#include <TinyGPS++.h>

// Use ESP32's HardwareSerial (more reliable than SoftwareSerial)
static const int GPS_RX_PIN = 18;  // ESP32 receives on 18  (connect to GPS TX)
static const int GPS_TX_PIN = 5;   // ESP32 transmits on 5   (connect to GPS RX)
static const uint32_t GPS_BAUD   = 9600;

#define btn 35   // single button

int btnOld = 1;   // default HIGH (because of INPUT_PULLUP)
int btnNew;

bool gpsStreaming = false;  // flag to toggle ON/OFF

TinyGPSPlus gps;

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32 + GPS!");

  pinMode(btn, INPUT_PULLUP);

  // Map Serial1 to your chosen pins (RX=18, TX=5) at 9600 8N1
  Serial1.begin(GPS_BAUD, SERIAL_8N1, GPS_RX_PIN, GPS_TX_PIN);
  Serial.println("GPS UART (Serial1) started at 9600 baud");
}

void loop() {
  // Always feed GPS parser
  while (Serial1.available() > 0) {
    gps.encode(Serial1.read());
  }

  // Read button
  btnNew = digitalRead(btn);

  // Detect falling edge (button press)
  if (btnOld == HIGH && btnNew == LOW) {
    gpsStreaming = !gpsStreaming; // toggle flag
    Serial.println(gpsStreaming ? "📡 GPS Streaming STARTED" : "🛑 GPS Streaming STOPPED");
    delay(200); // debounce
  }

  btnOld = btnNew;

  // If streaming enabled, print GPS data
  if (gpsStreaming) {
    if (gps.location.isUpdated()) {
      Serial.print("LAT: ");
      Serial.println(gps.location.lat(), 6);
      Serial.print("LON: ");
      Serial.println(gps.location.lng(), 6);
    }

    static uint32_t last = 0;
    if (millis() - last > 1000) {
      last = millis();
      Serial.print("Sats: ");
      Serial.print(gps.satellites.value());
      Serial.print("  HDOP: ");
      Serial.print(gps.hdop.hdop());
      Serial.print("  Valid: ");
      Serial.println(gps.location.isValid() ? "yes" : "no");
    }
  }
}