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

namespace Application.Features.Api.Stocks.GetEtp;

/// <summary>
/// 증권상품(ETF/ETN/ELW) 최신 거래일 목록 — 유형별 최신 TradeDate 행을 거래대금 내림차순으로 페이징 (KRX 증권상품 수집, 익명).
/// </summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    private const ushort MaxPerPage = 100;

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var page = request.Page < 1 ? 1 : request.Page;
        var perPage = request.PerPage is 0 or > MaxPerPage ? (ushort)20 : request.PerPage;

        var latest = await db.EtpDailyTrade.AsNoTracking()
            .Where(c => c.EtpType == request.Type)
            .OrderByDescending(c => c.TradeDate)
            .Select(c => (DateOnly?)c.TradeDate)
            .FirstOrDefaultAsync(ct);

        if (latest is null)
        {
            return new Response
            {
                Total = 0,
                TradeDate = null,
                List = []
            };
        }

        var query = db.EtpDailyTrade.AsNoTracking().Where(c => c.EtpType == request.Type && c.TradeDate == latest.Value);

        var total = await query.CountAsync(ct);

        var list = await query
            .OrderByDescending(c => c.TradeValue).ThenBy(c => c.Code)
            .Skip((page - 1) * perPage)
            .Take(perPage)
            .Select(c => new Response.Row
            {
                Type = c.EtpType,
                Code = c.Code,
                Name = c.Name,
                Close = c.Close,
                ChangeAmount = c.ChangeAmount,
                ChangeRate = c.ChangeRate,
                Volume = c.Volume,
                TradeValue = c.TradeValue,
                MarketCap = c.MarketCap,
                Nav = c.Nav,
                BaseIndexName = c.BaseIndexName,
                Underlying = c.Underlying
            })
            .ToListAsync(ct);

        return new Response
        {
            Total = total,
            TradeDate = latest.Value,
            List = list
        };
    }
}