package httpapi

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"

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

// 本文件是赛事库（event.db）的读写层。store 包只负责连接与迁移，
// 仓储查询按实体分文件放在 httpapi 内，避免改动 store 的公开签名。

func strPtr(ns sql.NullString) *string {
	if !ns.Valid {
		return nil
	}
	v := ns.String
	return &v
}

func i64Ptr(ni sql.NullInt64) *int64 {
	if !ni.Valid {
		return nil
	}
	v := ni.Int64
	return &v
}

func intPtr(ni sql.NullInt64) *int {
	if !ni.Valid {
		return nil
	}
	v := int(ni.Int64)
	return &v
}

func f64Ptr(nf sql.NullFloat64) *float64 {
	if !nf.Valid {
		return nil
	}
	v := nf.Float64
	return &v
}

func nullStr(p *string) any {
	if p == nil || *p == "" {
		return nil
	}
	return *p
}

func nullI64(p *int64) any {
	if p == nil {
		return nil
	}
	return *p
}

func nullInt(p *int) any {
	if p == nil {
		return nil
	}
	return *p
}

func nullF64(p *float64) any {
	if p == nil {
		return nil
	}
	return *p
}

func lastInsertID(res sql.Result) (int64, error) {
	id, err := res.LastInsertId()
	if err != nil {
		return 0, fmt.Errorf("获取自增 id: %w", err)
	}
	return id, nil
}

// requireChanges 把「影响行数为 0」翻译成 404。
func requireChanges(res sql.Result, message string) error {
	n, err := res.RowsAffected()
	if err != nil {
		return internal(err)
	}
	if n == 0 {
		return notFound(message)
	}
	return nil
}

func isUniqueViolation(err error) bool {
	if err == nil {
		return false
	}
	msg := strings.ToLower(err.Error())
	return strings.Contains(msg, "unique") || strings.Contains(msg, "constraint failed")
}

func isForeignKeyViolation(err error) bool {
	if err == nil {
		return false
	}
	return strings.Contains(strings.ToLower(err.Error()), "foreign key")
}

func exists(ctx context.Context, db *sql.DB, query string, args ...any) (bool, error) {
	var one int
	err := db.QueryRowContext(ctx, query, args...).Scan(&one)
	switch {
	case errors.Is(err, sql.ErrNoRows):
		return false, nil
	case err != nil:
		return false, err
	}
	return true, nil
}

// ---------- teams ----------

const teamColumns = `id, code, name, short_name, logo_path, color, sort_order, active`

func scanTeam(row interface{ Scan(...any) error }) (teamDTO, error) {
	var (
		t                          teamDTO
		shortName, logoPath, color sql.NullString
	)
	err := row.Scan(&t.ID, &t.Code, &t.Name, &shortName, &logoPath, &color, &t.SortOrder, &t.Active)
	t.ShortName = strPtr(shortName)
	t.LogoPath = strPtr(logoPath)
	t.Color = strPtr(color)
	return t, err
}

func (s *server) listTeams(ctx context.Context) ([]teamDTO, error) {
	rows, err := s.ev.QueryContext(ctx, `SELECT `+teamColumns+` FROM teams ORDER BY sort_order, code`)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

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

func (s *server) teamMap(ctx context.Context) (map[int64]teamDTO, error) {
	return teamMapQ(ctx, s.ev)
}

// teamMapQ 与 teamMap 同义，但可在事务内使用，保证榜单快照与写操作看到同一状态。
func teamMapQ(ctx context.Context, q queryer) (map[int64]teamDTO, error) {
	rows, err := q.QueryContext(ctx, `SELECT `+teamColumns+` FROM teams ORDER BY sort_order, code`)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make(map[int64]teamDTO)
	for rows.Next() {
		t, err := scanTeam(rows)
		if err != nil {
			return nil, internal(err)
		}
		out[t.ID] = t
	}
	return out, rows.Err()
}

func (s *server) getTeam(ctx context.Context, id int64) (teamDTO, error) {
	return teamByIDQ(ctx, s.ev, id)
}

