package store

import (
	"context"
	"database/sql"
	"fmt"
)

// WorkoutTypePace is a workout kind's user-declared target pace range and
// expected HR zone. Informational only -- never read by the classification
// rule engine. No history: fields are overwritten in place.
type WorkoutTypePace struct {
	WorkoutKindID   int64
	PaceMinSecPerKm *float64
	PaceMaxSecPerKm *float64
	ExpectedHRZone  *int
}

func scanWorkoutTypePace(row interface{ Scan(...any) error }) (WorkoutTypePace, error) {
	var p WorkoutTypePace
	err := row.Scan(&p.WorkoutKindID, &p.PaceMinSecPerKm, &p.PaceMaxSecPerKm, &p.ExpectedHRZone)
	return p, err
}

const workoutTypePaceColumns = `workout_kind_id, pace_min_sec_per_km, pace_max_sec_per_km, expected_hr_zone`

// GetWorkoutTypePace fetches the pace/zone row for one workout kind.
func (db *DB) GetWorkoutTypePace(ctx context.Context, workoutKindID int64) (WorkoutTypePace, error) {
	row := db.QueryRowContext(ctx, `SELECT `+workoutTypePaceColumns+` FROM workout_type_paces WHERE workout_kind_id = ?`, workoutKindID)
	p, err := scanWorkoutTypePace(row)
	if err == sql.ErrNoRows {
		return WorkoutTypePace{WorkoutKindID: workoutKindID}, nil
	}
	if err != nil {
		return WorkoutTypePace{}, fmt.Errorf("get workout type pace for kind %d: %w", workoutKindID, err)
	}
	return p, nil
}

// UpdateWorkoutTypePace overwrites the pace/zone row for one workout kind.
func (db *DB) UpdateWorkoutTypePace(ctx context.Context, p WorkoutTypePace) error {
	_, err := db.ExecContext(ctx, `
		UPDATE workout_type_paces SET pace_min_sec_per_km=?, pace_max_sec_per_km=?, expected_hr_zone=?
		WHERE workout_kind_id=?`,
		p.PaceMinSecPerKm, p.PaceMaxSecPerKm, p.ExpectedHRZone, p.WorkoutKindID)
	if err != nil {
		return fmt.Errorf("update workout type pace for kind %d: %w", p.WorkoutKindID, err)
	}
	return nil
}

// ListWorkoutTypePaces returns every workout kind's pace/zone row.
func (db *DB) ListWorkoutTypePaces(ctx context.Context) ([]WorkoutTypePace, error) {
	rows, err := db.QueryContext(ctx, `SELECT `+workoutTypePaceColumns+` FROM workout_type_paces ORDER BY workout_kind_id`)
	if err != nil {
		return nil, fmt.Errorf("list workout type paces: %w", err)
	}
	defer rows.Close()

	paces := []WorkoutTypePace{}
	for rows.Next() {
		p, err := scanWorkoutTypePace(rows)
		if err != nil {
			return nil, fmt.Errorf("scan workout type pace row: %w", err)
		}
		paces = append(paces, p)
	}
	return paces, rows.Err()
}