package races

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/x0gp/server/internal/lobby"
)

// PodiumEntry is one row in the top-3 of a finished race. Ordered by
// Position (1..3). DriverID/Name are denormalised from the future
// drivers table; TotalTimeMs is the driver's total race time.
type PodiumEntry struct {
	Position    int    `json:"position" example:"1"`
	DriverID    string `json:"driver_id" example:"driver-alice"`
	Name        string `json:"name" example:"driver-alice"`
	TotalTimeMs int64  `json:"total_time_ms" example:"123456"`
	Nickname    string `json:"nickname" example:"driver-alice"`
	AvatarUrl   string `json:"avatar_url"`
	ClanID      string `json:"clan_id" example:"clan-bob"`
}

// DriverResult is the per-driver outcome of a race. Stored in
// race_drivers. DriverID + TotalTimeMs are required; BestLapMs is
// the driver's fastest lap; Position is 1..N when the driver
// finished, or NULL when DNF/DSQ. The aggregate podium and winner
// fields are derived from this row set on read.
type DriverResult struct {
	DriverID    string
	Name        string
	TotalTimeMs int64
	BestLapMs   int64
	Position    *int   // nil for DNF
	Nickname    string `json:"nickname" example:"driver-alice"`
	AvatarUrl   string `json:"avatar_url"`
	ClanID      string `json:"clan_id" example:"clan-bob"`
}

// FinishedRace is the on-disk shape of a completed race. Mirrors the
// lobby.RaceMeta plus aggregate outcome fields. Per-driver results
// (including the podium) live in race_drivers and are read into
// Results on demand.
type FinishedRace struct {
	ID           string
	Name         string
	TrackID      string
	MaxCars      int
	Laps         int
	TimeLimitS   int
	DriverIDs    []string
	Status       string // "finished" | "cancelled"
	CreatedMs    int64
	StartedMs    int64
	FinishedMs   int64
	DurationMs   int64
	TotalLaps    int
	TotalDrivers int

	// Results is the per-driver race_drivers data, hydrated on read.
	// Includes the winner and the podium.
	Results []DriverResult

	// Derived fields (computed in scanFinished from Results). The
	// public API exposes them so existing clients keep working.
	WinnerDriverID string
	WinnerName     string
	BestLapMs      int64
	Podium         []PodiumEntry
}

// RacePlan is a recurring or one-off scheduled race description.
type RacePlan struct {
	ID         string
	Name       string
	TrackID    string
	MaxCars    int
	Laps       int
	TimeLimitS int
	StartAtMs  int64
	IntervalS  int
	Count      int
	Enabled    bool
	CreatedMs  int64
	UpdatedMs  int64
	NextFireMs int64
	FiresDone  int
}

// QueueEntry is a single (driver, race) subscription.
type QueueEntry struct {
	DriverID   string
	RaceID     string
	PlanID     string
	EnqueuedMs int64
}

// PgStore is the Postgres-backed half of the races package.
type PgStore struct {
	pool *pgxpool.Pool
}

// NewPgStore wraps an open pgxpool.
func NewPgStore(pool *pgxpool.Pool) *PgStore {
	return &PgStore{pool: pool}
}

// Exec exposes a raw Exec for the seeder / maintenance scripts.
func (s *PgStore) Exec(ctx context.Context, sql string, args ...any) (int64, error) {
	tag, err := s.pool.Exec(ctx, sql, args...)
	if err != nil {
		return 0, err
	}
	return tag.RowsAffected(), nil
}

// ListTrackIDs returns all track ids from the tracks table. Used by
// the seeder to bind race_plans/finished_races to real catalog entries.
func (s *PgStore) ListTrackIDs(ctx context.Context) ([]string, error) {
	rows, err := s.pool.Query(ctx, `SELECT id FROM tracks ORDER BY id`)
	if err != nil {
		return nil, fmt.Errorf("list track ids: %w", err)
	}
	defer rows.Close()
	out := make([]string, 0)
	for rows.Next() {
		var id string
		if err := rows.Scan(&id); err != nil {
			return nil, err
		}
		out = append(out, id)
	}
	return out, rows.Err()
}

// ---------------------------------------------------------------------------
// Live race surface (status in lobby | countdown | racing).
//
// The unified `races` table holds both live and finished rows. Methods
// below are the write-side mirror for lobby.Service; reads flow through
// races.Service via ListRacesPaged (status filter) and ListUpcoming.
// ---------------------------------------------------------------------------

