package service

import (
	"fmt"
	"sort"

	"gorm.io/gorm"
	"level_go/internal/model"
)

type LimitBoardService struct {
	DB *gorm.DB
}

type limitBoardHistoryRow struct {
	TsCode    string `gorm:"column:ts_code"`
	TradeDate string `gorm:"column:trade_date"`
}

func boardLabel(boardCount int) string {
	switch boardCount {
	case 1:
		return "首板"
	case 2:
		return "二板"
	case 3:
		return "三板"
	case 4:
		return "四板"
	case 5:
		return "五板"
	case 6:
		return "六板"
	case 7:
		return "七板"
	case 8:
		return "八板"
	case 9:
		return "九板"
	default:
		return fmt.Sprintf("%d板", boardCount)
	}
}

func (s *LimitBoardService) GetLimitBoardOverview(tradeDate string) (model.LimitBoardResponse, error) {
	resp := model.LimitBoardResponse{TradeDate: tradeDate}

	tradeDates, dateIndex, err := s.loadTradeCalendar(tradeDate)
	if err != nil {
		return resp, err
	}
	if dateIndex == -1 {
		return resp, nil
	}

	resp.RecentMaxBoardStats, err = s.buildRecentMaxBoardStats(tradeDates, dateIndex)
	if err != nil {
		return resp, err
	}

	limitStocks, err := s.loadCurrentLimitStocks(tradeDate)
	if err != nil {
		return resp, err
	}
	if len(limitStocks) == 0 {
		return resp, nil
	}

	historyMap, err := s.loadLimitHistory(limitStocks, tradeDate)
	if err != nil {
		return resp, err
	}

	groupMap, maxBoardCount := buildLimitBoardGroups(limitStocks, tradeDates, dateIndex, historyMap)
	resp.Groups = sortLimitBoardGroups(groupMap)
	resp.Summary = model.LimitBoardSummary{
		MaxBoardCount: maxBoardCount,
		LimitCount:    len(limitStocks),
		GroupCount:    len(resp.Groups),
	}

	return resp, nil
}

func (s *LimitBoardService) buildRecentMaxBoardStats(tradeDates []string, dateIndex int) ([]model.LimitBoardDailyMax, error) {
	startIndex := 0
	if dateIndex >= 29 {
		startIndex = dateIndex - 29
	}
	windowDates := tradeDates[startIndex : dateIndex+1]
	if len(windowDates) == 0 {
		return []model.LimitBoardDailyMax{}, nil
	}

	var history []limitBoardHistoryRow
	if err := s.DB.Table("stock_limit_data").
		Select("ts_code, DATE_FORMAT(trade_date, '%Y-%m-%d') AS trade_date").
		Where("trade_date BETWEEN ? AND ? AND status = ?", windowDates[0], windowDates[len(windowDates)-1], 1).
		Order("ts_code ASC, trade_date ASC").
		Scan(&history).Error; err != nil {
		return nil, err
	}

	dateByCode := make(map[string]map[string]struct{})
	for _, item := range history {
		if _, ok := dateByCode[item.TsCode]; !ok {
			dateByCode[item.TsCode] = make(map[string]struct{})
		}
		dateByCode[item.TsCode][item.TradeDate] = struct{}{}
	}

	maxBoardByDate := make(map[string]int, len(windowDates))
	for _, tradeDate := range windowDates {
		maxBoardByDate[tradeDate] = 0
	}

	for _, limitDates := range dateByCode {
		for idx, tradeDate := range windowDates {
			if _, ok := limitDates[tradeDate]; !ok {
				continue
			}

			boardCount := 0
			for j := idx; j >= 0; j-- {
				if _, ok := limitDates[windowDates[j]]; !ok {
					break
				}
				boardCount++
			}

			if boardCount > maxBoardByDate[tradeDate] {
				maxBoardByDate[tradeDate] = boardCount
			}
		}
	}

	stats := make([]model.LimitBoardDailyMax, 0, len(windowDates))
	for _, tradeDate := range windowDates {
		stats = append(stats, model.LimitBoardDailyMax{
			TradeDate:     tradeDate,
			MaxBoardCount: maxBoardByDate[tradeDate],
		})
	}

	return stats, nil
}

func (s *LimitBoardService) loadTradeCalendar(tradeDate string) ([]string, int, error) {
	var tradeDates []string
	if err := s.DB.Table("trade_calendar").
		Select("DATE_FORMAT(cal_date, '%Y-%m-%d') AS trade_date").
		Where("exchange = ? AND is_open = ? AND cal_date <= ?", "SSE", 1, tradeDate).
		Order("cal_date ASC").
		Scan(&tradeDates).Error; err != nil {
		return nil, -1, err
	}

