#include <TinyGPSPlus.h>
#include "gps.h"
#include "sensor_node_config.h"
namespace { TinyGPSPlus parser; }

namespace {
uint32_t activeBaud = GPS_FALLBACK_BAUD;

bool baudHasValidNmea(HardwareSerial& serial, uint32_t baud) {
    TinyGPSPlus probe;
    serial.end();
    serial.begin(baud, SERIAL_8N1, GPS_RX_PIN, GPS_TX_PIN);
    unsigned long started = millis();
    while (millis() - started < GPS_BAUD_DETECT_MS) {
        while (serial.available()) probe.encode(serial.read());
        if (probe.passedChecksum() > 0) return true;
        delay(1);
    }
    return false;
}
}

void initGps(HardwareSerial& serial) {
    const uint32_t candidates[] = {9600, 38400, 115200, 4800};
    Serial.println("Detecting GPS UART baud...");
    for (uint32_t baud : candidates) {
        Serial.print("Trying GPS baud ");
        Serial.println(baud);
        if (!baudHasValidNmea(serial, baud)) continue;
        activeBaud = baud;
        Serial.print("Valid GPS NMEA detected at ");
        Serial.println(activeBaud);
        return;
    }

    activeBaud = GPS_FALLBACK_BAUD;
    serial.end();
    serial.begin(activeBaud, SERIAL_8N1, GPS_RX_PIN, GPS_TX_PIN);
    Serial.println("No valid GPS NMEA detected; falling back to 9600 baud");
}

void updateGps(HardwareSerial& serial, GpsState& s) {
    while (serial.available()) { s.lastByteMs = millis(); parser.encode(serial.read()); }
    s.charactersProcessed = parser.charsProcessed();
    s.sentencesPassed = parser.passedChecksum();
    s.sentencesFailed = parser.failedChecksum();
    s.baud = activeBaud;
    s.online = s.lastByteMs && millis() - s.lastByteMs <= SENSOR_STALE_MS;
    s.fix = parser.location.isValid() && parser.location.age() <= SENSOR_STALE_MS;
    s.satellites = parser.satellites.isValid() ? parser.satellites.value() : 0;
    if (parser.location.isValid()) { s.latitude = parser.location.lat(); s.longitude = parser.location.lng(); }
    if (parser.altitude.isValid()) s.altitudeMeters = parser.altitude.meters();
    if (parser.speed.isValid()) s.speedKph = parser.speed.kmph();
    if (parser.course.isValid()) s.courseDegrees = parser.course.deg();
    if (parser.date.isValid()) { s.year = parser.date.year(); s.month = parser.date.month(); s.day = parser.date.day(); }
    if (parser.time.isValid()) { s.hour = parser.time.hour(); s.minute = parser.time.minute(); s.second = parser.time.second(); }
}