Parse FIT Course files as rides

3 files changed, 102 insertions, 6 deletions

diff --git a/README.md b/README.md
index 69206ad..9562732 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ Climb profile by 100m step.
 
 **Analytics** - Plot speed vs difficulty, difficulty vs duration. Color points by type or season.
 
-**Preview** - Upload a raw GPX or FIT file at `/preview` to analyze it (climb detection, official-climb matching, mountain-pass crossings) without importing it; official climbs can be saved from a preview.
+**Preview** - Upload a raw GPX or FIT file (Activity or Course) at `/preview` to analyze it (climb detection, official-climb matching, mountain-pass crossings) without importing it; official climbs can be saved from a preview.
 
 **Elevation fix** - Hover the profile to see `#index · km · m`, run `go run . elevation analyse <id|all>` to flag unrealistic grades (>50% over <30m) and `go run . elevation fix <id> --from <index|km> --to <index|km> [--dry-run]` (or `--auto`) to linearly interpolate elevations between anchors, rewriting FIT+GPX (`.bak` kept) and recomputing Cotacol.
 
diff --git a/ride/fit.go b/ride/fit.go
index db9c0b6..61d0a7b 100644
--- a/ride/fit.go
+++ b/ride/fit.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"io"
 	"math"
 	"time"
@@ -13,8 +14,9 @@ import (
 	"github.com/tormoder/fit"
 )
 
-// FITRideParser parses FIT files into Ride values. It is the FIT counterpart
-// to GPXRideParser and keeps the same invariants.
+// FITRideParser parses FIT Activity and Course files into Ride values. Both
+// types store their track as Record messages. It is the FIT counterpart to
+// GPXRideParser and keeps the same invariants.
 type FITRideParser struct{}
 
 func (p FITRideParser) Parse(reader io.Reader) (Ride, error) {
@@ -26,17 +28,16 @@ func (p FITRideParser) Parse(reader io.Reader) (Ride, error) {
 	if err != nil {
 		return Ride{}, err
 	}
-	activity, err := file.Activity()
+	records, err := fitRecords(file)
 	if err != nil {
 		return Ride{}, err
 	}
-	if len(activity.Records) == 0 {
+	if len(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))
@@ -123,6 +124,27 @@ func (p FITRideParser) Parse(reader io.Reader) (Ride, error) {
 	return fromColumns(distances, elevations, coords, timestamps, heartRatesColumn, cadencesColumn, powersColumn), nil
 }
 
+// fitRecords returns the track points of an Activity or Course FIT file; both
+// store them as Record messages.
+func fitRecords(file *fit.File) ([]*fit.RecordMsg, error) {
+	switch file.Type() {
+	case fit.FileTypeActivity:
+		activity, err := file.Activity()
+		if err != nil {
+			return nil, err
+		}
+		return activity.Records, nil
+	case fit.FileTypeCourse:
+		course, err := file.Course()
+		if err != nil {
+			return nil, err
+		}
+		return course.Records, nil
+	default:
+		return nil, fmt.Errorf("fit file type is %v, not Activity or Course", file.Type())
+	}
+}
+
 // 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.
diff --git a/ride/fit_test.go b/ride/fit_test.go
new file mode 100644
index 0000000..9e9e0a3
--- /dev/null
+++ b/ride/fit_test.go
@@ -0,0 +1,74 @@
+package ride_test
+
+import (
+	"bytes"
+	"encoding/binary"
+	"testing"
+	"time"
+
+	"github.com/martinlehoux/biking_home/ride"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/tormoder/fit"
+)
+
+func encodeFIT(t *testing.T, fileType fit.FileType, records []*fit.RecordMsg) []byte {
+	t.Helper()
+	file, err := fit.NewFile(fileType, fit.NewHeader(fit.V20, true))
+	require.NoError(t, err)
+	file.FileId.Manufacturer = fit.ManufacturerGarmin
+	file.FileId.Type = fileType
+	file.FileId.TimeCreated = time.Date(2026, 8, 1, 7, 30, 0, 0, time.UTC)
+	switch fileType {
+	case fit.FileTypeCourse:
+		course, err := file.Course()
+		require.NoError(t, err)
+		course.Records = records
+	case fit.FileTypeActivity:
+		activity, err := file.Activity()
+		require.NoError(t, err)
+		activity.Records = records
+	}
+	var buf bytes.Buffer
+	require.NoError(t, fit.Encode(&buf, file, binary.LittleEndian))
+	return buf.Bytes()
+}
+
+func fitRecord(lat, lon, elevationM float64, ts time.Time) *fit.RecordMsg {
+	rec := fit.NewRecordMsg()
+	rec.Timestamp = ts
+	rec.PositionLat = fit.NewLatitudeDegrees(lat)
+	rec.PositionLong = fit.NewLongitudeDegrees(lon)
+	rec.Altitude = uint16((elevationM + 500) * 5)
+	rec.HeartRate = 0xFF
+	rec.Cadence = 0xFF
+	rec.Power = 0xFFFF
+	return rec
+}
+
+func TestFITRideParserParsesCourseFile(t *testing.T) {
+	base := time.Date(2026, 8, 1, 7, 30, 0, 0, time.UTC)
+	data := encodeFIT(t, fit.FileTypeCourse, []*fit.RecordMsg{
+		fitRecord(43.0, 5.0, 100, base),
+		fitRecord(43.0, 5.0, 101, base.Add(5*time.Second)), // stationary: skipped
+		fitRecord(43.001, 5.001, 200, base.Add(10*time.Second)),
+	})
+
+	parsed, err := (ride.FITRideParser{}).Parse(bytes.NewReader(data))
+	require.NoError(t, err)
+	require.Equal(t, 2, parsed.Len())
+	assert.Equal(t, 0.0, parsed.Distances[0])
+	assert.Greater(t, parsed.Distances[1], 0.0)
+	assert.Equal(t, []float64{100, 200}, parsed.Elevations)
+	assert.Equal(t, []time.Time{base, base.Add(10 * time.Second)}, parsed.Timestamps())
+	_, hasHR := parsed.HeartRates()
+	assert.False(t, hasHR, "course records carry no telemetry")
+}
+
+func TestFITRideParserRejectsFileWithoutTrack(t *testing.T) {
+	data := encodeFIT(t, fit.FileTypeSettings, nil)
+
+	_, err := (ride.FITRideParser{}).Parse(bytes.NewReader(data))
+	require.Error(t, err)
+	assert.Equal(t, "fit file type is Settings, not Activity or Course", err.Error())
+}