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

namespace Application.Features.Api.Stocks.GetMacroIndicators;

/// <summary>
/// 거시경제지표 조회 — 지표코드별 최근 시점 추이 + 최신값 (KOSIS 수집, 익명). Codes 비면 적재된 전 지표.
/// 지표당 최근 Limit 시점을 시점 내림차순으로 뽑은 뒤 오름차순으로 되돌려(Points) 대시보드 차트에 그대로 쓴다.
/// </summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    private const int DefaultLimit = 60;
    private const int MaxLimit = 240;

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var limit = request.Limit > 0 ? Math.Min(request.Limit, MaxLimit) : DefaultLimit;
        var codes = request.Codes?.Where(c => !string.IsNullOrWhiteSpace(c)).Select(c => c.Trim()).ToList() ?? [];

        var query = db.MacroIndicator.AsNoTracking();

        if (codes.Count > 0)
        {
            query = query.Where(c => codes.Contains(c.Code));
        }

        var rows = await query
            .Select(c => new
            {
                c.Code,
                c.Name,
                c.Period,
                c.Value,
                c.Unit
            })
            .ToListAsync(ct);

        var indicators = rows
            .GroupBy(c => c.Code)
            .Select(g =>
            {
                var ordered = g.OrderByDescending(c => c.Period).Take(limit).OrderBy(c => c.Period).ToList();
                var latest = ordered.Count > 0 ? ordered[^1] : null;

                return new Response.Indicator
                {
                    Code = g.Key,
                    Name = latest?.Name ?? g.First().Name,
                    Unit = latest?.Unit,
                    LatestPeriod = latest?.Period,
                    LatestValue = latest?.Value,
                    Points = ordered.Select(c => new Response.Point
                    {
                        Period = c.Period,
                        Value = c.Value
                    }).ToList()
                };
            })
            .OrderBy(c => c.Code)
            .ToList();

        return new Response
        {
            Total = indicators.Count,
            List = indicators
        };
    }
}