// UpsertLive mirrors a lobby.RaceMeta row. Only used for status in
// (lobby, countdown, racing). Status is enforced at the call site.
func (s *PgStore) UpsertLive(ctx context.Context, r lobby.RaceMeta) error {
	now := time.Now().UnixMilli()
	_, err := s.pool.Exec(ctx, `
		INSERT INTO races
		    (id, name, track_id, max_cars, laps, time_limit_s, status,
		     created_ms, started_ms, finished_ms, updated_ms)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, 0, $10)
		ON CONFLICT (id) DO UPDATE SET
		    name = EXCLUDED.name,
		    track_id = EXCLUDED.track_id,
		    max_cars = EXCLUDED.max_cars,
		    laps = EXCLUDED.laps,
		    time_limit_s = EXCLUDED.time_limit_s,
		    status = EXCLUDED.status,
		    started_ms = EXCLUDED.started_ms,
		    updated_ms = EXCLUDED.updated_ms`,
		r.ID, r.Name, r.TrackID, r.MaxCars, r.Laps, r.TimeLimitS, string(r.Status),
		r.CreatedMs, r.StartedMs, now)
	if err != nil {
		return fmt.Errorf("upsert live race %s: %w", r.ID, err)
	}
	return nil
}

// DeleteLive removes a live race row. The FK from race_drivers has
// CASCADE so the related drivers are also removed.
func (s *PgStore) DeleteLive(ctx context.Context, raceID string) error {
	_, err := s.pool.Exec(ctx, `DELETE FROM races WHERE id = $1 AND status IN ('lobby','countdown','racing')`, raceID)
	return err
}

// AddLiveDriver adds a driver to a live race (slot=position). Idempotent.
func (s *PgStore) AddLiveDriver(ctx context.Context, raceID, driverID string, slot int) error {
	now := time.Now().UnixMilli()
	_, err := s.pool.Exec(ctx, `
		INSERT INTO race_drivers (race_id, driver_id, slot, joined_ms)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (race_id, driver_id) DO UPDATE SET slot = EXCLUDED.slot`,
		raceID, driverID, slot, now)
	if err != nil {
		return fmt.Errorf("add live driver %s to %s: %w", driverID, raceID, err)
	}
	return nil
}

// RemoveLiveDriver removes a driver from a live race.
func (s *PgStore) RemoveLiveDriver(ctx context.Context, raceID, driverID string) error {
	_, err := s.pool.Exec(ctx,
		`DELETE FROM race_drivers WHERE race_id = $1 AND driver_id = $2`,
		raceID, driverID)
	return err
}

// SetLiveStatus updates the status (and started_ms) of a live race.
func (s *PgStore) SetLiveStatus(ctx context.Context, raceID string, status lobby.RaceStatus, startedMs int64) error {
	now := time.Now().UnixMilli()
	_, err := s.pool.Exec(ctx, `
		UPDATE races
		SET status = $2, started_ms = $3, updated_ms = $4
		WHERE id = $1 AND status IN ('lobby','countdown','racing')`,
		raceID, string(status), startedMs, now)
	return err
}

// ListLivePaged returns one keyset page of live races.
func (s *PgStore) ListLivePaged(ctx context.Context, statuses []string, trackID string, cur Cursor, limit int) ([]lobby.RaceMeta, error) {
	if limit <= 0 {
		limit = 50
	}
	args := []any{}
	conds := []string{"status IN ('lobby','countdown','racing')"}
	if len(statuses) > 0 {
		args = append(args, statuses)
		conds = append(conds, fmt.Sprintf("status = ANY($%d)", len(args)))
	}
	if trackID != "" {
		args = append(args, trackID)
		conds = append(conds, fmt.Sprintf("track_id = $%d", len(args)))
	}
	if !cur.IsZero() {
		args = append(args, cur.Ms, cur.ID)
		conds = append(conds, fmt.Sprintf("(COALESCE(started_ms, created_ms), id) < ($%d, $%d)", len(args)-1, len(args)))
	}
	args = append(args, limit+1)
	q := `SELECT id, name, track_id, max_cars, laps, time_limit_s, status,
	             created_ms, started_ms
	      FROM races
	      WHERE ` + joinAnd(conds) + `
	      ORDER BY COALESCE(started_ms, created_ms) DESC, id ASC
	      LIMIT $` + fmt.Sprintf("%d", len(args))
	rows, err := s.pool.Query(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]lobby.RaceMeta, 0)
	for rows.Next() {
		var r lobby.RaceMeta
		var status string
		if err := rows.Scan(&r.ID, &r.Name, &r.TrackID, &r.MaxCars, &r.Laps, &r.TimeLimitS,
			&status, &r.CreatedMs, &r.StartedMs); err != nil {
			return nil, err
		}
		r.Status = lobby.RaceStatus(status)
		out = append(out, r)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	for i := range out {
		ids, err := s.listDriverIDs(ctx, out[i].ID)
		if err != nil {
			return nil, err
		}
		out[i].DriverIDs = ids
	}
	return out, nil
}

