ANTOOZA-BACKEND/Application/Features/Api/Stocks/GetDomesticSummary/Handler.cs

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Domain.Entities.Stocks.ValueObject;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Api.Stocks.GetDomesticSummary;

/// <summary>
/// 국내 증시 요약 — 최신 거래일의 코스피·코스닥·KOSPI200 지수(IndexDailyPrice) + 시장별 등락종목수(StockDailyPrice×Stock).
/// 상한/하한은 가격제한 플래그가 없어 등락률 ±29.5% 근사. (투자자별 순매수·베이시스는 미지원으로 응답에서 제외)
/// </summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    private const decimal LimitThreshold = 29.5m; // 가격제한(±30%) 근사

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var rows = new List<Response.Row>();

        // ── 지수 (최신 거래일) ──
        var latestIndexDate = await db.IndexDailyPrice.AsNoTracking()
            .OrderByDescending(c => c.TradeDate)
            .Select(c => (DateOnly?)c.TradeDate)
            .FirstOrDefaultAsync(ct);

        if (latestIndexDate is not DateOnly indexDate)
        {
            return new Response { List = rows };
        }

        // 시장별 등락종목수 (최신 종목 거래일 — 지수일과 다를 수 있어 별도 산출)
        var stockDate = await db.StockDailyPrice.AsNoTracking()
            .OrderByDescending(c => c.TradingDate)
            .Select(c => (DateOnly?)c.TradingDate)
            .FirstOrDefaultAsync(ct);

        var breadthByMarket = new Dictionary<StockMarket, BreadthRow>();

        if (stockDate is DateOnly sd)
        {
            // 익명 타입으로 집계(EF GroupBy 변환 안전) 후 메모리에서 매핑
            var breadth = await db.StockDailyPrice.AsNoTracking()
                .Where(c => c.TradingDate == sd)
                .Join(db.Stock.AsNoTracking().Where(s => s.IsActive), p => p.StockID, s => s.ID, (p, s) => new { s.Market, p.ChangeRate })
                .GroupBy(x => x.Market)
                .Select(g => new
                {
                    Market = g.Key,
                    Advances = g.Count(x => x.ChangeRate > 0m),
                    Declines = g.Count(x => x.ChangeRate < 0m),
                    Unchanged = g.Count(x => x.ChangeRate == 0m),
                    LimitUp = g.Count(x => x.ChangeRate >= LimitThreshold),
                    LimitDown = g.Count(x => x.ChangeRate <= -LimitThreshold)
                })
                .ToListAsync(ct);

            breadthByMarket = breadth.ToDictionary(
                b => b.Market,
                b => new BreadthRow
                {
                    Market = b.Market,
                    Advances = b.Advances,
                    Declines = b.Declines,
                    Unchanged = b.Unchanged,
                    LimitUp = b.LimitUp,
                    LimitDown = b.LimitDown
                });
        }

        // 코스피
        await AddIndexAsync(rows, "kospi", MarketIndexSeries.KOSPI, "코스피", indexDate, breadthByMarket, StockMarket.KOSPI, ct);
        // 코스닥
        await AddIndexAsync(rows, "kosdaq", MarketIndexSeries.KOSDAQ, "코스닥", indexDate, breadthByMarket, StockMarket.KOSDAQ, ct);
        // KOSPI200 (KOSPI 계열 내 "200" 포함 지수) — 등락종목수 없음, 베이시스는 Phase 2
        await AddKospi200Async(rows, indexDate, ct);

        return new Response { List = rows };
    }

    private async Task AddIndexAsync(
        List<Response.Row> rows,
        string key,
        MarketIndexSeries series,
        string indexName,
        DateOnly indexDate,
        Dictionary<StockMarket, BreadthRow> breadthByMarket,
        StockMarket market,
        CancellationToken ct
    ) {
        var idx = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.TradeDate == indexDate && c.Series == series && c.IndexName == indexName)
            .Select(c => new { c.Close, c.ChangeVal, c.FlucRateBp })
            .FirstOrDefaultAsync(ct);

        if (idx is null)
        {
            return;
        }

        breadthByMarket.TryGetValue(market, out var b);

        rows.Add(new Response.Row
        {
            Key = key,
            Name = indexName,
            Close = idx.Close,
            ChangeVal = idx.ChangeVal,
            FlucRateBp = idx.FlucRateBp,
            TradeDate = indexDate.ToString("yyyy-MM-dd"),
            Advances = b?.Advances,
            Declines = b?.Declines,
            Unchanged = b?.Unchanged,
            LimitUp = b?.LimitUp,
            LimitDown = b?.LimitDown
        });
    }

    private async Task AddKospi200Async(List<Response.Row> rows, DateOnly indexDate, CancellationToken ct)
    {
        var idx = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.TradeDate == indexDate && c.Series == MarketIndexSeries.KOSPI && c.IndexName.Contains("200"))
            .OrderBy(c => c.IndexName)
            .Select(c => new { c.IndexName, c.Close, c.ChangeVal, c.FlucRateBp })
            .FirstOrDefaultAsync(ct);

        if (idx is null)
        {
            return;
        }

        rows.Add(new Response.Row
        {
            Key = "kospi200",
            Name = idx.IndexName,
            Close = idx.Close,
            ChangeVal = idx.ChangeVal,
            FlucRateBp = idx.FlucRateBp,
            TradeDate = indexDate.ToString("yyyy-MM-dd")
        });
    }

    private sealed class BreadthRow
    {
        public StockMarket Market { get; init; }
        public int Advances { get; init; }
        public int Declines { get; init; }
        public int Unchanged { get; init; }
        public int LimitUp { get; init; }
        public int LimitDown { get; init; }
    }
}