package store

import (
	"context"
	"fmt"
)

// Lap is one lap/split of an activity, from get_activity_splits, plus
// derived HR drift/recovery metrics computed from activity_samples.
//
// Deliberately NOT modeled here: StartTimeUTC, DistanceMeters, MaxHR,
// MaxSpeedMps, ElevationGainM, ElevationLossM (removed in the 2026-07
// dedup pass -- zero consumers anywhere, pure duplicates of RawJSON), plus
// DurationSeconds and AvgHR, which DO have a real frontend chart need but no
// backend one, so the API layer decodes them from RawJSON at response time
// instead of storing a redundant copy -- see decodeLapDisplayFields.
type Lap struct {
	ID                  int64
	ActivityID          int64
	LapIndex            int
	AvgSpeedMps         *float64
	IntensityType       string
	HRDriftBpmPerMin    *float64
	HRRecoveryBpmPerMin *float64
	// TargetPaceLowMps/High and TargetHRLowBpm/High hold the expected band
	// for this lap, resolved from the activity's structured Garmin workout
	// (see internal/sync's alignWorkoutTargets) when its steps line up 1:1
	// with the recorded laps. Nil when the activity has no structured
	// workout, the step counts don't match, or the step targets neither
	// pace nor heart rate.
	TargetPaceLowMps  *float64
	TargetPaceHighMps *float64
	TargetHRLowBpm    *float64
	TargetHRHighBpm   *float64
	RawJSON           string
}

// ReplaceLaps deletes any existing laps for activityID and inserts the given
// set, so re-syncing an activity's splits is idempotent.
func (db *DB) ReplaceLaps(ctx context.Context, activityID int64, laps []Lap) error {
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("begin replace laps tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.ExecContext(ctx, `DELETE FROM laps WHERE activity_id = ?`, activityID); err != nil {
		return fmt.Errorf("delete existing laps for activity %d: %w", activityID, err)
	}

	for _, l := range laps {
		_, err := tx.ExecContext(ctx, `
			INSERT INTO laps (
				activity_id, lap_index, avg_speed_mps,
				intensity_type, hr_drift_bpm_per_min, hr_recovery_bpm_per_min,
				target_pace_low_mps, target_pace_high_mps, target_hr_low_bpm, target_hr_high_bpm, raw_json
			) VALUES (?,?,?,?,?,?,?,?,?,?,?)`,
			activityID, l.LapIndex, l.AvgSpeedMps,
			l.IntensityType, l.HRDriftBpmPerMin, l.HRRecoveryBpmPerMin,
			l.TargetPaceLowMps, l.TargetPaceHighMps, l.TargetHRLowBpm, l.TargetHRHighBpm, l.RawJSON,
		)
		if err != nil {
			return fmt.Errorf("insert lap %d for activity %d: %w", l.LapIndex, activityID, err)
		}
	}
	return tx.Commit()
}

// LapsForActivity returns all laps for an activity, ordered by lap_index.
func (db *DB) LapsForActivity(ctx context.Context, activityID int64) ([]Lap, error) {
	rows, err := db.QueryContext(ctx, `
		SELECT id, activity_id, lap_index, avg_speed_mps,
			intensity_type, hr_drift_bpm_per_min, hr_recovery_bpm_per_min,
			target_pace_low_mps, target_pace_high_mps, target_hr_low_bpm, target_hr_high_bpm, raw_json
		FROM laps WHERE activity_id = ? ORDER BY lap_index`, activityID)
	if err != nil {
		return nil, fmt.Errorf("laps for activity %d: %w", activityID, err)
	}
	defer rows.Close()

	laps := []Lap{}
	for rows.Next() {
		var l Lap
		if err := rows.Scan(
			&l.ID, &l.ActivityID, &l.LapIndex, &l.AvgSpeedMps,
			&l.IntensityType, &l.HRDriftBpmPerMin, &l.HRRecoveryBpmPerMin,
			&l.TargetPaceLowMps, &l.TargetPaceHighMps, &l.TargetHRLowBpm, &l.TargetHRHighBpm, &l.RawJSON,
		); err != nil {
			return nil, fmt.Errorf("scan lap row: %w", err)
		}
		laps = append(laps, l)
	}
	return laps, rows.Err()
}