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

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

namespace Application.Features.Api.Stocks.Suggest;

/// <summary>종목 자동완성 — 이름/코드 prefix 매칭 상위 10건 (d0 §3-D, D1 소유)</summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    private const int MaxItems = 10;

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var q = request.Q?.Trim();
        if (string.IsNullOrEmpty(q))
        {
            return new Response
            {
                List = []
            };
        }

        var list = await db.Stock.AsNoTracking()
            .Where(c => c.IsActive && (c.Name.StartsWith(q) || c.Code.StartsWith(q)))
            .OrderBy(c => c.Name).ThenBy(c => c.Code)
            .Take(MaxItems)
            .Select(c => new
            {
                c.Code,
                c.Name,
                c.Market
            })
            .ToListAsync(ct);

        return new Response
        {
            List = [..list.Select(c => new Response.Item
            {
                Code = c.Code,
                Name = c.Name,
                Market = c.Market.ToString()
            })]
        };
    }
}