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

namespace Application.Features.Api.Stocks.GetList;

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 query = db.Stock.AsNoTracking().Where(c => c.IsActive);

        if (request.Market.HasValue)
        {
            query = query.Where(c => c.Market == request.Market.Value);
        }

        var q = request.Q?.Trim();
        if (!string.IsNullOrEmpty(q))
        {
            query = query.Where(c => c.Name.Contains(q) || c.Code.StartsWith(q));
        }

        var total = await query.CountAsync(ct);

        // 방향 — 미지정/asc 외에는 내림차순 (숫자열 기본 desc, 기본 정렬도 desc)
        var desc = !string.Equals(request.Order, "asc", StringComparison.OrdinalIgnoreCase);

        // 정렬 — 기본 시가총액 내림차순. 거래대금(value)은 최근 거래일 StockDailyPrice 상관 서브쿼리 기준
        IOrderedQueryable<Domain.Entities.Stocks.Stock> ordered = request.Sort?.ToLowerInvariant() switch
        {
            "name" => desc ? query.OrderByDescending(c => c.Name) : query.OrderBy(c => c.Name),
            "price" => desc ? query.OrderByDescending(c => c.LastClosePrice) : query.OrderBy(c => c.LastClosePrice),
            "change" => desc ? query.OrderByDescending(c => c.LastChangeRate) : query.OrderBy(c => c.LastChangeRate),
            "value" => desc
                ? query.OrderByDescending(c => db.StockDailyPrice.Where(p => p.StockID == c.ID && p.TradingDate == c.LastTradingDate).Select(p => (long?)p.TradingValue).FirstOrDefault())
                : query.OrderBy(c => db.StockDailyPrice.Where(p => p.StockID == c.ID && p.TradingDate == c.LastTradingDate).Select(p => (long?)p.TradingValue).FirstOrDefault()),
            _ => desc ? query.OrderByDescending(c => c.MarketCap) : query.OrderBy(c => c.MarketCap)
        };

        var list = await ordered
            .ThenBy(c => c.Code)
            .Skip((page - 1) * perPage)
            .Take(perPage)
            .Select(c => new
            {
                c.Code,
                c.Name,
                c.Market,
                c.TradingStatus,
                c.LastTradingDate,
                c.LastClosePrice,
                c.LastChangeRate,
                c.MarketCap,
                // 전일 거래량·거래대금 — Stock denorm 에 없어 최근 거래일(LastTradingDate)의 StockDailyPrice 를 상관 서브쿼리로 조회
                Volume = db.StockDailyPrice.Where(p => p.StockID == c.ID && p.TradingDate == c.LastTradingDate).Select(p => (long?)p.Volume).FirstOrDefault(),
                TradingValue = db.StockDailyPrice.Where(p => p.StockID == c.ID && p.TradingDate == c.LastTradingDate).Select(p => (long?)p.TradingValue).FirstOrDefault()
            })
            .ToListAsync(ct);

        return new Response
        {
            Total = total,
            List = [..list.Select(c => new Response.Row
            {
                Code = c.Code,
                Name = c.Name,
                Market = c.Market.ToString(),
                TradingStatus = c.TradingStatus.ToString(),
                LastTradingDate = c.LastTradingDate,
                ClosePrice = c.LastClosePrice,
                ChangeRate = c.LastChangeRate,
                MarketCap = c.MarketCap,
                Volume = c.Volume,
                TradingValue = c.TradingValue
            })]
        };
    }
}