// ListLiveUpcoming returns up to limit live races in (lobby, countdown)
// ordered soonest first.
func (s *PgStore) ListLiveUpcoming(ctx context.Context, limit int) ([]lobby.RaceMeta, error) {
	if limit <= 0 {
		limit = 3
	}
	rows, err := s.pool.Query(ctx, `
		SELECT id, name, track_id, max_cars, laps, time_limit_s, status,
		       created_ms, started_ms
		FROM races
		WHERE status IN ('lobby', 'countdown')
		ORDER BY COALESCE(started_ms, created_ms) ASC, id ASC
		LIMIT $1`, limit+1)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]lobby.RaceMeta, 0)
	for rows.Next() {
		var r lobby.RaceMeta
		var status string
		if err := rows.Scan(&r.ID, &r.Name, &r.TrackID, &r.MaxCars, &r.Laps, &r.TimeLimitS,
			&status, &r.CreatedMs, &r.StartedMs); err != nil {
			return nil, err
		}
		r.Status = lobby.RaceStatus(status)
		out = append(out, r)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	for i := range out {
		ids, err := s.listDriverIDs(ctx, out[i].ID)
		if err != nil {
			return nil, err
		}
		out[i].DriverIDs = ids
	}
	return out, nil
}

// GetLive fetches a single live race.
func (s *PgStore) GetLive(ctx context.Context, id string) (lobby.RaceMeta, error) {
	row := s.pool.QueryRow(ctx, `
		SELECT id, name, track_id, max_cars, laps, time_limit_s, status,
		       created_ms, started_ms
		FROM races WHERE id = $1 AND status IN ('lobby','countdown','racing')`, id)
	var r lobby.RaceMeta
	var status string
	if err := row.Scan(&r.ID, &r.Name, &r.TrackID, &r.MaxCars, &r.Laps, &r.TimeLimitS,
		&status, &r.CreatedMs, &r.StartedMs); err != nil {
		return lobby.RaceMeta{}, err
	}
	r.Status = lobby.RaceStatus(status)
	ids, err := s.listDriverIDs(ctx, id)
	if err != nil {
		return lobby.RaceMeta{}, err
	}
	r.DriverIDs = ids
	return r, nil
}

// ListAllRaces returns every row in the races table (live+finished).
// Used by RestoreFromDB to rehydrate the lobby.
func (s *PgStore) ListAllRaces(ctx context.Context) ([]lobby.RaceMeta, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id, name, track_id, max_cars, laps, time_limit_s, status,
		       created_ms, started_ms
		FROM races
		WHERE status IN ('lobby','countdown','racing')
		ORDER BY created_ms ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]lobby.RaceMeta, 0)
	for rows.Next() {
		var r lobby.RaceMeta
		var status string
		if err := rows.Scan(&r.ID, &r.Name, &r.TrackID, &r.MaxCars, &r.Laps, &r.TimeLimitS,
			&status, &r.CreatedMs, &r.StartedMs); err != nil {
			return nil, err
		}
		r.Status = lobby.RaceStatus(status)
		out = append(out, r)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	for i := range out {
		ids, err := s.listDriverIDs(ctx, out[i].ID)
		if err != nil {
			return nil, err
		}
		out[i].DriverIDs = ids
	}
	return out, nil
}

func (s *PgStore) listDriverIDs(ctx context.Context, raceID string) ([]string, error) {
	rows, err := s.pool.Query(ctx,
		`SELECT driver_id FROM race_drivers WHERE race_id = $1 ORDER BY slot ASC, joined_ms ASC`,
		raceID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]string, 0)
	for rows.Next() {
		var id string
		if err := rows.Scan(&id); err != nil {
			return nil, err
		}
		out = append(out, id)
	}
	return out, rows.Err()
}

