package httpapi

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"math"
	"net/http"
	"strings"

	"git.yeij.top/AskaEth/Scoreboard/server/internal/domain"
	"git.yeij.top/AskaEth/Scoreboard/server/internal/middleware"
)

// ---------- events ----------

const eventColumns = `id, sport_id, code, name, event_type, result_mode, result_type, compare,
	record_eligible, scored, multiplier, status, scheduled_at, venue, sort_order, remark, avg_mode`

func scanEvent(row interface{ Scan(...any) error }) (eventDTO, error) {
	var (
		e                        eventDTO
		scheduledAt, venue, note sql.NullString
	)
	err := row.Scan(&e.ID, &e.SportID, &e.Code, &e.Name, &e.EventType, &e.ResultMode, &e.ResultType,
		&e.Compare, &e.RecordEligible, &e.Scored, &e.Multiplier, &e.Status,
		&scheduledAt, &venue, &e.SortOrder, &note, &e.AvgMode)
	e.ScheduledAt = strPtr(scheduledAt)
	e.Venue = strPtr(venue)
	e.Remark = strPtr(note)
	return e, err
}

func (s *server) listEvents(ctx context.Context, sportID int64) ([]eventDTO, error) {
	query := `SELECT ` + eventColumns + ` FROM events`
	args := []any{}
	if sportID > 0 {
		query += ` WHERE sport_id = ?`
		args = append(args, sportID)
	}
	query += ` ORDER BY sort_order, code`

	rows, err := s.ev.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]eventDTO, 0)
	for rows.Next() {
		e, err := scanEvent(rows)
		if err != nil {
			return nil, internal(err)
		}
		out = append(out, e)
	}
	return out, rows.Err()
}

func (s *server) getEvent(ctx context.Context, id int64) (eventDTO, error) {
	e, err := eventByIDQ(ctx, s.ev, id)
	if err != nil {
		return eventDTO{}, err
	}
	cats, err := s.listCategories(ctx, id)
	if err != nil {
		return eventDTO{}, err
	}
	chs, err := s.listChannels(ctx, id)
	if err != nil {
		return eventDTO{}, err
	}
	e.Categories = cats
	e.Channels = chs
	return e, nil
}

// eventByIDQ 在给定连接/事务内读取小项（不含组别/通道），供写事务内构造 change_log 载荷复用。
func eventByIDQ(ctx context.Context, q queryer, id int64) (eventDTO, error) {
	e, err := scanEvent(q.QueryRowContext(ctx, `SELECT `+eventColumns+` FROM events WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return eventDTO{}, notFound("小项不存在")
	}
	if err != nil {
		return eventDTO{}, internal(err)
	}
	return e, nil
}

func (s *server) createEvent(ctx context.Context, in eventDTO) (eventDTO, error) {
	if in.SportID == 0 || strings.TrimSpace(in.Code) == "" || strings.TrimSpace(in.Name) == "" {
		return eventDTO{}, badRequest("sportId、code、name 必填", nil)
	}
	avgMode, err := normalizeAvgMode(in.AvgMode)
	if err != nil {
		return eventDTO{}, err
	}
	eventType, err := normalizeEventType(in.EventType)
	if err != nil {
		return eventDTO{}, err
	}
	resultMode, err := normalizeResultMode(in.ResultMode)
	if err != nil {
		return eventDTO{}, err
	}
	resultType, err := normalizeResultType(in.ResultType)
	if err != nil {
		return eventDTO{}, err
	}
	compare, err := normalizeCompare(in.Compare)
	if err != nil {
		return eventDTO{}, err
	}
	status, err := normalizeEventStatus(in.Status)
	if err != nil {
		return eventDTO{}, err
	}
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return eventDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`INSERT INTO events (sport_id, code, name, event_type, result_mode, result_type, compare,
		        record_eligible, scored, multiplier, status, scheduled_at, venue, sort_order, remark, avg_mode)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		in.SportID, in.Code, in.Name,
		eventType, resultMode, resultType, compare,
		in.RecordEligible, in.Scored, multiplierOrOne(in.Multiplier), status,
		nullStr(in.ScheduledAt), nullStr(in.Venue), in.SortOrder, nullStr(in.Remark), avgMode)
	if isUniqueViolation(err) {
		return eventDTO{}, conflict("小项编码已存在")
	}
	if isForeignKeyViolation(err) {
		return eventDTO{}, badRequest("sportId 不存在", nil)
	}
	if err != nil {
		return eventDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return eventDTO{}, internal(err)
	}
	// 项目增删改要推给大屏，否则底栏/分项页拿不到新项目。
	if err := s.bumpEvent(ctx, tx, id); err != nil {
		return eventDTO{}, err
	}
	if err := tx.Commit(); err != nil {
		return eventDTO{}, internal(err)
	}
	return s.getEvent(ctx, id)
}

