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

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;

namespace Application.Features.Api.Stocks.GetQuotes;

/// <summary>경량 배치 시세 — 코드/종가/등락률만, 최대 50개 (d0 §3-D, D1 소유). Stock denorm 만 읽어 조인 없음.</summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    public const int MaxCodes = 50;

    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var codes = request.Codes.Where(c => !string.IsNullOrWhiteSpace(c)).Select(c => c.Trim()).Distinct().ToList();

        if (codes.Count == 0)
        {
            return new Response
            {
                List = []
            };
        }

        if (codes.Count > MaxCodes)
        {
            return Result.Failure<Response>(Error.Problem("Stock.TooManyCodes", $"코드는 최대 {MaxCodes}개까지 조회할 수 있습니다."));
        }

        var list = await db.Stock.AsNoTracking()
            .Where(c => codes.Contains(c.Code))
            .Select(c => new Response.Row
            {
                Code = c.Code,
                ClosePrice = c.LastClosePrice,
                ChangeRate = c.LastChangeRate
            })
            .ToListAsync(ct);

        return new Response
        {
            List = list
        };
    }
}