// teamByIDQ 在给定连接/事务内读取单位，供写事务内构造 change_log 载荷复用。
func teamByIDQ(ctx context.Context, q queryer, id int64) (teamDTO, error) {
	t, err := scanTeam(q.QueryRowContext(ctx, `SELECT `+teamColumns+` FROM teams WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return teamDTO{}, notFound("单位不存在")
	}
	if err != nil {
		return teamDTO{}, internal(err)
	}
	return t, nil
}

func (s *server) createTeam(ctx context.Context, in teamDTO) (teamDTO, error) {
	if strings.TrimSpace(in.Code) == "" || strings.TrimSpace(in.Name) == "" {
		return teamDTO{}, badRequest("code 与 name 必填", nil)
	}
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return teamDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`INSERT INTO teams (code, name, short_name, logo_path, color, sort_order, active)
		 VALUES (?, ?, ?, ?, ?, ?, ?)`,
		in.Code, in.Name, nullStr(in.ShortName), nullStr(in.LogoPath), nullStr(in.Color), in.SortOrder, in.Active)
	if isUniqueViolation(err) {
		return teamDTO{}, conflict("单位编码已存在")
	}
	if err != nil {
		return teamDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return teamDTO{}, internal(err)
	}
	team, err := teamByIDQ(ctx, tx, id)
	if err != nil {
		return teamDTO{}, err
	}
	// 单位改名/新建要推给大屏，否则榜单里的单位名不会刷新。
	if err := bumpVersion(ctx, tx, "teams", id, "upsert", team, middleware.User(ctx).ID); err != nil {
		return teamDTO{}, err
	}
	if err := tx.Commit(); err != nil {
		return teamDTO{}, internal(err)
	}
	return team, nil
}

func (s *server) updateTeam(ctx context.Context, id int64, in teamDTO) (teamDTO, error) {
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return teamDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`UPDATE teams SET code = ?, name = ?, short_name = ?, logo_path = ?, color = ?, sort_order = ?, active = ?
		  WHERE id = ?`,
		in.Code, in.Name, nullStr(in.ShortName), nullStr(in.LogoPath), nullStr(in.Color), in.SortOrder, in.Active, id)
	if isUniqueViolation(err) {
		return teamDTO{}, conflict("单位编码已存在")
	}
	if err != nil {
		return teamDTO{}, internal(err)
	}
	if err := requireChanges(res, "单位不存在"); err != nil {
		return teamDTO{}, err
	}
	team, err := teamByIDQ(ctx, tx, id)
	if err != nil {
		return teamDTO{}, err
	}
	if err := bumpVersion(ctx, tx, "teams", id, "upsert", team, middleware.User(ctx).ID); err != nil {
		return teamDTO{}, err
	}
	if err := tx.Commit(); err != nil {
		return teamDTO{}, internal(err)
	}
	return team, nil
}

func (s *server) deleteTeam(ctx context.Context, id int64) error {
	// 业务数据软删除：置 active=0，保留历史成绩与流水。
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx, `UPDATE teams SET active = 0 WHERE id = ?`, id)
	if err != nil {
		return internal(err)
	}
	if err := requireChanges(res, "单位不存在"); err != nil {
		return err
	}
	if err := bumpVersion(ctx, tx, "teams", id, "void", map[string]any{"id": id}, middleware.User(ctx).ID); err != nil {
		return err
	}
	return tx.Commit()
}