func (s *server) updateEvent(ctx context.Context, id int64, in eventDTO) (eventDTO, error) {
	avgMode, err := normalizeAvgMode(in.AvgMode)
	if err != nil {
		return eventDTO{}, err
	}
	eventType, err := normalizeEventType(in.EventType)
	if err != nil {
		return eventDTO{}, err
	}
	resultMode, err := normalizeResultMode(in.ResultMode)
	if err != nil {
		return eventDTO{}, err
	}
	resultType, err := normalizeResultType(in.ResultType)
	if err != nil {
		return eventDTO{}, err
	}
	compare, err := normalizeCompare(in.Compare)
	if err != nil {
		return eventDTO{}, err
	}
	status, err := normalizeEventStatus(in.Status)
	if err != nil {
		return eventDTO{}, err
	}
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return eventDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`UPDATE events SET sport_id = ?, code = ?, name = ?, event_type = ?, result_mode = ?,
		        result_type = ?, compare = ?, record_eligible = ?, scored = ?, multiplier = ?,
		        status = ?, scheduled_at = ?, venue = ?, sort_order = ?, remark = ?, avg_mode = ?
		  WHERE id = ?`,
		in.SportID, in.Code, in.Name,
		eventType, resultMode, resultType, compare,
		in.RecordEligible, in.Scored, multiplierOrOne(in.Multiplier), status,
		nullStr(in.ScheduledAt), nullStr(in.Venue), in.SortOrder, nullStr(in.Remark), avgMode, id)
	if isUniqueViolation(err) {
		return eventDTO{}, conflict("小项编码已存在")
	}
	if isForeignKeyViolation(err) {
		return eventDTO{}, badRequest("sportId 不存在", nil)
	}
	if err != nil {
		return eventDTO{}, internal(err)
	}
	if err := requireChanges(res, "小项不存在"); err != nil {
		return eventDTO{}, err
	}
	if err := s.bumpEvent(ctx, tx, id); err != nil {
		return eventDTO{}, err
	}
	if err := tx.Commit(); err != nil {
		return eventDTO{}, internal(err)
	}
	return s.getEvent(ctx, id)
}

// bumpEvent 在写事务内推送小项变更；组别/通道的改动同样以本小项为载体。
func (s *server) bumpEvent(ctx context.Context, tx *sql.Tx, eventID int64) error {
	ev, err := eventByIDQ(ctx, tx, eventID)
	if err != nil {
		return err
	}
	return bumpVersion(ctx, tx, "events", eventID, "upsert", ev, middleware.User(ctx).ID)
}

func (s *server) deleteEvent(ctx context.Context, id int64) error {
	has, err := exists(ctx, s.ev, `SELECT 1 FROM entries WHERE event_id = ? LIMIT 1`, id)
	if err != nil {
		return internal(err)
	}
	if has {
		return conflict("小项已有报名数据，不能删除")
	}
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return internal(err)
	}
	defer func() { _ = tx.Rollback() }()
	for _, stmt := range []string{
		`DELETE FROM event_score_channels WHERE event_id = ?`,
		`DELETE FROM event_categories WHERE event_id = ?`,
		`DELETE FROM events WHERE id = ?`,
	} {
		if _, err := tx.ExecContext(ctx, stmt, id); err != nil {
			return internal(err)
		}
	}
	if err := bumpVersion(ctx, tx, "events", id, "void", map[string]any{"id": id}, middleware.User(ctx).ID); err != nil {
		return err
	}
	if err := tx.Commit(); err != nil {
		return internal(err)
	}
	return nil
}

