package realtime

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"sort"
	"strconv"
	"strings"

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

// latestResultsLimit 控制快照里「最新成绩」的行数上限，避免大屏首包过大。
// 行会按「小项 + 组别」聚合后再下发，因此组数只会比这个值更少。
const latestResultsLimit = 20

// Snapshot 是 snapshot 事件的 data，也是客户端冷启动的完整状态。
// 字段名与协议第 3 节一致；settings/standings/latestResults 的形状必须与 REST 同构，
// 否则大屏收到首包就会按错误的键名渲染。
type Snapshot struct {
	Version       int64                  `json:"version"`
	Settings      dto.EventSettings      `json:"settings"`
	Teams         []domain.Team          `json:"teams"`
	Events        []domain.Event         `json:"events"`
	Standings     []dto.StandingRow      `json:"standings"`
	Records       []Record               `json:"records"`
	LatestResults []dto.EventResultGroup `json:"latestResults"`
}

// Record 是纪录榜的一行。
type Record struct {
	ID           int64    `json:"id"`
	EventID      int64    `json:"eventId"`
	Level        string   `json:"level"`
	ResultValue  *float64 `json:"resultValue,omitempty"`
	ResultText   string   `json:"resultText,omitempty"`
	HolderName   string   `json:"holderName,omitempty"`
	HolderTeamID int64    `json:"holderTeamId,omitempty"`
	AchievedAt   string   `json:"achievedAt,omitempty"`
	IsCurrent    bool     `json:"isCurrent"`
	Source       string   `json:"source"`
}

// Snapshot 读取一份一致的完整状态。
//
// 全部查询放在同一个只读事务里，且版本号取自同一事务，
// 否则快照里的数据与版本号会错位，重连补齐时就会漏变更。
func (h *Hub) Snapshot(ctx context.Context) (*Snapshot, error) {
	if h.db == nil {
		return nil, fmt.Errorf("实时中心未绑定赛事库")
	}

	tx, err := h.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("开启快照事务: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	snap := &Snapshot{
		Teams:         []domain.Team{},
		Events:        []domain.Event{},
		Standings:     []dto.StandingRow{},
		Records:       []Record{},
		LatestResults: []dto.EventResultGroup{},
	}

	if err := tx.QueryRowContext(ctx, `SELECT COALESCE(MAX(id), 0) FROM change_log`).Scan(&snap.Version); err != nil {
		return nil, fmt.Errorf("读取快照版本号: %w", err)
	}
	values, err := loadSettings(ctx, tx)
	if err != nil {
		return nil, err
	}
	if err := fillSettings(ctx, tx, values, snap); err != nil {
		return nil, err
	}
	if err := loadTeams(ctx, tx, snap); err != nil {
		return nil, err
	}
	if err := loadEvents(ctx, tx, snap); err != nil {
		return nil, err
	}
	if err := loadStandings(ctx, tx, snap, values); err != nil {
		return nil, err
	}
	if err := loadRecords(ctx, tx, snap); err != nil {
		return nil, err
	}
	if err := loadLatestResults(ctx, tx, snap); err != nil {
		return nil, err
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("提交快照事务: %w", err)
	}
	return snap, nil
}

// loadSettings 原样读出 settings 表的键值：榜单口径要用原始字符串，
// 而线上结构需要聚合后的嵌套对象，两者由调用方分别消费。
func loadSettings(ctx context.Context, tx *sql.Tx) (map[string]string, error) {
	rows, err := tx.QueryContext(ctx, `SELECT key, value FROM settings`)
	if err != nil {
		return nil, fmt.Errorf("读取赛事配置: %w", err)
	}
	defer func() { _ = rows.Close() }()

	out := make(map[string]string)
	for rows.Next() {
		var key, value string
		if err := rows.Scan(&key, &value); err != nil {
			return nil, fmt.Errorf("解析赛事配置: %w", err)
		}
		out[key] = value
	}
	return out, rows.Err()
}