	dateIndex := -1
	for i, d := range tradeDates {
		if d == tradeDate {
			dateIndex = i
			break
		}
	}

	return tradeDates, dateIndex, nil
}

func (s *LimitBoardService) loadCurrentLimitStocks(tradeDate string) ([]model.LimitBoardStock, error) {
	var stocks []model.LimitBoardStock
	query := `SELECT
		l.symbol,
		l.ts_code,
		l.name,
		COALESCE(l.market, '') AS market,
		DATE_FORMAT(l.trade_date, '%Y-%m-%d') AS trade_date,
		COALESCE(d.close, l.close, 0) AS close,
		COALESCE(l.limit_price, 0) AS limit_price,
		COALESCE(d.pct_chg, 0) AS pct_chg
	FROM stock_limit_data l
	LEFT JOIN stock_daily d
		ON d.ts_code = l.ts_code AND d.trade_date = l.trade_date
	WHERE l.trade_date = ? AND l.status = 1
	ORDER BY d.pct_chg DESC, l.ts_code ASC`

	err := s.DB.Raw(query, tradeDate).Scan(&stocks).Error
	return stocks, err
}

func (s *LimitBoardService) loadLimitHistory(stocks []model.LimitBoardStock, tradeDate string) (map[string]map[string]struct{}, error) {
	codes := make([]string, 0, len(stocks))
	for _, stock := range stocks {
		codes = append(codes, stock.TsCode)
	}

	var history []limitBoardHistoryRow
	if err := s.DB.Table("stock_limit_data").
		Select("ts_code, DATE_FORMAT(trade_date, '%Y-%m-%d') AS trade_date").
		Where("ts_code IN ? AND trade_date <= ? AND status = ?", codes, tradeDate, 1).
		Scan(&history).Error; err != nil {
		return nil, err
	}

	historyMap := make(map[string]map[string]struct{}, len(codes))
	for _, item := range history {
		if _, ok := historyMap[item.TsCode]; !ok {
			historyMap[item.TsCode] = make(map[string]struct{})
		}
		historyMap[item.TsCode][item.TradeDate] = struct{}{}
	}

	return historyMap, nil
}

func buildLimitBoardGroups(stocks []model.LimitBoardStock, tradeDates []string, dateIndex int, historyMap map[string]map[string]struct{}) (map[int][]model.LimitBoardStock, int) {
	groupMap := make(map[int][]model.LimitBoardStock)
	maxBoardCount := 0

	for i := range stocks {
		boardCount := calcBoardCount(tradeDates, dateIndex, historyMap[stocks[i].TsCode])
		stocks[i].BoardCount = boardCount
		stocks[i].BoardLabel = boardLabel(boardCount)
		stocks[i].DisplayStatus = boardLabel(boardCount)

		if boardCount > maxBoardCount {
			maxBoardCount = boardCount
		}
		groupMap[boardCount] = append(groupMap[boardCount], stocks[i])
	}

	return groupMap, maxBoardCount
}

func calcBoardCount(tradeDates []string, dateIndex int, limitDates map[string]struct{}) int {
	boardCount := 0
	for i := dateIndex; i >= 0; i-- {
		if _, ok := limitDates[tradeDates[i]]; !ok {
			break
		}
		boardCount++
	}
	return boardCount
}

func sortLimitBoardGroups(groupMap map[int][]model.LimitBoardStock) []model.LimitBoardGroup {
	boardCounts := make([]int, 0, len(groupMap))
	for boardCount := range groupMap {
		boardCounts = append(boardCounts, boardCount)
	}
	sort.Sort(sort.Reverse(sort.IntSlice(boardCounts)))

	groups := make([]model.LimitBoardGroup, 0, len(boardCounts))
	for _, boardCount := range boardCounts {
		stocks := groupMap[boardCount]
		sort.Slice(stocks, func(i, j int) bool {
			if stocks[i].PctChg == stocks[j].PctChg {
				return stocks[i].TsCode < stocks[j].TsCode
			}
			return stocks[i].PctChg > stocks[j].PctChg
		})

		groups = append(groups, model.LimitBoardGroup{
			BoardCount: boardCount,
			Label:      boardLabel(boardCount),
			Count:      len(stocks),
			Stocks:     stocks,
		})
	}

	return groups
}