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

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

namespace Application.Features.Api.Stocks.GetIndices;

/// <summary>
/// 대표 시장지수 — 최신 거래일의 코스피/코스닥(+KRX 100)만 반환 (헤더 티커 + /market, d0 §3-D).
/// 지수명이 정확히 대표명과 일치하는 행만 취하고, 계열 순서(KOSPI→KOSDAQ→KRX)로 정렬한다.
/// </summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    // (계열, 대표 지수명) — KRX OpenAPI IDX_NM 기준
    private static readonly (MarketIndexSeries Series, string Name)[] KeyIndices =
    [
        (MarketIndexSeries.KOSPI, "코스피"),
        (MarketIndexSeries.KOSDAQ, "코스닥"),
        (MarketIndexSeries.KRX, "KRX 100")
    ];

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var latest = await db.IndexDailyPrice.AsNoTracking().OrderByDescending(c => c.TradeDate).Select(c => (DateOnly?)c.TradeDate).FirstOrDefaultAsync(ct);

        if (latest is null)
        {
            return new Response
            {
                List = []
            };
        }

        var names = KeyIndices.Select(c => c.Name).ToArray();

        var rows = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.TradeDate == latest.Value && names.Contains(c.IndexName))
            .Select(c => new Response.Row
            {
                Series = c.Series,
                Name = c.IndexName,
                Close = c.Close,
                ChangeVal = c.ChangeVal,
                FlucRateBp = c.FlucRateBp,
                TradeDate = c.TradeDate
            })
            .ToListAsync(ct);

        // 대표 지수명 순서(KOSPI→KOSDAQ→KRX)로 정렬
        var ordered = KeyIndices
            .Select(k => rows.FirstOrDefault(r => r.Series == k.Series && r.Name == k.Name))
            .Where(r => r is not null)
            .Select(r => r!)
            .ToList();

        return new Response
        {
            List = ordered
        };
    }
}