// UpsertLobbyDriver mirrors a lobby.DriverMeta row.
func (s *PgStore) UpsertLobbyDriver(ctx context.Context, d lobby.DriverMeta) error {
	_, err := s.pool.Exec(ctx, `
		INSERT INTO lobby_drivers
		    (driver_id, name, nickname, avatar_url, clan_id, clan_tag,
		     status, current_race_id, connected_ms, last_seen_ms, car_id)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
		ON CONFLICT (driver_id) DO UPDATE SET
		    name = EXCLUDED.name,
		    nickname = EXCLUDED.nickname,
		    avatar_url = EXCLUDED.avatar_url,
		    clan_id = EXCLUDED.clan_id,
		    clan_tag = EXCLUDED.clan_tag,
		    status = EXCLUDED.status,
		    current_race_id = EXCLUDED.current_race_id,
		    last_seen_ms = EXCLUDED.last_seen_ms,
		    car_id = EXCLUDED.car_id`,
		d.ID, d.Name, d.Nickname, d.AvatarURL, d.ClanID, d.ClanTag,
		string(d.Status), d.RaceID, d.ConnectedMs, d.LastSeenMs, d.CarID)
	if err != nil {
		return fmt.Errorf("upsert lobby driver %s: %w", d.ID, err)
	}
	return nil
}

// DeleteLobbyDriver removes a lobby driver row.
func (s *PgStore) DeleteLobbyDriver(ctx context.Context, driverID string) error {
	_, err := s.pool.Exec(ctx, `DELETE FROM lobby_drivers WHERE driver_id = $1`, driverID)
	return err
}

// ListLobbyDrivers returns all lobby drivers.
func (s *PgStore) ListLobbyDrivers(ctx context.Context) ([]lobby.DriverMeta, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT driver_id, name, nickname, avatar_url, clan_id, clan_tag,
		       status, current_race_id, connected_ms, last_seen_ms, car_id
		FROM lobby_drivers ORDER BY last_seen_ms DESC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]lobby.DriverMeta, 0)
	for rows.Next() {
		var d lobby.DriverMeta
		var status string
		if err := rows.Scan(&d.ID, &d.Name, &d.Nickname, &d.AvatarURL, &d.ClanID, &d.ClanTag,
			&status, &d.RaceID, &d.ConnectedMs, &d.LastSeenMs, &d.CarID); err != nil {
			return nil, err
		}
		d.Status = lobby.DriverStatus(status)
		out = append(out, d)
	}
	return out, rows.Err()
}

// ---------------------------------------------------------------------------
// finished_races
// ---------------------------------------------------------------------------

// InsertFinished upserts a finished race row and replaces its
// race_drivers entries in a single transaction. Per-driver outcome
// (total_time_ms, best_lap_ms, position) lives on race_drivers;
// the race row itself carries only metadata.
func (s *PgStore) InsertFinished(ctx context.Context, r FinishedRace) error {
	_, err := s.pool.Exec(ctx, `
		INSERT INTO races
		    (id, name, track_id, max_cars, laps, time_limit_s,
		     status, created_ms, started_ms, finished_ms, duration_ms,
		     total_laps, total_drivers)
		VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
		ON CONFLICT (id) DO UPDATE SET
		    name = EXCLUDED.name,
		    status = EXCLUDED.status,
		    finished_ms = EXCLUDED.finished_ms,
		    duration_ms = EXCLUDED.duration_ms,
		    total_laps = EXCLUDED.total_laps,
		    total_drivers = EXCLUDED.total_drivers`,
		r.ID, r.Name, r.TrackID, r.MaxCars, r.Laps, r.TimeLimitS,
		r.Status, r.CreatedMs, r.StartedMs, r.FinishedMs, r.DurationMs,
		r.TotalLaps, r.TotalDrivers)
	if err != nil {
		return fmt.Errorf("insert finished race %s: %w", r.ID, err)
	}
	// Replace race_drivers with the provided list atomically.
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback(ctx)
	if _, err := tx.Exec(ctx, `DELETE FROM race_drivers WHERE race_id = $1`, r.ID); err != nil {
		return fmt.Errorf("clear race_drivers for %s: %w", r.ID, err)
	}
	// Build a map from driver_id -> DriverResult for lookup.
	resByDriver := make(map[string]DriverResult, len(r.Results))
	for _, dr := range r.Results {
		resByDriver[dr.DriverID] = dr
	}
	for i, did := range r.DriverIDs {
		dr, ok := resByDriver[did]
		_ = ok // missing result: total_time_ms=0, best_lap_ms=0, position=NULL
		var totalTime, bestLap int64
		var pos *int
		if ok {
			totalTime = dr.TotalTimeMs
			bestLap = dr.BestLapMs
			pos = dr.Position
		}
		if _, err := tx.Exec(ctx, `
			INSERT INTO race_drivers
			    (race_id, driver_id, slot, joined_ms,
			     total_time_ms, best_lap_ms, position)
			VALUES ($1, $2, $3, $4, $5, $6, $7)`,
			r.ID, did, i, r.CreatedMs, totalTime, bestLap, pos); err != nil {
			return fmt.Errorf("insert race_drivers %s: %w", r.ID, err)
		}
	}
	if err := tx.Commit(ctx); err != nil {
		return fmt.Errorf("commit race_drivers: %w", err)
	}
	return nil
}