// ---------- athletes ----------

const athleteColumns = `id, name, gender, team_id, employee_no, active`

func scanAthlete(row interface{ Scan(...any) error }) (athleteDTO, error) {
	var (
		a             athleteDTO
		gender, empNo sql.NullString
		teamID        sql.NullInt64
	)
	err := row.Scan(&a.ID, &a.Name, &gender, &teamID, &empNo, &a.Active)
	a.Gender = strPtr(gender)
	a.EmployeeNo = strPtr(empNo)
	if teamID.Valid {
		a.TeamID = teamID.Int64
	}
	return a, err
}

func (s *server) listAthletes(ctx context.Context, teamID int64) ([]athleteDTO, error) {
	query := `SELECT ` + athleteColumns + ` FROM athletes`
	args := []any{}
	if teamID > 0 {
		query += ` WHERE team_id = ?`
		args = append(args, teamID)
	}
	query += ` ORDER BY name`

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

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

func (s *server) getAthlete(ctx context.Context, id int64) (athleteDTO, error) {
	a, err := scanAthlete(s.ev.QueryRowContext(ctx, `SELECT `+athleteColumns+` FROM athletes WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return athleteDTO{}, notFound("运动员不存在")
	}
	if err != nil {
		return athleteDTO{}, internal(err)
	}
	return a, nil
}

func (s *server) createAthlete(ctx context.Context, in athleteDTO) (athleteDTO, error) {
	if strings.TrimSpace(in.Name) == "" || in.TeamID == 0 {
		return athleteDTO{}, badRequest("name 与 teamId 必填", nil)
	}
	res, err := s.ev.ExecContext(ctx,
		`INSERT INTO athletes (name, gender, team_id, employee_no, active) VALUES (?, ?, ?, ?, ?)`,
		in.Name, nullStr(in.Gender), in.TeamID, nullStr(in.EmployeeNo), in.Active)
	if isForeignKeyViolation(err) {
		return athleteDTO{}, badRequest("teamId 不存在", nil)
	}
	if err != nil {
		return athleteDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return athleteDTO{}, internal(err)
	}
	return s.getAthlete(ctx, id)
}

func (s *server) updateAthlete(ctx context.Context, id int64, in athleteDTO) (athleteDTO, error) {
	res, err := s.ev.ExecContext(ctx,
		`UPDATE athletes SET name = ?, gender = ?, team_id = ?, employee_no = ?, active = ? WHERE id = ?`,
		in.Name, nullStr(in.Gender), in.TeamID, nullStr(in.EmployeeNo), in.Active, id)
	if isForeignKeyViolation(err) {
		return athleteDTO{}, badRequest("teamId 不存在", nil)
	}
	if err != nil {
		return athleteDTO{}, internal(err)
	}
	if err := requireChanges(res, "运动员不存在"); err != nil {
		return athleteDTO{}, err
	}
	return s.getAthlete(ctx, id)
}

func (s *server) deleteAthlete(ctx context.Context, id int64) error {
	res, err := s.ev.ExecContext(ctx, `UPDATE athletes SET active = 0 WHERE id = ?`, id)
	if err != nil {
		return internal(err)
	}
	return requireChanges(res, "运动员不存在")
}

// ---------- sports ----------

const sportColumns = `id, code, name, short_name, default_profile_id, sort_order, active`

func scanSport(row interface{ Scan(...any) error }) (sportDTO, error) {
	var (
		sp               sportDTO
		shortName        sql.NullString
		defaultProfileID sql.NullInt64
	)
	err := row.Scan(&sp.ID, &sp.Code, &sp.Name, &shortName, &defaultProfileID, &sp.SortOrder, &sp.Active)
	sp.ShortName = strPtr(shortName)
	sp.DefaultProfileID = i64Ptr(defaultProfileID)
	return sp, err
}

func (s *server) listSports(ctx context.Context) ([]sportDTO, error) {
	rows, err := s.ev.QueryContext(ctx, `SELECT `+sportColumns+` FROM sports ORDER BY sort_order, code`)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