func multiplierOrOne(v float64) float64 {
	if v <= 0 {
		return 1
	}
	return v
}

// normalizeAvgMode 校验团体成绩的平均值口径；空值按 valid（与库中默认值一致）。
func normalizeAvgMode(v string) (string, error) {
	switch v {
	case "":
		return string(domain.AvgModeValid), nil
	case string(domain.AvgModeValid), string(domain.AvgModeAll):
		return v, nil
	default:
		return "", badRequest("avgMode 只能是 valid / all", v)
	}
}

// ---------- categories ----------

func (s *server) listCategories(ctx context.Context, eventID int64) ([]categoryDTO, error) {
	rows, err := s.ev.QueryContext(ctx,
		`SELECT id, event_id, name, multiplier, gender, age_min, age_max, sort_order
		   FROM event_categories WHERE event_id = ? ORDER BY sort_order, id`, eventID)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]categoryDTO, 0)
	for rows.Next() {
		var (
			c              categoryDTO
			gender         sql.NullString
			ageMin, ageMax sql.NullInt64
		)
		if err := rows.Scan(&c.ID, &c.EventID, &c.Name, &c.Multiplier, &gender, &ageMin, &ageMax, &c.SortOrder); err != nil {
			return nil, internal(err)
		}
		c.Gender = strPtr(gender)
		c.AgeMin = intPtr(ageMin)
		c.AgeMax = intPtr(ageMax)
		out = append(out, c)
	}
	return out, rows.Err()
}

// replaceCategories 整体替换某小项的组别（devdocs/05 约定）。已有报名数据时拒绝替换，
// 否则外键会把历史报名项一并带走。
//
// 被拦下的只是「增删组别」：改名 / 改年龄 / 改性别 / 改权重走 updateCategory 就地更新，
// 所以这里的文案要点明范围，别让只改了个名字的人以为改名也不许。
func (s *server) replaceCategories(ctx context.Context, eventID int64, in []categoryDTO) ([]categoryDTO, error) {
	has, err := exists(ctx, s.ev,
		`SELECT 1 FROM entries e JOIN event_categories c ON c.id = e.category_id
		  WHERE c.event_id = ? LIMIT 1`, eventID)
	if err != nil {
		return nil, internal(err)
	}
	if has {
		return nil, conflict("该项目已有报名数据，不能新增或删除组别；改名、改年龄、改性别、改权重可以直接保存")
	}

	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	if _, err := tx.ExecContext(ctx, `DELETE FROM event_categories WHERE event_id = ?`, eventID); err != nil {
		return nil, internal(err)
	}
	for i, c := range in {
		if strings.TrimSpace(c.Name) == "" {
			return nil, badRequest("组别 name 必填", i)
		}
		if _, err := tx.ExecContext(ctx,
			`INSERT INTO event_categories (event_id, name, multiplier, gender, age_min, age_max, sort_order)
			 VALUES (?, ?, ?, ?, ?, ?, ?)`,
			eventID, c.Name, multiplierOrOne(c.Multiplier), nullStr(c.Gender), nullInt(c.AgeMin), nullInt(c.AgeMax), c.SortOrder); err != nil {
			if isUniqueViolation(err) {
				return nil, conflict("组别名称重复：" + c.Name)
			}
			return nil, internal(err)
		}
	}
	if err := s.bumpEvent(ctx, tx, eventID); err != nil {
		return nil, err
	}
	if err := tx.Commit(); err != nil {
		return nil, internal(err)
	}
	return s.listCategories(ctx, eventID)
}