// ListFinished returns finished races matching the filter using keyset
// pagination on (finished_ms DESC, id DESC). The cursor's Ms is the
// last finished_ms from the previous page; rows strictly older are
// returned. Tie-breaker on id.
func (s *PgStore) ListFinished(ctx context.Context, trackID string, cur Cursor, limit int) ([]FinishedRace, error) {
	if limit <= 0 {
		limit = 50
	}
	args := []any{}
	conds := []string{"status IN ('finished','cancelled')"}
	if !cur.IsZero() {
		args = append(args, cur.Ms, cur.ID)
		conds = append(conds, fmt.Sprintf("(finished_ms, id) < ($%d, $%d)", len(args)-1, len(args)))
	}
	if trackID != "" {
		args = append(args, trackID)
		conds = append(conds, fmt.Sprintf("track_id = $%d", len(args)))
	}
	args = append(args, limit+1)
	q := `SELECT id, name, track_id, max_cars, laps, time_limit_s,
	             status, created_ms, started_ms, finished_ms, duration_ms,
	             total_laps, total_drivers
	      FROM races
	      WHERE ` + joinAnd(conds) + `
	      ORDER BY finished_ms DESC, id DESC
	      LIMIT $` + fmt.Sprintf("%d", len(args))
	rows, err := s.pool.Query(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("list finished: %w", err)
	}
	defer rows.Close()
	return s.scanFinished(ctx, rows)
}

// CountRaces returns the total number of races matching the status filter and trackID.
func (s *PgStore) CountRaces(ctx context.Context, statuses []string, trackID string) (int, error) {
	args := []any{}
	conds := []string{"1=1"}
	if len(statuses) > 0 {
		placeholders := make([]string, len(statuses))
		for i, st := range statuses {
			args = append(args, st)
			placeholders[i] = fmt.Sprintf("$%d", len(args))
		}
		conds = append(conds, fmt.Sprintf("status IN (%s)", strings.Join(placeholders, ",")))
	}
	if trackID != "" {
		args = append(args, trackID)
		conds = append(conds, fmt.Sprintf("track_id = $%d", len(args)))
	}
	q := `SELECT COUNT(*) FROM races WHERE ` + joinAnd(conds)
	var count int
	err := s.pool.QueryRow(ctx, q, args...).Scan(&count)
	if err != nil {
		return 0, fmt.Errorf("count races: %w", err)
	}
	return count, nil
}

// scanFinished reads the rows from the SELECT above, then hydrates
// DriverIDs and the per-driver Results from race_drivers. The
// Winner* and Podium fields are derived from Results.
func (s *PgStore) scanFinished(ctx context.Context, rows pgx.Rows) ([]FinishedRace, error) {
	out := make([]FinishedRace, 0)
	for rows.Next() {
		var r FinishedRace
		if err := rows.Scan(
			&r.ID, &r.Name, &r.TrackID,
			&r.MaxCars, &r.Laps, &r.TimeLimitS, &r.Status,
			&r.CreatedMs, &r.StartedMs, &r.FinishedMs, &r.DurationMs,
			&r.TotalLaps, &r.TotalDrivers,
		); err != nil {
			return nil, err
		}
		if err := s.hydrateFinished(ctx, &r); err != nil {
			return nil, err
		}
		out = append(out, r)
	}
	return out, rows.Err()
}

