feat: extend equipment and workout models with service tracking

internal/activity/fit_parser.go

@@ -0,0 +1,94 @@
+package activity
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/muktihari/fit/decoder"
+	"github.com/muktihari/fit/profile/basetype"
+	"github.com/muktihari/fit/profile/mesgdef"
+	"github.com/muktihari/fit/profile/typedef"
+)
+
+// ParseFIT decodes a FIT activity file and extracts session-level metrics.
+func ParseFIT(data []byte) (*ParsedActivity, error) {
+	dec := decoder.New(bytes.NewReader(data))
+
+	if !dec.Next() {
+		return nil, fmt.Errorf("empty or invalid FIT file")
+	}
+
+	fit, err := dec.Decode()
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode FIT file: %w", err)
+	}
+
+	result := &ParsedActivity{}
+	foundSession := false
+
+	for i := range fit.Messages {
+		if fit.Messages[i].Num != typedef.MesgNumSession {
+			continue
+		}
+
+		foundSession = true
+		session := mesgdef.NewSession(&fit.Messages[i])
+
+		// total_elapsed_time: FIT stores as uint32 with scale 1000 (ms -> seconds)
+		if session.TotalElapsedTime != basetype.Uint32Invalid {
+			result.Duration = int(session.TotalElapsedTime / 1000)
+		}
+
+		// total_distance: FIT stores as uint32 with scale 100 (centimeters -> meters)
+		// Convert to km for our model
+		if session.TotalDistance != basetype.Uint32Invalid {
+			result.Distance = float64(session.TotalDistance) / 100.0 / 1000.0
+		}
+
+		// Power (no scale)
+		if session.AvgPower != basetype.Uint16Invalid {
+			result.AvgPower = int(session.AvgPower)
+		}
+		if session.MaxPower != basetype.Uint16Invalid {
+			result.MaxPower = int(session.MaxPower)
+		}
+
+		// Heart rate (no scale)
+		if session.AvgHeartRate != basetype.Uint8Invalid {
+			result.AvgHR = int(session.AvgHeartRate)
+		}
+		if session.MaxHeartRate != basetype.Uint8Invalid {
+			result.MaxHR = int(session.MaxHeartRate)
+		}
+
+		// Calories (no scale)
+		if session.TotalCalories != basetype.Uint16Invalid {
+			result.CaloriesBurned = int(session.TotalCalories)
+		}
+
+		// Elevation gain (no scale, meters)
+		if session.TotalAscent != basetype.Uint16Invalid {
+			result.ElevGain = int(session.TotalAscent)
+		}
+
+		// Cadence (no scale)
+		if session.AvgCadence != basetype.Uint8Invalid {
+			result.AvgCadence = int(session.AvgCadence)
+		}
+
+		// Start time
+		if session.StartTime.IsZero() {
+			result.StartTime = session.Timestamp
+		} else {
+			result.StartTime = session.StartTime
+		}
+
+		break // use first session
+	}
+
+	if !foundSession {
+		return nil, fmt.Errorf("no session data found in FIT file")
+	}
+
+	return result, nil
+}