using System.Text.Json;
using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Domain.Entities.Stocks.ValueObject;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Api.Stocks.GetDomesticSummary;

/// <summary>
/// 국내 증시 요약(메인) — 최신 거래일의 코스피·코스닥·KOSPI200 지수(IndexDailyPrice) + 글로벌 벤치마크 S&amp;P500·나스닥(WorldIndexSnapshot).
/// 각 카드에 최근 종가 스파크라인(과거→최신) 포함: 국내는 IndexDailyPrice 시계열, 글로벌은 WorldIndexSnapshot.Spark(JSON).
/// 등락종목수·상하한 top 집계는 GetMarketMovers 로 분리했다.
/// </summary>
internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    private const int SparkPoints = 30; // 스파크라인 최근 거래일 수

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var rows = new List<Response.Row>();

        var latestIndexDate = await db.IndexDailyPrice.AsNoTracking()
            .OrderByDescending(c => c.TradeDate)
            .Select(c => (DateOnly?)c.TradeDate)
            .FirstOrDefaultAsync(ct);

        // 국내 지수는 IndexDailyPrice 데이터가 있을 때만 (KRX 미수집·장중 등에도 글로벌 카드는 노출)
        if (latestIndexDate is DateOnly indexDate)
        {
            await AddIndexAsync(rows, "kospi", MarketIndexSeries.KOSPI, "코스피", indexDate, ct);
            await AddIndexAsync(rows, "kosdaq", MarketIndexSeries.KOSDAQ, "코스닥", indexDate, ct);
            await AddKospi200Async(rows, indexDate, ct);
        }

        // 글로벌 벤치마크 — IndexDailyPrice 유무와 무관하게 WorldIndexSnapshot 심볼로 항상 조회 + 표시명 오버라이드
        await AddGlobalAsync(rows, "sp500", "^gspc", "S&P 500", ct);
        await AddGlobalAsync(rows, "nasdaq", "^ixic", "나스닥", ct);

        return new Response { List = rows };
    }

    private async Task AddIndexAsync(
        List<Response.Row> rows,
        string key,
        MarketIndexSeries series,
        string indexName,
        DateOnly indexDate,
        CancellationToken ct
    ) {
        var idx = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.TradeDate == indexDate && c.Series == series && c.IndexName == indexName)
            .Select(c => new { c.Close, c.ChangeVal, c.FlucRateBp })
            .FirstOrDefaultAsync(ct);

        if (idx is null)
        {
            return;
        }

        rows.Add(new Response.Row
        {
            Key = key,
            Name = indexName,
            Close = idx.Close,
            ChangeVal = idx.ChangeVal,
            FlucRateBp = idx.FlucRateBp,
            TradeDate = indexDate.ToString("yyyy-MM-dd"),
            Spark = await IndexSparkAsync(series, indexName, indexDate, ct)
        });
    }

    private async Task AddKospi200Async(List<Response.Row> rows, DateOnly indexDate, CancellationToken ct)
    {
        var idx = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.TradeDate == indexDate && c.Series == MarketIndexSeries.KOSPI && c.IndexName.Contains("200"))
            .OrderBy(c => c.IndexName)
            .Select(c => new { c.IndexName, c.Close, c.ChangeVal, c.FlucRateBp })
            .FirstOrDefaultAsync(ct);

        if (idx is null)
        {
            return;
        }

        rows.Add(new Response.Row
        {
            Key = "kospi200",
            Name = idx.IndexName,
            Close = idx.Close,
            ChangeVal = idx.ChangeVal,
            FlucRateBp = idx.FlucRateBp,
            TradeDate = indexDate.ToString("yyyy-MM-dd"),
            Spark = await IndexSparkAsync(MarketIndexSeries.KOSPI, idx.IndexName, indexDate, ct)
        });
    }

    private async Task AddGlobalAsync(List<Response.Row> rows, string key, string symbol, string name, CancellationToken ct)
    {
        var idx = await db.WorldIndexSnapshot.AsNoTracking()
            .Where(c => c.Symbol == symbol)
            .Select(c => new { c.Close, c.ChangeVal, c.FlucRateBp, c.TradeDate, c.Spark })
            .FirstOrDefaultAsync(ct);

        if (idx is null)
        {
            return;
        }

        rows.Add(new Response.Row
        {
            Key = key,
            Name = name,
            Close = idx.Close,
            ChangeVal = idx.ChangeVal,
            FlucRateBp = idx.FlucRateBp,
            TradeDate = idx.TradeDate.ToString("yyyy-MM-dd"),
            Spark = ParseSpark(idx.Spark)
        });
    }

    /// <summary>지수 최근 종가 시계열(과거→최신) — asOf 거래일 기준 SparkPoints 개.</summary>
    private async Task<IReadOnlyList<decimal>> IndexSparkAsync(MarketIndexSeries series, string indexName, DateOnly asOf, CancellationToken ct)
    {
        var recent = await db.IndexDailyPrice.AsNoTracking()
            .Where(c => c.Series == series && c.IndexName == indexName && c.TradeDate <= asOf)
            .OrderByDescending(c => c.TradeDate)
            .Take(SparkPoints)
            .Select(c => c.Close)
            .ToListAsync(ct);

        recent.Reverse();
        return recent;
    }

    /// <summary>WorldIndexSnapshot.Spark(JSON decimal[]) 파싱 — null/오류는 빈 배열.</summary>
    private static IReadOnlyList<decimal> ParseSpark(string? sparkJson)
    {
        if (string.IsNullOrWhiteSpace(sparkJson))
        {
            return [];
        }

        try
        {
            return JsonSerializer.Deserialize<List<decimal>>(sparkJson) ?? [];
        }
        catch (JsonException)
        {
            return [];
        }
    }
}