// hydrateFinished pulls race_drivers for the given race into Results
// and derives the Winner* and Podium fields.
func (s *PgStore) hydrateFinished(ctx context.Context, r *FinishedRace) error {
	rows, err := s.pool.Query(ctx, `
		SELECT rd.driver_id, rd.total_time_ms, rd.best_lap_ms, rd.position, d.name, d.nickname, d.avatar_url, d.clan_id
		FROM race_drivers rd left join drivers d on rd.driver_id = d.id
		WHERE race_id = $1
		ORDER BY slot ASC, joined_ms ASC`, r.ID)
	if err != nil {
		return fmt.Errorf("hydrate race_drivers %s: %w", r.ID, err)
	}
	defer rows.Close()

	r.Results = make([]DriverResult, 0)
	r.DriverIDs = make([]string, 0)
	r.Podium = make([]PodiumEntry, 0)
	for rows.Next() {
		var dr DriverResult
		var pos *int
		var name, nick, avatar, clanID *string
		if err := rows.Scan(
			&dr.DriverID, &dr.TotalTimeMs, &dr.BestLapMs, &pos,
			&name, &nick, &avatar, &clanID,
		); err != nil {
			return err
		}
		dr.Position = pos
		if name != nil {
			dr.Name = *name
		} else {
			dr.Name = dr.DriverID
		}
		if nick != nil {
			dr.Nickname = *nick
		}
		if avatar != nil {
			dr.AvatarUrl = *avatar
		}
		if clanID != nil {
			dr.ClanID = *clanID
		}
		r.Results = append(r.Results, dr)
		r.DriverIDs = append(r.DriverIDs, dr.DriverID)
	}
	if err := rows.Err(); err != nil {
		return err
	}
	// Derive winner (lowest total_time_ms among rows with time > 0).
	var bestTotal int64 = -1
	for _, dr := range r.Results {
		if dr.TotalTimeMs <= 0 {
			continue
		}
		if bestTotal == -1 || dr.TotalTimeMs < bestTotal {
			bestTotal = dr.TotalTimeMs
			r.WinnerDriverID = dr.DriverID
			r.WinnerName = dr.Name
		}
		if dr.BestLapMs > 0 && (r.BestLapMs == 0 || dr.BestLapMs < r.BestLapMs) {
			r.BestLapMs = dr.BestLapMs
		}
	}
	// Derive podium: top-3 drivers by total_time_ms (> 0) ASC.
	type row struct {
		id     string
		t      int64
		best   int64
		name   string
		nick   string
		avatar string
		clanID string
	}
	var sorted []row
	for _, dr := range r.Results {
		if dr.TotalTimeMs <= 0 {
			continue
		}
		sorted = append(sorted, row{
			id:     dr.DriverID,
			t:      dr.TotalTimeMs,
			best:   dr.BestLapMs,
			name:   dr.Name,
			nick:   dr.Nickname,
			avatar: dr.AvatarUrl,
			clanID: dr.ClanID,
		})
	}
	for i := 1; i < len(sorted); i++ {
		for j := i; j > 0 && sorted[j-1].t > sorted[j].t; j-- {
			sorted[j-1], sorted[j] = sorted[j], sorted[j-1]
		}
	}
	for i := 0; i < len(sorted) && i < 3; i++ {
		r.Podium = append(r.Podium, PodiumEntry{
			Position:    i + 1,
			DriverID:    sorted[i].id,
			Name:        sorted[i].name,
			TotalTimeMs: sorted[i].t,
			Nickname:    sorted[i].nick,
			AvatarUrl:   sorted[i].avatar,
			ClanID:      sorted[i].clanID,
		})
	}
	return nil
}

func joinAnd(parts []string) string {
	out := ""
	for i, p := range parts {
		if i > 0 {
			out += " AND "
		}
		out += p
	}
	return out
}

// ---------------------------------------------------------------------------
// race_plans
// ---------------------------------------------------------------------------

// CreatePlan inserts a new race plan.
func (s *PgStore) CreatePlan(ctx context.Context, p RacePlan) error {
	now := time.Now().UnixMilli()
	if p.CreatedMs == 0 {
		p.CreatedMs = now
	}
	p.UpdatedMs = now
	if p.NextFireMs == 0 {
		p.NextFireMs = p.StartAtMs
	}
	_, err := s.pool.Exec(ctx, `
		INSERT INTO race_plans
		    (id, name, track_id, max_cars, laps, time_limit_s,
		     start_at_ms, interval_s, count,
		     enabled, created_ms, updated_ms, next_fire_ms, fires_done)
		VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14)`,
		p.ID, p.Name, p.TrackID, p.MaxCars, p.Laps, p.TimeLimitS,
		p.StartAtMs, p.IntervalS, p.Count,
		p.Enabled, p.CreatedMs, p.UpdatedMs, p.NextFireMs, p.FiresDone)
	if err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
			return fmt.Errorf("%w: plan %s", ErrAlreadyExists, p.ID)
		}
		return fmt.Errorf("insert plan: %w", err)
	}
	return nil
}

