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

namespace Application.Features.Api.Stocks.GetStockDividends;

internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    private const ushort MaxPerPage = 200;

    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var input = request.CodeOrIsin?.Trim();
        if (string.IsNullOrEmpty(input))
        {
            return Result.Failure<Response>(Error.Problem("Stock.CodeRequired", "종목 코드가 필요합니다."));
        }

        // 단축코드(6자리) 우선 → Stock 조인으로 ISIN·IssucoCustno 확보. 미매칭이면 입력을 ISIN 으로 간주.
        var stock = await db.Stock.AsNoTracking()
            .Where(c => c.Code == input || c.ISIN == input)
            .Select(c => new { c.ISIN, c.IssucoCustno })
            .FirstOrDefaultAsync(ct);

        var isin = stock?.ISIN ?? input;
        var issucoCustno = stock?.IssucoCustno;

        var page = request.Page < 1 ? 1 : request.Page;
        var perPage = request.PerPage is 0 or > MaxPerPage ? (ushort)30 : request.PerPage;

        var query = db.Dividend.AsNoTracking().Where(c => c.Isin == isin);
        var total = await query.CountAsync(ct);

        var dividends = await query
            .OrderByDescending(c => c.RgtStdDt)
            .Skip((page - 1) * perPage)
            .Take(perPage)
            .Select(c => new
            {
                c.RgtStdDt,
                c.KorSecnNm,
                c.SecnKacdNm,
                c.Pval,
                c.CashAllocAmt,
                c.StkAllocRatio,
                c.MartpDivRate,
                c.Th1PayTermBeginDt
            })
            .ToListAsync(ct);

        // 권리락일·확정구분 결합 — DividendSchedule (IssucoCustno + 페이지 내 RgtStdDt). 세부유형별 여러 행이면 권리락일 있는 행 우선.
        var scheduleByDate = new Dictionary<DateOnly, (DateOnly? XrgtDt, string? FixType)>();

        if (issucoCustno is not null && dividends.Count > 0)
        {
            var dates = dividends.Select(c => c.RgtStdDt).Distinct().ToList();
            var schedules = await db.DividendSchedule.AsNoTracking()
                .Where(c => c.IssucoCustno == issucoCustno.Value && dates.Contains(c.RgtStdDt))
                .Select(c => new { c.RgtStdDt, c.XrgtDt, c.FixTpcd })
                .ToListAsync(ct);

            foreach (var s in schedules)
            {
                if (!scheduleByDate.TryGetValue(s.RgtStdDt, out var existing) || (existing.XrgtDt is null && s.XrgtDt is not null))
                {
                    scheduleByDate[s.RgtStdDt] = (s.XrgtDt, s.FixTpcd);
                }
            }
        }

        var list = dividends.Select(c =>
        {
            scheduleByDate.TryGetValue(c.RgtStdDt, out var sched);
            return new Response.Row
            {
                RgtStdDt = c.RgtStdDt,
                Name = c.KorSecnNm,
                SecurityKind = c.SecnKacdNm,
                FaceValue = c.Pval,
                CashPerShare = c.CashAllocAmt,
                StockAllocRatio = c.StkAllocRatio,
                MarketDividendRate = c.MartpDivRate,
                CashPayDate = c.Th1PayTermBeginDt,
                XrgtDt = sched.XrgtDt,
                FixType = sched.FixType
            };
        }).ToList();

        return new Response
        {
            Isin = isin,
            Total = total,
            List = list
        };
    }
}