// getCategory 读单个组别，并校验它属于该小项。不属于（或用别的小项 id 来探）
// 一律按「组别不存在」处理，不给跨小项改名的机会。
func (s *server) getCategory(ctx context.Context, eventID, categoryID int64) (categoryDTO, error) {
	var (
		c              categoryDTO
		gender         sql.NullString
		ageMin, ageMax sql.NullInt64
	)
	err := s.ev.QueryRowContext(ctx,
		`SELECT id, event_id, name, multiplier, gender, age_min, age_max, sort_order
		   FROM event_categories WHERE id = ? AND event_id = ?`, categoryID, eventID).
		Scan(&c.ID, &c.EventID, &c.Name, &c.Multiplier, &gender, &ageMin, &ageMax, &c.SortOrder)
	if errors.Is(err, sql.ErrNoRows) {
		return categoryDTO{}, notFound("组别不存在")
	}
	if err != nil {
		return categoryDTO{}, internal(err)
	}
	c.Gender = strPtr(gender)
	c.AgeMin = intPtr(ageMin)
	c.AgeMax = intPtr(ageMax)
	return c, nil
}

// validateCategoryAges 年龄区间可以留空，填了就必须是 0–120 且下限不大于上限。
// 整表替换的老路径不校验这两列，脏值进得去又改不动；就地更新这条路径补上。
func validateCategoryAges(ageMin, ageMax *int) error {
	for _, v := range []*int{ageMin, ageMax} {
		if v != nil && (*v < 0 || *v > 120) {
			return badRequest("组别年龄需要在 0-120 之间", v)
		}
	}
	if ageMin != nil && ageMax != nil && *ageMin > *ageMax {
		return badRequest("组别年龄下限不能大于上限", nil)
	}
	return nil
}

// multiplierRecomputeEpsilon 是「组别权重是否真的变了」的判定容差。
//
// 权重是算分公式的输入，改了就必须重算；但同一个数字经 JSON 往返一圈可能差 1e-16，
// 用 == 会把「原样提交」也当成改动、白重算一次全组积分。1e-9 远小于现场能填出的最小差
// （权重最小刻度 0.1），又远大于浮点噪声。
const multiplierRecomputeEpsilon = 1e-9

func multiplierChanged(before, after float64) bool {
	return math.Abs(before-after) > multiplierRecomputeEpsilon
}

// updateCategory 就地更新单个组别，可改 name / multiplier / gender / ageMin / ageMax / sortOrder。
//
// 与 replaceCategories 的「DELETE 全表 + INSERT」不同，这里只发一条 UPDATE：组别 id 不变，
// entries.category_id 以及它名下的成绩、流水、名次、积分全部原地保留。
// 有报名数据的小项正是靠它改名 / 改年龄 / 改性别 / 改权重 / 改排序；增删组别仍然只能走整表替换。
//
// 只有 multiplier 真的变了才在同一个事务里重算该组别的流水与名次：权重进算分公式，
// 不重算就会让已发布成绩的积分与榜单和配置静默不一致。name / gender / ageMin / ageMax /
// sortOrder 都不参与算分，改了不重算（报名、成绩、流水一个字节都不动）。
// 第二个返回值报告本次是否触发了重算，供审计留痕。
func (s *server) updateCategory(ctx context.Context, eventID, categoryID int64, in categoryDTO) (categories []categoryDTO, recomputed bool, err error) {
	name := strings.TrimSpace(in.Name)
	if name == "" {
		return nil, false, badRequest("组别 name 必填", nil)
	}
	if in.Gender != nil && *in.Gender != "" && *in.Gender != "男" && *in.Gender != "女" {
		return nil, false, badRequest("组别 gender 只能是 男 / 女", in.Gender)
	}
	if err := validateCategoryAges(in.AgeMin, in.AgeMax); err != nil {
		return nil, false, err
	}
	// 先读旧值：要不要重算全靠这次比对，拿不到旧值就无从判断。
	before, err := s.getCategory(ctx, eventID, categoryID)
	if err != nil {
		return nil, false, err
	}
	newMultiplier := multiplierOrOne(in.Multiplier)
	recompute := multiplierChanged(before.Multiplier, newMultiplier)