// GetPlan loads a plan by id.
func (s *PgStore) GetPlan(ctx context.Context, id string) (RacePlan, error) {
	row := s.pool.QueryRow(ctx, `
		SELECT id, name, track_id, max_cars, laps, time_limit_s,
		       start_at_ms, interval_s, count,
		       enabled, created_ms, updated_ms, next_fire_ms, fires_done
		FROM race_plans WHERE id = $1`, id)
	var p RacePlan
	if err := row.Scan(
		&p.ID, &p.Name, &p.TrackID, &p.MaxCars, &p.Laps, &p.TimeLimitS,
		&p.StartAtMs, &p.IntervalS, &p.Count,
		&p.Enabled, &p.CreatedMs, &p.UpdatedMs, &p.NextFireMs, &p.FiresDone,
	); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return RacePlan{}, ErrNotFound
		}
		return RacePlan{}, err
	}
	return p, nil
}

// ListPlans returns plans in ascending start order, keyset-paginated.
func (s *PgStore) ListPlans(ctx context.Context, cur Cursor, limit int) ([]RacePlan, error) {
	if limit <= 0 {
		limit = 50
	}
	args := []any{}
	conds := []string{"1=1"}
	if !cur.IsZero() {
		args = append(args, cur.Ms, cur.ID)
		conds = append(conds, fmt.Sprintf("(start_at_ms, id) > ($%d, $%d)", len(args)-1, len(args)))
	}
	args = append(args, limit+1)
	q := `SELECT id, name, track_id, max_cars, laps, time_limit_s,
	             start_at_ms, interval_s, count,
	             enabled, created_ms, updated_ms, next_fire_ms, fires_done
	      FROM race_plans
	      WHERE ` + joinAnd(conds) + `
	      ORDER BY start_at_ms ASC, id ASC
	      LIMIT $` + fmt.Sprintf("%d", len(args))
	rows, err := s.pool.Query(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("list plans: %w", err)
	}
	defer rows.Close()
	return scanPlans(rows)
}

func scanPlans(rows pgx.Rows) ([]RacePlan, error) {
	out := make([]RacePlan, 0)
	for rows.Next() {
		var p RacePlan
		if err := rows.Scan(
			&p.ID, &p.Name, &p.TrackID, &p.MaxCars, &p.Laps, &p.TimeLimitS,
			&p.StartAtMs, &p.IntervalS, &p.Count,
			&p.Enabled, &p.CreatedMs, &p.UpdatedMs, &p.NextFireMs, &p.FiresDone,
		); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// CountPlans returns the total number of race plans.
func (s *PgStore) CountPlans(ctx context.Context) (int, error) {
	var count int
	err := s.pool.QueryRow(ctx, "SELECT COUNT(*) FROM race_plans").Scan(&count)
	if err != nil {
		return 0, fmt.Errorf("count plans: %w", err)
	}
	return count, nil
}

// DeletePlan removes a plan by id.
func (s *PgStore) DeletePlan(ctx context.Context, id string) error {
	tag, err := s.pool.Exec(ctx, `DELETE FROM race_plans WHERE id = $1`, id)
	if err != nil {
		return fmt.Errorf("delete plan: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

// SetPlanEnabled toggles the enabled flag.
func (s *PgStore) SetPlanEnabled(ctx context.Context, id string, enabled bool) error {
	tag, err := s.pool.Exec(ctx,
		`UPDATE race_plans SET enabled = $2, updated_ms = $3 WHERE id = $1`,
		id, enabled, time.Now().UnixMilli())
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

// AdvancePlan moves the next_fire_ms cursor after a successful materialise
// and increments fires_done. If count is reached, disables the plan.
func (s *PgStore) AdvancePlan(ctx context.Context, id string, nextFireMs int64) error {
	_, err := s.pool.Exec(ctx, `
		UPDATE race_plans
		SET next_fire_ms = $2,
		    fires_done   = fires_done + 1,
		    updated_ms   = $3,
		    enabled      = CASE
		        WHEN count > 0 AND fires_done + 1 >= count THEN FALSE
		        ELSE enabled
		    END
		WHERE id = $1`,
		id, nextFireMs, time.Now().UnixMilli())
	return err
}

