from ais_hub.core.stats import Stats
from ais_hub.parser.gps import GpsParser


def _withcs(body: str) -> str:
    cs = 0
    for ch in body.encode("ascii"):
        cs ^= ch
    return f"${body}*{cs:02X}"


def test_rmc_produces_lat_lon_sog_cog():
    p = GpsParser(stats=Stats())
    line = _withcs("GPRMC,123519,A,4807.038,N,01131.000,E,22.4,84.4,230394,3.1,W")
    fix = p.feed("gps_uart", line)
    assert fix is not None
    assert abs(fix.lat - (48 + 7.038 / 60)) < 1e-6
    assert abs(fix.lon - (11 + 31.0 / 60)) < 1e-6
    assert fix.sog == 22.4
    assert fix.cog == 84.4


def test_gga_supplies_fix_quality_and_hdop():
    p = GpsParser(stats=Stats())
    line = _withcs("GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,")
    fix = p.feed("gps_uart", line)
    assert fix is not None
    assert fix.fix_quality == 1
    assert fix.sats == 8
    assert fix.hdop == 0.9
    assert fix.alt == 545.4


def test_vtg_speed_from_kmh_when_knots_missing():
    p = GpsParser(stats=Stats())
    line = _withcs("GPVTG,054.7,T,034.4,M,,,010.0,K,A")
    fix = p.feed("gps_uart", line)
    assert fix is not None
    assert fix.cog == 54.7
    # 10 km/h ~ 5.3996 knots
    assert fix.sog is not None and abs(fix.sog - 5.3996) < 1e-3


def test_bad_checksum_rejected():
    p = GpsParser(stats=Stats())
    fix = p.feed("gps_uart", "$GPRMC,,,,,,,,,,,,*FF")
    assert fix is None