	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return nil, false, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	// event_id 一起进 WHERE：id 存在但挂在别的小项上时影响 0 行，按「组别不存在」处理。
	res, err := tx.ExecContext(ctx,
		`UPDATE event_categories SET name = ?, multiplier = ?, gender = ?, age_min = ?, age_max = ?, sort_order = ?
		  WHERE id = ? AND event_id = ?`,
		name, newMultiplier, nullStr(in.Gender), nullInt(in.AgeMin), nullInt(in.AgeMax),
		in.SortOrder, categoryID, eventID)
	if isUniqueViolation(err) {
		return nil, false, conflict("组别名称重复：" + name)
	}
	if err != nil {
		return nil, false, internal(err)
	}
	if err := requireChanges(res, "组别不存在"); err != nil {
		return nil, false, err
	}

	actorID := middleware.User(ctx).ID
	if recompute {
		// 与新权重保持一致：作废旧流水、按新分数重建，并把名次写回 results（榜单看的就是它）。
		score, err := recomputeLedgerTx(ctx, tx, eventID, categoryID, actorID, "组别权重变更重算")
		if err != nil {
			return nil, false, err
		}
		if err := applyComputedRanks(ctx, tx, score.Ranked); err != nil {
			return nil, false, err
		}
	}
	if err := s.bumpEvent(ctx, tx, eventID); err != nil {
		return nil, false, err
	}
	if recompute {
		if err := s.bumpStandings(ctx, tx, actorID); err != nil {
			return nil, false, err
		}
	}
	if err := tx.Commit(); err != nil {
		return nil, false, internal(err)
	}
	cats, err := s.listCategories(ctx, eventID)
	if err != nil {
		return nil, false, err
	}
	return cats, recompute, nil
}

// updateCategoryHandler 是 PUT /api/events/{id}/categories/{categoryId}：组别的就地更新。
func (s *server) updateCategoryHandler(w http.ResponseWriter, r *http.Request) (any, error) {
	eventID, err := pathID(r, "id")
	if err != nil {
		return nil, err
	}
	categoryID, err := pathID(r, "categoryId")
	if err != nil {
		return nil, err
	}
	var in categoryDTO
	if err := decodeJSON(r, &in); err != nil {
		return nil, err
	}
	before, err := s.getCategory(r.Context(), eventID, categoryID)
	if err != nil {
		return nil, err
	}
	updated, recomputed, err := s.updateCategory(r.Context(), eventID, categoryID, in)
	if err != nil {
		return nil, err
	}
	after, err := s.getCategory(r.Context(), eventID, categoryID)
	if err != nil {
		return nil, err
	}
	// 审计要能看出这次是不是还动了权重：权重变更会连带重算已发布成绩的积分与榜单，
	// 事后查「榜为什么变了」时，光看新旧权重容易漏掉这一层。
	s.audit(r.Context(), "event.category.update", "event_category", categoryID, before,
		map[string]any{"category": after, "recomputedLedger": recomputed})
	return updated, nil
}

// ---------- score channels ----------

func (s *server) listChannels(ctx context.Context, eventID int64) ([]channelDTO, error) {
	rows, err := s.ev.QueryContext(ctx,
		`SELECT id, event_id, scope, basis, profile_id, sort_order, count_to_team
		   FROM event_score_channels WHERE event_id = ? ORDER BY sort_order, id`, eventID)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]channelDTO, 0)
	for rows.Next() {
		var (
			c           channelDTO
			countToTeam int
		)
		if err := rows.Scan(&c.ID, &c.EventID, &c.Scope, &c.Basis, &c.ProfileID, &c.SortOrder, &countToTeam); err != nil {
			return nil, internal(err)
		}
		c.CountToTeam = boolPtr(countToTeam != 0)
		out = append(out, c)
	}
	return out, rows.Err()
}

// channelCountsToTeam 读请求体里的通道开关：缺省（null）按 true 处理，
// 保证不带该字段的旧客户端保存通道时不会把单位总分关掉。
func channelCountsToTeam(c channelDTO) bool {
	return c.CountToTeam == nil || *c.CountToTeam
}