// DuePlans returns plans whose next_fire_ms is <= now.
func (s *PgStore) DuePlans(ctx context.Context, nowMs int64, limit int) ([]RacePlan, error) {
	if limit <= 0 {
		limit = 16
	}
	rows, err := s.pool.Query(ctx, `
		SELECT id, name, track_id, max_cars, laps, time_limit_s,
		       start_at_ms, interval_s, count,
		       enabled, created_ms, updated_ms, next_fire_ms, fires_done
		FROM race_plans
		WHERE enabled AND next_fire_ms <= $1
		ORDER BY next_fire_ms ASC
		LIMIT $2`, nowMs, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return scanPlans(rows)
}

// ---------------------------------------------------------------------------
// queue
// ---------------------------------------------------------------------------

// Enqueue adds (driver, race) to the queue. Idempotent: returns the existing
// entry if present.
func (s *PgStore) Enqueue(ctx context.Context, driverID, raceID, planID string) (QueueEntry, error) {
	if driverID == "" || raceID == "" {
		return QueueEntry{}, fmt.Errorf("%w: driver_id and race_id required", ErrInvalidInput)
	}
	now := time.Now().UnixMilli()
	_, err := s.pool.Exec(ctx, `
		INSERT INTO race_queue (driver_id, race_id, plan_id, enqueued_ms)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (driver_id, race_id) DO NOTHING`,
		driverID, raceID, planID, now)
	if err != nil {
		return QueueEntry{}, fmt.Errorf("enqueue: %w", err)
	}
	row := s.pool.QueryRow(ctx, `
		SELECT driver_id, race_id, plan_id, enqueued_ms
		FROM race_queue WHERE driver_id = $1 AND race_id = $2`,
		driverID, raceID)
	var q QueueEntry
	if err := row.Scan(&q.DriverID, &q.RaceID, &q.PlanID, &q.EnqueuedMs); err != nil {
		return QueueEntry{}, err
	}
	return q, nil
}

// Dequeue removes (driver, race) entry.
func (s *PgStore) Dequeue(ctx context.Context, driverID, raceID string) error {
	tag, err := s.pool.Exec(ctx,
		`DELETE FROM race_queue WHERE driver_id = $1 AND race_id = $2`,
		driverID, raceID)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

// ListQueueByDriver returns queue entries for a driver.
func (s *PgStore) ListQueueByDriver(ctx context.Context, driverID string) ([]QueueEntry, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT driver_id, race_id, plan_id, enqueued_ms
		FROM race_queue WHERE driver_id = $1
		ORDER BY enqueued_ms ASC`, driverID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]QueueEntry, 0)
	for rows.Next() {
		var q QueueEntry
		if err := rows.Scan(&q.DriverID, &q.RaceID, &q.PlanID, &q.EnqueuedMs); err != nil {
			return nil, err
		}
		out = append(out, q)
	}
	return out, rows.Err()
}

// ListQueueByRace returns all queue entries for a given race, oldest first.
func (s *PgStore) ListQueueByRace(ctx context.Context, raceID string) ([]QueueEntry, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT driver_id, race_id, plan_id, enqueued_ms
		FROM race_queue WHERE race_id = $1
		ORDER BY enqueued_ms ASC`, raceID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]QueueEntry, 0)
	for rows.Next() {
		var q QueueEntry
		if err := rows.Scan(&q.DriverID, &q.RaceID, &q.PlanID, &q.EnqueuedMs); err != nil {
			return nil, err
		}
		out = append(out, q)
	}
	return out, rows.Err()
}

// CountQueueByRace returns the queue length for a race.
func (s *PgStore) CountQueueByRace(ctx context.Context, raceID string) (int, error) {
	var n int
	row := s.pool.QueryRow(ctx,
		`SELECT COUNT(*) FROM race_queue WHERE race_id = $1`, raceID)
	if err := row.Scan(&n); err != nil {
		return 0, err
	}
	return n, nil
}

// ToLobbyMeta converts a finished race to a wire-friendly RaceMeta for
// uniform presentation alongside live races. Podium is dropped here;
// the wire type carries the full PodiumEntry list separately.
func (f FinishedRace) ToLobbyMeta() lobby.RaceMeta {
	return lobby.RaceMeta{
		ID:         f.ID,
		Name:       f.Name,
		TrackID:    f.TrackID,
		MaxCars:    f.MaxCars,
		Laps:       f.Laps,
		TimeLimitS: f.TimeLimitS,
		DriverIDs:  append([]string(nil), f.DriverIDs...),
		Status:     lobby.RaceStatus(f.Status),
		CreatedMs:  f.CreatedMs,
		StartedMs:  f.StartedMs,
	}
}