// fillSettings 聚合成与 REST /api/settings 相同的嵌套结构。
// defaultProfileId 在 settings 表里存的是模板 code，需要反查一次主键。
func fillSettings(ctx context.Context, tx *sql.Tx, values map[string]string, snap *Snapshot) error {
	snap.Settings = dto.ParseEventSettings(values)

	code := values["scoring.default_profile"]
	if code == "" {
		return nil
	}
	var id int64
	err := tx.QueryRowContext(ctx, `SELECT id FROM scoring_profiles WHERE code = ?`, code).Scan(&id)
	switch {
	case errors.Is(err, sql.ErrNoRows):
		// 配置引用的模板已被删除：保持 null，与 REST 一致，由管理端提示重选。
	case err != nil:
		return fmt.Errorf("解析默认积分模板: %w", err)
	default:
		snap.Settings.DefaultProfileID = &id
	}
	return nil
}

func loadTeams(ctx context.Context, tx *sql.Tx, snap *Snapshot) error {
	rows, err := tx.QueryContext(ctx, `
		SELECT id, code, name, COALESCE(short_name, ''), COALESCE(logo_path, ''),
		       COALESCE(color, ''), sort_order, active
		FROM teams WHERE active = 1
		ORDER BY sort_order, code`)
	if err != nil {
		return fmt.Errorf("读取单位: %w", err)
	}
	defer func() { _ = rows.Close() }()

	for rows.Next() {
		var (
			t      domain.Team
			active int
		)
		if err := rows.Scan(&t.ID, &t.Code, &t.Name, &t.ShortName, &t.LogoPath, &t.Color, &t.SortOrder, &active); err != nil {
			return fmt.Errorf("解析单位: %w", err)
		}
		t.Active = active != 0
		snap.Teams = append(snap.Teams, t)
	}
	return rows.Err()
}

func loadEvents(ctx context.Context, tx *sql.Tx, snap *Snapshot) error {
	rows, err := tx.QueryContext(ctx, `
		SELECT id, sport_id, code, name, event_type, result_mode, result_type, compare,
		       record_eligible, scored, multiplier, status,
		       COALESCE(scheduled_at, ''), COALESCE(venue, ''), sort_order, COALESCE(remark, '')
		FROM events
		ORDER BY sort_order, id`)
	if err != nil {
		return fmt.Errorf("读取小项: %w", err)
	}
	defer func() { _ = rows.Close() }()

	for rows.Next() {
		var (
			e              domain.Event
			eventType      string
			resultMode     string
			resultType     string
			compare        string
			status         string
			recordEligible int
			scored         int
		)
		if err := rows.Scan(
			&e.ID, &e.SportID, &e.Code, &e.Name, &eventType, &resultMode, &resultType, &compare,
			&recordEligible, &scored, &e.Multiplier, &status,
			&e.ScheduledAt, &e.Venue, &e.SortOrder, &e.Remark,
		); err != nil {
			return fmt.Errorf("解析小项: %w", err)
		}
		e.EventType = domain.EventType(eventType)
		e.ResultMode = domain.ResultMode(resultMode)
		e.ResultType = domain.ResultType(resultType)
		e.Compare = domain.CompareMode(compare)
		e.Status = domain.EventStatus(status)
		e.RecordEligible = recordEligible != 0
		e.Scored = scored != 0
		snap.Events = append(snap.Events, e)
	}
	return rows.Err()
}

// loadStandings 复用 domain 的排名口径，且输入与 REST /api/standings 完全一致：
// 个人流水按系数折算、团体奖牌开关生效、只有配了计分通道的项目才产出名次。
func loadStandings(ctx context.Context, tx *sql.Tx, snap *Snapshot, values map[string]string) error {
	ledger, err := loadLedger(ctx, tx)
	if err != nil {
		return err
	}
	ranked, err := loadRanked(ctx, tx)
	if err != nil {
		return err
	}
	rows := domain.BuildTeamStandings(domain.StandingsInput{
		Teams:                  snap.Teams,
		Ledger:                 ledger,
		Ranked:                 ranked,
		IndividualToTeamWeight: atofDefault(values["standings.individual_to_team_weight"], 1),
		ExcludeTeamEventMedals: !boolDefault(values["standings.medal_counts_team_events"], true),
	})
	snap.Standings = dto.StandingRows(rows, snap.Teams)
	return nil
}

func loadLedger(ctx context.Context, tx *sql.Tx) ([]domain.LedgerEntry, error) {
	rows, err := tx.QueryContext(ctx, `
		SELECT id, team_id, COALESCE(athlete_id, 0), COALESCE(event_id, 0),
		       COALESCE(entry_id, 0), COALESCE(result_id, 0), source_type, source_id, points
		FROM score_ledger WHERE voided = 0 ORDER BY id`)
	if err != nil {
		return nil, fmt.Errorf("读取积分流水: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var out []domain.LedgerEntry
	for rows.Next() {
		var (
			e          domain.LedgerEntry
			sourceType string
		)
		if err := rows.Scan(&e.ID, &e.TeamID, &e.AthleteID, &e.EventID, &e.EntryID, &e.ResultID, &sourceType, &e.SourceID, &e.Points); err != nil {
			return nil, fmt.Errorf("解析积分流水: %w", err)
		}
		e.SourceType = domain.SourceType(sourceType)
		out = append(out, e)
	}
	return out, rows.Err()
}