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

func (s *server) getSport(ctx context.Context, id int64) (sportDTO, error) {
	sp, err := scanSport(s.ev.QueryRowContext(ctx, `SELECT `+sportColumns+` FROM sports WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return sportDTO{}, notFound("大项不存在")
	}
	if err != nil {
		return sportDTO{}, internal(err)
	}
	return sp, nil
}

func (s *server) createSport(ctx context.Context, in sportDTO) (sportDTO, error) {
	if strings.TrimSpace(in.Code) == "" || strings.TrimSpace(in.Name) == "" {
		return sportDTO{}, badRequest("code 与 name 必填", nil)
	}
	res, err := s.ev.ExecContext(ctx,
		`INSERT INTO sports (code, name, short_name, default_profile_id, sort_order, active)
		 VALUES (?, ?, ?, ?, ?, ?)`,
		in.Code, in.Name, nullStr(in.ShortName), nullI64(in.DefaultProfileID), in.SortOrder, in.Active)
	if isUniqueViolation(err) {
		return sportDTO{}, conflict("大项编码已存在")
	}
	if err != nil {
		return sportDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return sportDTO{}, internal(err)
	}
	return s.getSport(ctx, id)
}

func (s *server) updateSport(ctx context.Context, id int64, in sportDTO) (sportDTO, error) {
	res, err := s.ev.ExecContext(ctx,
		`UPDATE sports SET code = ?, name = ?, short_name = ?, default_profile_id = ?, sort_order = ?, active = ?
		  WHERE id = ?`,
		in.Code, in.Name, nullStr(in.ShortName), nullI64(in.DefaultProfileID), in.SortOrder, in.Active, id)
	if isUniqueViolation(err) {
		return sportDTO{}, conflict("大项编码已存在")
	}
	if err != nil {
		return sportDTO{}, internal(err)
	}
	if err := requireChanges(res, "大项不存在"); err != nil {
		return sportDTO{}, err
	}
	return s.getSport(ctx, id)
}

func (s *server) deleteSport(ctx context.Context, id int64) error {
	// 大项有子项目时不允许软删，避免项目挂在不可见的大项下。
	has, err := exists(ctx, s.ev, `SELECT 1 FROM events WHERE sport_id = ? LIMIT 1`, id)
	if err != nil {
		return internal(err)
	}
	if has {
		return conflict("大项下仍有小项，不能删除")
	}
	res, err := s.ev.ExecContext(ctx, `UPDATE sports SET active = 0 WHERE id = ?`, id)
	if err != nil {
		return internal(err)
	}
	return requireChanges(res, "大项不存在")
}

// ---------- scoring profiles ----------

func (s *server) listProfiles(ctx context.Context) ([]profileDTO, error) {
	rows, err := s.ev.QueryContext(ctx,
		`SELECT id, code, name, tie_mode, record_bonus_mode, award_ranks, last_place_zero
		   FROM scoring_profiles ORDER BY code`)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]profileDTO, 0)
	for rows.Next() {
		var p profileDTO
		if err := rows.Scan(&p.ID, &p.Code, &p.Name, &p.TieMode, &p.RecordBonusMode, &p.AwardRanks, &p.LastPlaceZero); err != nil {
			return nil, internal(err)
		}
		out = append(out, p)
	}
	if err := rows.Err(); err != nil {
		return nil, internal(err)
	}
	for i := range out {
		rules, err := s.profileRules(ctx, out[i].ID)
		if err != nil {
			return nil, err
		}
		out[i].Rules = rules
	}
	return out, nil
}

func (s *server) profileRules(ctx context.Context, profileID int64) ([]profileRuleDTO, error) {
	rows, err := s.ev.QueryContext(ctx,
		`SELECT rank, points FROM scoring_profile_rules WHERE profile_id = ? ORDER BY rank`, profileID)
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = rows.Close() }()

	out := make([]profileRuleDTO, 0)
	for rows.Next() {
		var r profileRuleDTO
		if err := rows.Scan(&r.Rank, &r.Points); err != nil {
			return nil, internal(err)
		}
		out = append(out, r)
	}
	return out, rows.Err()
}

