#include <TinyGPS++.h>

#define GPS_BAUDRATE 9600
#define RXD2 16
#define TXD2 17

TinyGPSPlus gps;

void initSerial();
void readGPSData();
void printLocation();
void printSpeed();
void printDateTime();
void checkNoGPSData();

void setup() {
  initSerial();
}

void loop() {
  readGPSData();
  checkNoGPSData();
}

// ------------------ Initialization ------------------

void initSerial() {
  Serial.begin(9600);
  Serial2.begin(GPS_BAUDRATE, SERIAL_8N1, RXD2, TXD2);
  Serial.println(F("NEO6M GPS Module Simulation on ESP32"));
}

// ------------------ GPS Reading ------------------

void readGPSData() {
  while (Serial2.available() > 0) {
    if (gps.encode(Serial2.read())) {
      printLocation();
      printSpeed();
      printDateTime();
      Serial.println();
    }
  }
}

// ------------------ Output Functions ------------------

void printLocation() {
  Serial.print(F("Location:\t("));

  if (gps.location.isValid()) {
    Serial.print(F("Latitude: "));
    Serial.print(gps.location.lat(), 6);
    Serial.print(F(", Longitude: "));
    Serial.print(gps.location.lng(), 6);
    Serial.print(F(", Altitude: "));

    if (gps.altitude.isValid()) {
      Serial.print(gps.altitude.meters());
    } else {
      Serial.print(F("INVALID"));
    }
  } else {
    Serial.print(F("INVALID"));
  }

  Serial.println(F(")"));
}

void printSpeed() {
  Serial.print(F("Speed:\t\t"));

  if (gps.speed.isValid()) {
    Serial.print(gps.speed.kmph());
    Serial.println(F(" km/h"));
  } else {
    Serial.println(F("INVALID"));
  }
}

void printDateTime() {
  Serial.print(F("GPS Date&Time:\t"));

  if (gps.date.isValid() && gps.time.isValid()) {
    Serial.print(gps.date.year());
    Serial.print(F("-"));
    Serial.print(gps.date.month());
    Serial.print(F("-"));
    Serial.print(gps.date.day());
    Serial.print(F(" "));
    Serial.print(gps.time.hour());
    Serial.print(F(":"));
    Serial.print(gps.time.minute());
    Serial.print(F(":"));
    Serial.println(gps.time.second());
  } else {
    Serial.println(F("INVALID"));
  }
}

// ------------------ Error Checking ------------------

void checkNoGPSData() {
  if (millis() > 5000 && gps.charsProcessed() < 10) {
    Serial.println(F("No GPS data received: check wiring"));
  }
}