// loadRanked 与 REST 的 buildRanked 同源：必须 join event_score_channels，
// 否则多通道项目会把一枚奖牌算成多枚，没配通道的项目也会凭空产生奖牌。
func loadRanked(ctx context.Context, tx *sql.Tx) ([]domain.RankedResult, error) {
	rows, err := tx.QueryContext(ctx, `
		SELECT r.id, r.event_id, e.category_id, r.rank, r.result_value, r.status,
		       e.id, e.team_id, e.athlete_id, COALESCE(a.name, ''), c.scope, c.id
		  FROM results r
		  JOIN entries e ON e.id = r.entry_id
		  JOIN event_score_channels c ON c.event_id = r.event_id
		  LEFT JOIN athletes a ON a.id = e.athlete_id
		 WHERE r.state = 'published' AND r.rank IS NOT NULL AND r.rank > 0 AND r.status = 'ok'
		   AND (c.scope = 'team' OR e.athlete_id IS NOT NULL)
		 ORDER BY r.id, c.sort_order, c.id`)
	if err != nil {
		return nil, fmt.Errorf("读取奖牌名次: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var out []domain.RankedResult
	for rows.Next() {
		var (
			rr        domain.RankedResult
			value     sql.NullFloat64
			athleteID sql.NullInt64
			rank      int
		)
		if err := rows.Scan(&rr.ResultID, &rr.EventID, &rr.CategoryID, &rank, &value, &rr.Status,
			&rr.EntryID, &rr.TeamID, &athleteID, &rr.AthleteName, &rr.Scope, &rr.ChannelID); err != nil {
			return nil, fmt.Errorf("解析奖牌名次: %w", err)
		}
		rr.Rank = rank
		if value.Valid {
			v := value.Float64
			rr.ResultValue = &v
		}
		rr.AthleteID = athleteID.Int64
		rr.Shares = []domain.TeamShare{{TeamID: rr.TeamID, Weight: 1}}
		out = append(out, rr)
	}
	return out, rows.Err()
}

func loadRecords(ctx context.Context, tx *sql.Tx, snap *Snapshot) error {
	rows, err := tx.QueryContext(ctx, `
		SELECT id, event_id, level, result_value, COALESCE(result_text, ''),
		       COALESCE(holder_name, ''), COALESCE(holder_team_id, 0),
		       COALESCE(achieved_at, ''), is_current, source
		FROM records WHERE is_current = 1
		ORDER BY event_id, level, id`)
	if err != nil {
		return fmt.Errorf("读取纪录榜: %w", err)
	}
	defer func() { _ = rows.Close() }()

	for rows.Next() {
		var (
			r         Record
			value     sql.NullFloat64
			isCurrent int
		)
		if err := rows.Scan(&r.ID, &r.EventID, &r.Level, &value, &r.ResultText,
			&r.HolderName, &r.HolderTeamID, &r.AchievedAt, &isCurrent, &r.Source); err != nil {
			return fmt.Errorf("解析纪录: %w", err)
		}
		if value.Valid {
			v := value.Float64
			r.ResultValue = &v
		}
		r.IsCurrent = isCurrent != 0
		snap.Records = append(snap.Records, r)
	}
	return rows.Err()
}