func (s *server) replaceChannels(ctx context.Context, eventID int64, in []channelDTO) ([]channelDTO, error) {
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	if _, err := tx.ExecContext(ctx, `DELETE FROM event_score_channels WHERE event_id = ?`, eventID); err != nil {
		return nil, internal(err)
	}
	for i, c := range in {
		if c.Scope != "athlete" && c.Scope != "team" {
			return nil, badRequest("通道 scope 只能是 athlete/team", i)
		}
		switch c.Basis {
		case "result", "manual", "aggregate":
		default:
			return nil, badRequest("通道 basis 非法", i)
		}
		if c.ProfileID == 0 {
			return nil, badRequest("通道 profileId 必填", i)
		}
		if _, err := tx.ExecContext(ctx,
			`INSERT INTO event_score_channels (event_id, scope, basis, profile_id, sort_order, count_to_team)
			 VALUES (?, ?, ?, ?, ?, ?)`,
			eventID, c.Scope, c.Basis, c.ProfileID, c.SortOrder, boolToInt(channelCountsToTeam(c))); err != nil {
			if isUniqueViolation(err) {
				return nil, conflict("同一 scope+basis 只能配置一个通道")
			}
			if isForeignKeyViolation(err) {
				return nil, badRequest("profileId 不存在", i)
			}
			return nil, internal(err)
		}
	}
	if err := s.bumpEvent(ctx, tx, eventID); err != nil {
		return nil, err
	}
	if err := tx.Commit(); err != nil {
		return nil, internal(err)
	}
	return s.listChannels(ctx, eventID)
}

// ---------- entries ----------

const entryColumns = `e.id, e.event_id, e.category_id, e.team_id, e.athlete_id, e.member_names,
	e.bib, e.seed, e.heat, e.status, e.remark, a.name, t.code, t.name, t.short_name, c.name`

func scanEntry(row interface{ Scan(...any) error }) (entryDTO, error) {
	var (
		e              entryDTO
		athleteID      sql.NullInt64
		memberNames    sql.NullString
		bib, seed, rem sql.NullString
		heat           sql.NullInt64
		athleteName    sql.NullString
		teamCode       sql.NullString
		teamName       sql.NullString
		shortName      sql.NullString
		categoryName   sql.NullString
	)
	if err := row.Scan(&e.ID, &e.EventID, &e.CategoryID, &e.TeamID, &athleteID, &memberNames,
		&bib, &seed, &heat, &e.Status, &rem, &athleteName, &teamCode, &teamName, &shortName, &categoryName); err != nil {
		return e, err
	}
	e.AthleteID = i64Ptr(athleteID)
	e.MemberNames = parseNames(memberNames)
	e.Bib = strPtr(bib)
	e.Seed = strPtr(seed)
	e.Heat = i64Ptr(heat)
	e.Remark = strPtr(rem)
	e.AthleteName = strPtr(athleteName)
	e.TeamCode = teamCode.String
	e.TeamName = teamName.String
	e.ShortName = strPtr(shortName)
	e.CategoryName = categoryName.String
	return e, nil
}

const entrySelect = `SELECT ` + entryColumns + `
	FROM entries e
	LEFT JOIN athletes a ON a.id = e.athlete_id
	JOIN teams t ON t.id = e.team_id
	JOIN event_categories c ON c.id = e.category_id`

func (s *server) listEntries(ctx context.Context, eventID int64) ([]entryDTO, error) {
	rows, err := s.ev.QueryContext(ctx, entrySelect+` WHERE e.event_id = ? ORDER BY c.sort_order, e.id`, eventID)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]entryDTO, 0)
	for rows.Next() {
		e, err := scanEntry(rows)
		if err != nil {
			return nil, internal(err)
		}
		out = append(out, e)
	}
	return out, rows.Err()
}

// listEntriesWithResults 返回报名项及其成绩（无成绩时 result=null）。
func (s *server) listEntriesWithResults(ctx context.Context, eventID int64) ([]entryWithResultDTO, error) {
	entries, err := s.listEntries(ctx, eventID)
	if err != nil {
		return nil, err
	}
	results, err := s.resultsByEvent(ctx, eventID)
	if err != nil {
		return nil, err
	}
	byEntry := make(map[int64]resultDTO, len(results))
	for _, r := range results {
		byEntry[r.EntryID] = r
	}

	out := make([]entryWithResultDTO, 0, len(entries))
	for _, e := range entries {
		item := entryWithResultDTO{entryDTO: e}
		if r, ok := byEntry[e.ID]; ok {
			cp := r
			item.Result = &cp
		}
		out = append(out, item)
	}
	return out, nil
}

