Serial2.println("AT+QCCID"); //Get ICCID number
  Serial2.println((String) "AT+QICSGP=1,\"" + APN_ADDRESS + "\""); //Set APN address
  delay(100); //100 ms pause
  download_data = Serial2.readString(); //Reading data from modem UART
  Serial.println(); //Print blank line in Serial Monitor
  Serial.println(download_data); //Print data from modem UART
  Serial.println(); //Print blank line in Serial Monitor
  Serial.println("MODEM HAS BEEN CONFIGURED"); //Printing information in Serial Monitor
  download_data = ""; //Clearing variable
}

//Function to check status of cellular connection
void networkCheck() 
{
  download_data = ""; //Clearing variable
  Serial.println("Network test"); //Printing information in Serial Monitor
  int connecting_count = 0; //Blank initial counter
  while (download_data == "") //While download_data variable is empty
  {
    Serial2.println("AT+CREG?");  //Send command to get network registration status
    download_data = Serial2.readString(); //Reading data from modem UART
    if(download_data.indexOf("+CREG: 0,1") != -1) //Check if device is registered on home network
    {
      Serial.println("Network registered - home"); //Printing information in Serial Monitor
      Serial.println(download_data); //Print data from modem UART
      delay(50); //50 ms pause
      break; //Quit from while loop
    } 
    else if(download_data.indexOf("+CREG: 0,5") != -1) //Check if device is registered on roaming network
    {
      Serial.println("Network registered - roaming"); //Printing information in Serial Monitor
      Serial.println(download_data); //Print data from modem UART
      delay(50); //50 ms pause
      break; //Quit from while loop
    } 
    else if(download_data.indexOf("+CME ERROR: SIM failure") != -1) //Check if there is a SIM failure error
    {
      Serial.println("SIM card error"); //Printing information in Serial Monitor
      Serial.println(download_data); //Print data from modem UART
      download_data = Serial2.readString(); //Reading data from modem UART
      download_data = ""; //Clearing variable
      delay(50); //50 ms pause
    } 
    else if(download_data.indexOf("+CME ERROR: 13") != -1) //Check if there is a SIM failure error in CME numeric form
    {
      Serial.println("SIM card error"); //Printing information in Serial Monitor
      Serial.println(download_data); //Print data from modem UART
      download_data = Serial2.readString(); //Reading data from modem UART
      download_data = ""; //Clearing variable
      delay(50); //50 ms pause
    }
    else
    {
      Serial.println("Connecting to network"); //Printing information in Serial Monitor
      Serial.println(download_data); //Print data from modem UART
      download_data = ""; //Clearing variable
      delay(1000); //1000 ms pause
      connecting_count++; //Increase the counter value by 1
    }
    if(connecting_count > 75)
    {
      setupModem(); //Check that the modem is working properly
      configurationModem(); //Make configuration again
      Serial.println("Some network connectivity issues... trying to connect again"); //Printing information in Serial Monitor
      delay(5000); //5000 ms pause
      connecting_count = 0; //Blank initial counter
    }
  }
}

//Function to send an SMS message
void sendSMS(String phone_number, String message) 
{
  Serial2.println("AT+CMGF=1"); //Setup type of text message
  Serial2.println("AT+CSCS=\"GSM\""); //Select character set
  Serial2.println((String) "AT+CMGS=\"" + phone_number + "\""); //Send SMS in text mode
  Serial2.println(message); //Printing message in Serial Monitor
  Serial2.write(26); //Send CTRL+Z in Ascii
  Serial2.println(); //Print blank line in Serial Monitor
  //Wait for a response from the modem
  delay(2000); //2000 ms pause
    String response = Serial2.readString(); //Reading data from modem UART
    Serial.println(response); //Printing information in Serial Monitor
    if(response.indexOf("+CMGS:") != -1) //Waiting for "+CMGS:" response from modem
    {
      Serial.println("SMS message sent successfully!"); //Printing information in Serial Monitor
      Serial.println("Modem sent SMS message to:"); //Printing information in Serial Monitor
      Serial.println(TEST_PHONE_NUMBER); //Printing phone number in Serial Monitor
      Serial.println("SMS content:"); //Printing information in Serial Monitor
      Serial.println(message); //Printing message in Serial Monitor
      Serial.println(); //Print blank line in Serial Monitor
    }
}

void setup() 
{
  Serial.begin(115200); //Start main UART interface
  Serial.setTimeout(100); //Set timeout for main UART interface
  Serial2.begin(115200, SERIAL_8N1, RXD2, TXD2); //Configure and start Serial2 UART interface
  pinMode(MODEM_PWRKEY, OUTPUT); //Set MODEM_PWRKEY as output
  Serial2.setTimeout(100); //Set timeout for Serial2 UART interface
  setupModem(); //Run GSM modem
  configurationModem(); //Configuration GSM modem
  networkCheck();  //Check status of cellular connection
}

void loop() 
{
  bool connection_established = false; //Flag to track if modem connection was established
  bool http_request_successful = false; //Flag to track if HTTP request was successful
  int retry_count = 0; //Counter to keep track of number of retries

  download_data = Serial2.readString(); //Reading data from modem UART
  download_data = ""; //Clearing variable