// loadLatestResults 取最近发布的成绩，按「小项 + 组别」聚合成组后下发。
// 前端按组渲染（TickerBar 取最新一组、EventResultsPage 取前 N 组），平铺行会让它拿到 undefined。
func loadLatestResults(ctx context.Context, tx *sql.Tx, snap *Snapshot) error {
	rows, err := tx.QueryContext(ctx, `
		SELECT r.event_id, COALESCE(ev.code, ''), COALESCE(ev.name, ''),
		       e.category_id, COALESCE(cat.name, ''),
		       COALESCE(r.verified_at, r.recorded_at, r.updated_at, r.created_at, ''),
		       r.entry_id, r.rank, e.team_id,
		       COALESCE(t.code, ''), COALESCE(t.name, ''), COALESCE(t.short_name, ''),
		       e.athlete_id, COALESCE(a.name, ''), COALESCE(e.member_names, ''),
		       COALESCE(r.result_text, ''), r.result_value, COALESCE(r.unit, ''), r.is_tie, r.status
		  FROM results r
		  JOIN entries e ON e.id = r.entry_id
		  JOIN events ev ON ev.id = r.event_id
		  LEFT JOIN event_categories cat ON cat.id = e.category_id
		  LEFT JOIN teams t ON t.id = e.team_id
		  LEFT JOIN athletes a ON a.id = e.athlete_id
		 WHERE r.state = 'published'
		 ORDER BY COALESCE(r.verified_at, r.recorded_at, r.updated_at, r.created_at) DESC, r.id DESC
		 LIMIT ?`, latestResultsLimit)
	if err != nil {
		return fmt.Errorf("读取最新成绩: %w", err)
	}
	defer func() { _ = rows.Close() }()

	type groupKey struct {
		eventID    int64
		categoryID int64
	}
	index := make(map[groupKey]int)

	for rows.Next() {
		var (
			eventID, categoryID  int64
			eventCode, eventName string
			categoryName         string
			publishedAt          string
			row                  dto.EventResultRow
			rank                 sql.NullInt64
			value                sql.NullFloat64
			athleteID            sql.NullInt64
			athleteName          string
			shortName            string
			memberNames          string
			isTie                int
		)
		if err := rows.Scan(&eventID, &eventCode, &eventName, &categoryID, &categoryName, &publishedAt,
			&row.EntryID, &rank, &row.TeamID, &row.TeamCode, &row.TeamName, &shortName,
			&athleteID, &athleteName, &memberNames,
			&row.ResultText, &value, &row.Unit, &isTie, &row.Status); err != nil {
			return fmt.Errorf("解析最新成绩: %w", err)
		}
		if rank.Valid {
			v := int(rank.Int64)
			row.Rank = &v
		}
		if value.Valid {
			v := value.Float64
			row.ResultValue = &v
		}
		if athleteID.Valid && athleteID.Int64 != 0 {
			v := athleteID.Int64
			row.AthleteID = &v
		}
		row.AthleteName = nilIfEmpty(athleteName)
		row.ShortName = nilIfEmpty(shortName)
		row.MemberNames = parseMemberNames(memberNames)
		row.IsTie = isTie != 0

		key := groupKey{eventID: eventID, categoryID: categoryID}
		i, ok := index[key]
		if !ok {
			i = len(snap.LatestResults)
			index[key] = i
			snap.LatestResults = append(snap.LatestResults, dto.EventResultGroup{
				EventID:      eventID,
				EventCode:    eventCode,
				EventName:    eventName,
				CategoryID:   categoryID,
				CategoryName: categoryName,
				PublishedAt:  nilIfEmpty(publishedAt),
				Rows:         []dto.EventResultRow{},
			})
		}
		snap.LatestResults[i].Rows = append(snap.LatestResults[i].Rows, row)
	}
	if err := rows.Err(); err != nil {
		return err
	}

	// 行按发布时间倒序取回，组内需改回名次顺序；无名次的排最后。
	for i := range snap.LatestResults {
		sort.SliceStable(snap.LatestResults[i].Rows, func(a, b int) bool {
			ra, rb := snap.LatestResults[i].Rows[a], snap.LatestResults[i].Rows[b]
			switch {
			case ra.Rank == nil && rb.Rank == nil:
				return ra.EntryID < rb.EntryID
			case ra.Rank == nil:
				return false
			case rb.Rank == nil:
				return true
			default:
				return *ra.Rank < *rb.Rank
			}
		})
	}
	return nil
}

// parseMemberNames 解析 entries.member_names；空值或坏 JSON 一律当作「无成员名单」。
func parseMemberNames(raw string) []string {
	if raw == "" {
		return nil
	}
	var out []string
	if err := json.Unmarshal([]byte(raw), &out); err != nil {
		return nil
	}
	return out
}

func nilIfEmpty(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}

func atofDefault(v string, def float64) float64 {
	n, err := strconv.ParseFloat(strings.TrimSpace(v), 64)
	if err != nil {
		return def
	}
	return n
}

func boolDefault(v string, def bool) bool {
	switch strings.ToLower(strings.TrimSpace(v)) {
	case "true", "1", "yes":
		return true
	case "false", "0", "no":
		return false
	default:
		return def
	}
}