func (s *server) getProfile(ctx context.Context, id int64) (profileDTO, error) {
	var p profileDTO
	err := s.ev.QueryRowContext(ctx,
		`SELECT id, code, name, tie_mode, record_bonus_mode, award_ranks, last_place_zero
		   FROM scoring_profiles WHERE id = ?`, id).
		Scan(&p.ID, &p.Code, &p.Name, &p.TieMode, &p.RecordBonusMode, &p.AwardRanks, &p.LastPlaceZero)
	if errors.Is(err, sql.ErrNoRows) {
		return profileDTO{}, notFound("积分模板不存在")
	}
	if err != nil {
		return profileDTO{}, internal(err)
	}
	rules, err := s.profileRules(ctx, p.ID)
	if err != nil {
		return profileDTO{}, err
	}
	p.Rules = rules
	return p, nil
}

func (s *server) createProfile(ctx context.Context, in profileDTO) (profileDTO, error) {
	if strings.TrimSpace(in.Code) == "" || strings.TrimSpace(in.Name) == "" {
		return profileDTO{}, badRequest("code 与 name 必填", nil)
	}
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return profileDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`INSERT INTO scoring_profiles (code, name, tie_mode, record_bonus_mode, award_ranks, last_place_zero)
		 VALUES (?, ?, ?, ?, ?, ?)`,
		in.Code, in.Name, orDefault(in.TieMode, "skip"), orDefault(in.RecordBonusMode, "max"), in.AwardRanks, in.LastPlaceZero)
	if isUniqueViolation(err) {
		return profileDTO{}, conflict("积分模板编码已存在")
	}
	if err != nil {
		return profileDTO{}, internal(err)
	}
	id, err := lastInsertID(res)
	if err != nil {
		return profileDTO{}, internal(err)
	}
	if err := replaceProfileRules(ctx, tx, id, in.Rules); err != nil {
		return profileDTO{}, err
	}
	if err := tx.Commit(); err != nil {
		return profileDTO{}, internal(err)
	}
	return s.getProfile(ctx, id)
}

func (s *server) updateProfile(ctx context.Context, id int64, in profileDTO) (profileDTO, error) {
	tx, err := s.ev.BeginTx(ctx, nil)
	if err != nil {
		return profileDTO{}, internal(err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`UPDATE scoring_profiles SET code = ?, name = ?, tie_mode = ?, record_bonus_mode = ?,
		        award_ranks = ?, last_place_zero = ?, updated_at = datetime('now')
		  WHERE id = ?`,
		in.Code, in.Name, orDefault(in.TieMode, "skip"), orDefault(in.RecordBonusMode, "max"), in.AwardRanks, in.LastPlaceZero, id)
	if isUniqueViolation(err) {
		return profileDTO{}, conflict("积分模板编码已存在")
	}
	if err != nil {
		return profileDTO{}, internal(err)
	}
	if err := requireChanges(res, "积分模板不存在"); err != nil {
		return profileDTO{}, err
	}
	if in.Rules != nil {
		if err := replaceProfileRules(ctx, tx, id, in.Rules); err != nil {
			return profileDTO{}, err
		}
	}
	if err := tx.Commit(); err != nil {
		return profileDTO{}, internal(err)
	}
	return s.getProfile(ctx, id)
}

func replaceProfileRules(ctx context.Context, tx *sql.Tx, profileID int64, rules []profileRuleDTO) error {
	if _, err := tx.ExecContext(ctx, `DELETE FROM scoring_profile_rules WHERE profile_id = ?`, profileID); err != nil {
		return internal(err)
	}
	for _, r := range rules {
		if r.Rank < 1 {
			return badRequest("积分名次必须 >= 1", r)
		}
		if _, err := tx.ExecContext(ctx,
			`INSERT INTO scoring_profile_rules (profile_id, rank, points) VALUES (?, ?, ?)`,
			profileID, r.Rank, r.Points); err != nil {
			return internal(err)
		}
	}
	return nil
}

func orDefault(v, def string) string {
	if strings.TrimSpace(v) == "" {
		return def
	}
	return v
}