  while (!connection_established && retry_count < MAX_RETRY_COUNT) //if connection_estabilished is false and retry count is less than MAX_RETRY_COUNT
  {
    Serial2.println("AT+QIFGCNT=0"); //Set MUXIP function to GPRS
    delay(50); //50 ms pause
    Serial2.println((String) "AT+QICSGP=1,\"" + APN_ADDRESS + "\""); //Set APN for your cellular provider
    delay(50); //50 ms pause
    Serial2.println("AT+QIREGAPP"); //Start TCPIP task
    delay(1000); //1000 ms pause
    download_data = Serial2.readString(); //Reading data from modem UART
    if(download_data.indexOf("OK") != -1) //Waiting for "OK" response from modem
    {
      Serial2.println("AT+QIACT"); //Bring up connection with GPRS
      delay(1000); //1000 ms pause
      download_data = Serial2.readString(); //Reading data from modem UART
      Serial.println(download_data); //Print data from modem UART
      if(download_data.indexOf("OK") != -1) //Waiting for "OK" response from modem
      {
        Serial.println("Modem is connected to cellular network."); //Printing information in Serial Monitor
        connection_established = true; //Changing variable value to exit from while loop
      }
      else
      {
        Serial.println("Modem not connected to cellular network."); //Printing information in Serial Monitor
        Serial2.println("AT+QIDEACT"); //Deactivate current GPRS context
        delay(5000); //5000 ms pause
      }
    }

    if(!connection_established) //if connection_estabilished variable is false
    {
      retry_count++; //Increase the counter value by 1
      Serial.println("Retrying connection establishment..."); //Printing information in Serial Monitor
      delay(1000); //1000 ms pause
    }
  }

  if(connection_established) //if connection_estabilished variable is true
  {
    int URL_length = strlen(url_cstr); //Get the length of the URL
    Serial2.println("AT+QHTTPCFG=\"requestheader\",0"); //Disable request header
    delay(50); //50 ms pause
    Serial2.println("AT+QHTTPURL=" + String(strlen(url_cstr)) + ",80"); //Send the HTTP URL through AT command and Serial2 interface
    delay(1000); //1000 ms pause
    Serial2.println(url_cstr); //Send the URL string through Serial2 interface
    delay(1000); //1000 ms pause
    Serial2.println("AT+QHTTPGET=80"); //Send an HTTP GET request
    delay(500); //500 ms pause
    download_data = Serial2.readString(); //Reading data from modem UART

    retry_count = 0; //Blank initial counter
    while(!http_request_successful && retry_count < MAX_RETRY_COUNT) //if http_request_successful is false and retry count is less than MAX_RETRY_COUNT
    {
      download_data = ""; //Clearing variable
      while(download_data.indexOf("CONNECT") == -1) //Waiting for "CONNECT" response from modem
      {
        Serial2.println("AT+QHTTPREAD=80"); //Reading data from server
        download_data = Serial2.readString(); //Reading data from modem UART
        Serial.println(download_data); //Print data from modem UART
        delay(500); //500 ms pause
      }  

download_data.replace("OK", ""); //Replacing unnecessary data from modem response
      download_data.replace("AT+QHTTPGET=80", "");//Replacing unnecessary data from modem response
      download_data.replace("AT+QHTTPREAD=80", "");//Replacing unnecessary data from modem response
      download_data.replace("CONNECT", ""); //Replacing unnecessary data from modem response
      download_data.trim(); //Whitespaces delete
      if(download_data.indexOf("ERROR") == -1)  //Waiting for response without "ERROR" from modem
      {
        http_request_successful = true; //Changing variable value to check HTTP request status
        Serial.println(download_data); //Print data from modem UART

        //Parse the JSON response
        StaticJsonDocument<1000> doc; //Managing memory for JSON object
        DeserializationError error = deserializeJson(doc, download_data); // Deserialization of JSON data

        if(error) //If is error with JSON object deserialization
        {
          Serial.println("JSON parsing failed!"); //Printing information in Serial Monitor
          Serial.println(error.c_str());  //Display type of the error
          return; //Return error information
        } 
        else 
        {
          Serial.println("JSON parsing successful!"); //Printing information in Serial Monitor
          float temperature = doc["main"]["temp"]; //Parsing JSON temperature data
          float pressure = doc["main"]["pressure"]; //Parsing JSON pressure data
          float humidity = doc["main"]["humidity"]; //Parsing JSON humidity data
          float wind_speed = doc["wind"]["speed"]; //Parsing JSON wind speed data
          Serial.print("Temperature: "); //Printing information in Serial Monitor
          Serial.println(temperature); //Printing temperature in Serial Monitor
          Serial.print("Pressure: "); //Printing information in Serial Monitor
          Serial.println(pressure); //Printing pressure in Serial Monitor
          Serial.print("Humidity: "); //Printing information in Serial Monitor
          Serial.println(humidity); //Printing humidity in Serial Monitor
          Serial.print("Wind speed: "); //Printing information in Serial Monitor
          Serial.println(wind_speed); //Printing wind speed in Serial Monitor

//Send an SMS message
          if (temperature >= -1) //if temperature is less than -1 C
          {
            unsigned long current_time = millis(); //create variable for millis time function
            if ((current_time - last_message_sent_time >= TWELVE_HOURS) || !FIRST_MESSAGE_SENT) {
              //Parsing message data
              String message = "Alert! You may expecting temperature of " + String(temperature) + " degrees with humidity of: " + String(humidity) + "%" + ", wind speed of: " + String(wind_speed) + "km/h and pressure " + String(pressure) + "Pa";
              sendSMS(TEST_PHONE_NUMBER, message);     //Call the SMS function and pass parameters 
              last_message_sent_time = current_time;  //Update the time of the last message sent
              FIRST_MESSAGE_SENT = true; //Set FIRST_MESSAGE_SENT variable as true
            } 
            else 
            {
              Serial.print("SMS sending is currently restricted due to a previous message sent within the last 12 hours."); //Printing information in Serial Monitor
            }
          }

(current_time - last_message_sent_time >= TWELVE_HOURS) || !FIRST_MESSAGE_SENT