func (s *server) getEntry(ctx context.Context, id int64) (entryDTO, error) {
	e, err := scanEntry(s.ev.QueryRowContext(ctx, entrySelect+` WHERE e.id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return entryDTO{}, notFound("报名项不存在")
	}
	if err != nil {
		return entryDTO{}, internal(err)
	}
	return e, nil
}

func (s *server) createEntry(ctx context.Context, in entryDTO) (entryDTO, error) {
	if in.EventID == 0 || in.CategoryID == 0 || in.TeamID == 0 {
		return entryDTO{}, badRequest("eventId、categoryId、teamId 必填", nil)
	}
	status, err := normalizeEntryStatus(in.Status)
	if err != nil {
		return entryDTO{}, err
	}
	if err := s.checkCategoryInEvent(ctx, in.EventID, in.CategoryID); err != nil {
		return entryDTO{}, err
	}
	res, err := s.ev.ExecContext(ctx,
		`INSERT INTO entries (event_id, category_id, team_id, athlete_id, member_names, bib, seed, heat, status, remark)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		in.EventID, in.CategoryID, in.TeamID, nullI64(in.AthleteID), marshalNames(in.MemberNames),
		nullStr(in.Bib), nullStr(in.Seed), nullI64(in.Heat), status, nullStr(in.Remark))
	if isUniqueViolation(err) {
		return entryDTO{}, conflict("该报名项已存在")
	}
	if isForeignKeyViolation(err) {
		return entryDTO{}, badRequest("eventId/categoryId/teamId/athleteId 不存在", nil)
	}
	if err != nil {
		return entryDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return entryDTO{}, internal(err)
	}
	return s.getEntry(ctx, id)
}

func (s *server) updateEntry(ctx context.Context, id int64, in entryDTO) (entryDTO, error) {
	// 先确认报名项存在：小项不可改，categoryId 要拿它的 event_id 来校验。
	// 这条查询同时守住了 404 语义，别让后面的校验把它降级成 400。
	eventID, err := s.entryEventID(ctx, id)
	if err != nil {
		return entryDTO{}, err
	}
	status, err := normalizeEntryStatus(in.Status)
	if err != nil {
		return entryDTO{}, err
	}
	if err := s.checkCategoryInEvent(ctx, eventID, in.CategoryID); err != nil {
		return entryDTO{}, err
	}
	res, err := s.ev.ExecContext(ctx,
		`UPDATE entries SET category_id = ?, team_id = ?, athlete_id = ?, member_names = ?,
		        bib = ?, seed = ?, heat = ?, status = ?, remark = ? WHERE id = ?`,
		in.CategoryID, in.TeamID, nullI64(in.AthleteID), marshalNames(in.MemberNames),
		nullStr(in.Bib), nullStr(in.Seed), nullI64(in.Heat), status, nullStr(in.Remark), id)
	if isUniqueViolation(err) {
		return entryDTO{}, conflict("该报名项已存在")
	}
	if isForeignKeyViolation(err) {
		return entryDTO{}, badRequest("categoryId/teamId/athleteId 不存在", nil)
	}
	if err != nil {
		return entryDTO{}, internal(err)
	}
	if err := requireChanges(res, "报名项不存在"); err != nil {
		return entryDTO{}, err
	}
	return s.getEntry(ctx, id)
}

// entryEventID 读报名项所属小项：小项不可改，更新组别时要以它为准做归属校验。
// 找不到时给 404，调用方（更新）原本也靠 requireChanges 给出同样的语义。
func (s *server) entryEventID(ctx context.Context, id int64) (int64, error) {
	var eventID int64
	err := s.ev.QueryRowContext(ctx, `SELECT event_id FROM entries WHERE id = ?`, id).Scan(&eventID)
	if errors.Is(err, sql.ErrNoRows) {
		return 0, notFound("报名项不存在")
	}
	if err != nil {
		return 0, internal(err)
	}
	return eventID, nil
}

