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package ride
import (
"bytes"
"encoding/binary"
"errors"
"io"
"math"
"time"
"github.com/jftuga/geodist"
"github.com/martinlehoux/kagamigo/kcore"
"github.com/tormoder/fit"
)
// FITRideParser parses FIT files into Ride values. It is the FIT counterpart
// to GPXRideParser and keeps the same invariants.
type FITRideParser struct{}
func (p FITRideParser) Parse(reader io.Reader) (Ride, error) {
data, err := io.ReadAll(reader)
if err != nil {
return Ride{}, err
}
file, err := fit.Decode(bytes.NewReader(data))
if err != nil {
return Ride{}, err
}
activity, err := file.Activity()
if err != nil {
return Ride{}, err
}
if len(activity.Records) == 0 {
return Ride{}, ErrNoTrackPoints
}
// Collect points discarding invalid positions — FIT encodes missing lat/lon
// as 0x7FFFFFFF (Invalid). We also require altitude.
records := activity.Records
distances := make([]float64, 0, len(records))
elevations := make([]float64, 0, len(records))
coords := make([]geodist.Coord, 0, len(records))
timestamps := make([]time.Time, 0, len(records))
heartRates := make([]float64, 0, len(records))
cadences := make([]float64, 0, len(records))
powers := make([]float64, 0, len(records))
heartRateComplete := true
cadenceComplete := true
powerComplete := true
distance := 0.0
var previous *geodist.Coord
for _, rec := range records {
if rec.PositionLat.Invalid() || rec.PositionLong.Invalid() {
continue
}
if rec.Altitude == 0xFFFF {
return Ride{}, errors.New("points without elevation")
}
altitude := rec.GetAltitudeScaled()
if math.IsNaN(altitude) {
return Ride{}, errors.New("points without elevation")
}
coord := geodist.Coord{Lat: rec.PositionLat.Degrees(), Lon: rec.PositionLong.Degrees()}
if previous != nil {
_, km := geodist.HaversineDistance(*previous, coord)
d := km * 1000
if d == 0 {
continue
}
distance += d
}
previous = &coord
distances = append(distances, distance)
elevations = append(elevations, altitude)
coords = append(coords, coord)
// FIT timestamps are absolute; if missing they are zero time.
ts := rec.Timestamp
if ts.IsZero() {
ts = file.FileId.TimeCreated
}
timestamps = append(timestamps, ts)
if rec.HeartRate == 0xFF {
heartRateComplete = false
heartRates = append(heartRates, 0)
} else {
heartRates = append(heartRates, float64(rec.HeartRate))
}
if rec.Cadence == 0xFF {
cadenceComplete = false
cadences = append(cadences, 0)
} else {
cadences = append(cadences, float64(rec.Cadence))
}
if rec.Power == 0xFFFF {
powerComplete = false
powers = append(powers, 0)
} else {
powers = append(powers, float64(rec.Power))
}
}
if len(distances) < 2 {
if len(distances) == 0 {
return Ride{}, ErrNoTrackPoints
}
return Ride{}, errors.New("zero distance")
}
var heartRatesColumn, cadencesColumn, powersColumn []float64
if heartRateComplete {
heartRatesColumn = heartRates
}
if cadenceComplete {
cadencesColumn = cadences
}
if powerComplete {
powersColumn = powers
}
return fromColumns(distances, elevations, coords, timestamps, heartRatesColumn, cadencesColumn, powersColumn), nil
}
// EncodeFIT writes the ride as a minimal FIT Activity file. It stores only the
// fields consumed by Ride (lat/lon, altitude, time, heart rate, cadence, power)
// as Record messages.
func EncodeFIT(ride Ride, w io.Writer) error {
kcore.Assert(ride.Len() > 0, "no points in ride")
h := fit.NewHeader(fit.V20, true)
file, err := fit.NewFile(fit.FileTypeActivity, h)
if err != nil {
return err
}
file.FileId.Manufacturer = fit.ManufacturerGarmin
file.FileId.Type = fit.FileTypeActivity
if len(ride.timestamps) > 0 {
file.FileId.TimeCreated = ride.timestamps[0]
} else {
file.FileId.TimeCreated = time.Now()
}
activity, err := file.Activity()
if err != nil {
return err
}
heartRates, hasHR := ride.HeartRates()
cadences, hasCad := ride.Cadences()
powers, hasPower := ride.Powers()
for i := 0; i < ride.Len(); i++ {
rec := fit.NewRecordMsg()
rec.Timestamp = ride.timestamps[i]
coord := ride.Coords[i]
rec.PositionLat = fit.NewLatitudeDegrees(coord.Lat)
rec.PositionLong = fit.NewLongitudeDegrees(coord.Lon)
// Altitude: scaled (value+500)*5, invalid 0xFFFF
elev := ride.Elevations[i]
scaled := min(max(int((elev+500)*5), 0), 0xFFFE)
rec.Altitude = uint16(scaled)
rec.EnhancedAltitude = 0xFFFFFFFF
if hasHR {
v := min(max(int(heartRates[i]), 0), 254)
rec.HeartRate = uint8(v)
} else {
rec.HeartRate = 0xFF
}
if hasCad {
v := min(max(int(cadences[i]), 0), 254)
rec.Cadence = uint8(v)
} else {
rec.Cadence = 0xFF
}
if hasPower {
v := min(max(int(powers[i]), 0), 65534)
rec.Power = uint16(v)
} else {
rec.Power = 0xFFFF
}
// Explicitly mark unused fields as invalid to keep encoding minimal.
rec.Distance = 0xFFFFFFFF
rec.Speed = 0xFFFF
rec.Grade = 0x7FFF
activity.Records = append(activity.Records, rec)
}
return fit.Encode(w, file, binary.LittleEndian)
}
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