// checkCategoryInEvent 拦住「A 小项的报名挂在 B 小项的组别上」。
//
// event_categories 只有 (event_id, name) 唯一约束，entries 也没有 (event_id, category_id)
// 复合外键，所以外键只能保证组别存在、保证不了同属一个小项。组别不存在时放行，
// 交给 INSERT/UPDATE 的外键报错，保持原有「...不存在」的 400 文案不变。
func (s *server) checkCategoryInEvent(ctx context.Context, eventID, categoryID int64) error {
	var catEvent int64
	err := s.ev.QueryRowContext(ctx, `SELECT event_id FROM event_categories WHERE id = ?`, categoryID).Scan(&catEvent)
	switch {
	case errors.Is(err, sql.ErrNoRows):
		return nil
	case err != nil:
		return internal(err)
	case catEvent != eventID:
		return badRequest("categoryId 不属于该小项", categoryID)
	}
	return nil
}

func (s *server) deleteEntry(ctx context.Context, id int64) error {
	// 报名项被成绩引用时不允许删除；业务数据一律软删（status=scratched）。
	res, err := s.ev.ExecContext(ctx, `UPDATE entries SET status = 'scratched' WHERE id = ?`, id)
	if err != nil {
		return internal(err)
	}
	return requireChanges(res, "报名项不存在")
}

// maxEntryHeat 是批次号上限：批次只是现场录入的编排分组，四位以上没有实际意义；
// 设上限同时挡住误填的大数（例如把成绩错填进批次号）。
const maxEntryHeat = 999

// setEntriesHeat 给一批报名项统一设置批次（heat 为 nil 表示清除批次 / 未分批）。
//
// 只改 entries.heat，不碰任何成绩与积分：批次不参与算分，排名与积分仍按「小项 + 组别」算。
// 幂等：重复提交同一个批次号结果一致。要求所有报名项属于同一个小项（跨小项批量设置是误操作）。
func (s *server) setEntriesHeat(ctx context.Context, entryIDs []int64, heat *int64) (entryHeatResultDTO, error) {
	ids := dedupeIDs(entryIDs)
	if len(ids) == 0 {
		return entryHeatResultDTO{}, badRequest("entryIds 不能为空", nil)
	}
	if heat != nil && (*heat < 1 || *heat > maxEntryHeat) {
		return entryHeatResultDTO{}, badRequest(fmt.Sprintf("heat 需要是 1-%d 的整数，或传 null 清除批次", maxEntryHeat), nil)
	}

	args := make([]any, 0, len(ids))
	for _, id := range ids {
		args = append(args, id)
	}
	rows, err := s.ev.QueryContext(ctx,
		`SELECT id, event_id FROM entries WHERE id IN (`+placeholders(len(ids))+`)`, args...)
	if err != nil {
		return entryHeatResultDTO{}, internal(err)
	}
	defer func() { _ = rows.Close() }()

	found := make(map[int64]bool, len(ids))
	events := make(map[int64]bool)
	for rows.Next() {
		var (
			entryID int64
			eventID int64
		)
		if err := rows.Scan(&entryID, &eventID); err != nil {
			return entryHeatResultDTO{}, internal(err)
		}
		found[entryID] = true
		events[eventID] = true
	}
	if err := rows.Err(); err != nil {
		return entryHeatResultDTO{}, internal(err)
	}

	missing := make([]int64, 0)
	for _, id := range ids {
		if !found[id] {
			missing = append(missing, id)
		}
	}
	if len(missing) > 0 {
		return entryHeatResultDTO{}, badRequest("部分报名项不存在", missing)
	}
	// 批次挂在「小项 + 组别」之下，批量设置跨小项一定是选错了行。
	if len(events) > 1 {
		return entryHeatResultDTO{}, badRequest("不能跨小项批量设置批次，请在同一小项内操作", nil)
	}

	res, err := s.ev.ExecContext(ctx,
		`UPDATE entries SET heat = ? WHERE id IN (`+placeholders(len(ids))+`)`,
		append([]any{nullI64(heat)}, args...)...)
	if err != nil {
		return entryHeatResultDTO{}, internal(err)
	}
	updated, err := res.RowsAffected()
	if err != nil {
		return entryHeatResultDTO{}, internal(err)
	}
	return entryHeatResultDTO{Updated: int(updated), Heat: heat, EntryIDs: ids}, nil
}