using System.Globalization;
using System.Text;
using Application.Abstractions.Data;
using Domain.Entities.Forum.Briefings;
using Domain.Entities.Stocks.ValueObject;
using Microsoft.EntityFrameworkCore;
using PostEntity = Domain.Entities.Forum.Posts.Post;

namespace Application.Helpers;

/// <summary>
/// 장전 브리핑 본문 조립 + 발행 엔진 (d2 §③·§⑥ M3 DailyBriefingPublisher).
/// 전일 지수(IndexDailyPrice 최신 KOSPI/KOSDAQ), 등락 상위/하위 종목(StockDailyPrice 최신 거래일 ChangeRate),
/// 주요 공시(Disclosure 최근)를 취합해 briefing 보드에 시스템 계정(MemberID=null)으로 IsNotice Post 를 발행하고
/// DailyBriefing 기록을 남긴다. BriefingDate 로 멱등(이미 발행됐으면 skip).
///
/// 스케줄은 Infrastructure 의 HostedService(DailyBriefingPublisher)가 담당하고, 여기서는 순수 조립/발행 로직만
/// 다뤄 IAppDbContext 만으로 단위 테스트가 가능하도록 분리했다 (PredictionSettlementEngine 패턴).
/// 시스템 작성자 정책: Post.MemberID 는 nullable 이므로 전용 Member 없이 null + Name="개미투자" 로 발행한다(가장 단순).
/// </summary>
public static class DailyBriefingComposer
{
    /// <summary>시스템 작성자 표시명 (Post.MemberID=null).</summary>
    public const string SystemAuthorName = "개미투자";

    private const int TopMoversCount = 5;
    private const int DisclosureCount = 10;

    /// <summary>발행 결과 (배치 로그/테스트용).</summary>
    public readonly record struct PublishResult(bool Published, int PostID, bool AlreadyExisted);

    /// <summary>
    /// briefingDate 기준 장전 브리핑을 조립·발행한다. 이미 해당 일자로 발행됐으면 skip(멱등).
    /// 발행 시 briefing 보드는 lazy 시드되며, 반환값으로 발행 여부/PostID 를 준다.
    /// </summary>
    public static async Task<PublishResult> PublishAsync(IAppDbContext db, DateOnly briefingDate, CancellationToken ct)
    {
        var existing = await db.DailyBriefing.AsNoTracking()
            .Where(c => c.BriefingDate == briefingDate)
            .Select(c => c.PostID)
            .FirstOrDefaultAsync(ct);

        if (existing != 0)
        {
            return new PublishResult(false, existing, true);
        }

        var body = await ComposeBodyAsync(db, ct);
        var subject = $"[장전 시황] {briefingDate:yyyy-MM-dd}";

        var boardID = await BoardSeeder.ResolveBriefingBoardIDAsync(db, ct);

        var post = new PostEntity
        {
            BoardID = boardID,
            MemberID = null,
            Name = SystemAuthorName,
            Subject = subject,
            Content = body,
            IsNotice = true
        };

        await db.Post.AddAsync(post, ct);
        await db.SaveChangesAsync(ct); // Post.ID(IDENTITY) 확보 — DailyBriefing FK 에 필요

        await db.DailyBriefing.AddAsync(DailyBriefing.Create(briefingDate, post.ID), ct);

        // Board 글 수 증가 (일반 작성 핸들러와 동일 계약)
        var boardEntity = await db.Board.FirstOrDefaultAsync(c => c.ID == boardID, ct);
        if (boardEntity is not null)
        {
            boardEntity.Posts++;
            boardEntity.UpdatedAt = DateTime.UtcNow;

            var boardGroup = await db.BoardGroup.FirstOrDefaultAsync(c => c.ID == boardEntity.BoardGroupID, ct);
            if (boardGroup is not null)
            {
                boardGroup.Posts++;
                boardGroup.UpdatedAt = DateTime.UtcNow;
            }
        }

        await db.SaveChangesAsync(ct);

        return new PublishResult(true, post.ID, false);
    }

    /// <summary>전일 지수 + 등락 상위/하위 + 주요 공시로 HTML 본문을 조립한다.</summary>
    private static async Task<string> ComposeBodyAsync(IAppDbContext db, CancellationToken ct)
    {
        var sb = new StringBuilder();

        // ── 전일 지수 (KOSPI/KOSDAQ 최신 종가·등락) ──
        sb.Append("<h3>전일 지수</h3>");
        var indices = await LoadLatestIndicesAsync(db, ct);
        if (indices.Count > 0)
        {
            sb.Append("<ul>");
            foreach (var idx in indices)
            {
                var rate = (idx.FlucRateBp / 100m).ToString("0.00", CultureInfo.InvariantCulture);
                var sign = idx.FlucRateBp >= 0 ? "+" : "";
                sb.Append(CultureInfo.InvariantCulture, $"<li>{Escape(idx.IndexName)}: {idx.Close.ToString("N2", CultureInfo.InvariantCulture)} ({sign}{idx.ChangeVal.ToString("N2", CultureInfo.InvariantCulture)}, {sign}{rate}%)</li>");
            }
            sb.Append("</ul>");
        }
        else
        {
            sb.Append("<p>데이터 없음</p>");
        }

        // ── 등락 상위/하위 종목 (최신 거래일 ChangeRate) ──
        var latestTradeDate = await db.StockDailyPrice.AsNoTracking()
            .OrderByDescending(c => c.TradingDate)
            .Select(c => (DateOnly?)c.TradingDate)
            .FirstOrDefaultAsync(ct);

        if (latestTradeDate is DateOnly tradeDate)
        {
            var gainers = await LoadMoversAsync(db, tradeDate, top: true, ct);
            var losers = await LoadMoversAsync(db, tradeDate, top: false, ct);

            sb.Append("<h3>등락 상위</h3>");
            AppendMovers(sb, gainers);

            sb.Append("<h3>등락 하위</h3>");
            AppendMovers(sb, losers);
        }

        // ── 주요 공시 (최근 접수) ──
        sb.Append("<h3>주요 공시</h3>");
        var disclosures = await db.Disclosure.AsNoTracking()
            .OrderByDescending(c => c.RceptDt).ThenByDescending(c => c.RceptNo)
            .Take(DisclosureCount)
            .Select(c => new { c.CorpName, c.ReportNm, c.RceptDt })
            .ToListAsync(ct);

        if (disclosures.Count > 0)
        {
            sb.Append("<ul>");
            foreach (var d in disclosures)
            {
                sb.Append(CultureInfo.InvariantCulture, $"<li>[{d.RceptDt:yyyy-MM-dd}] {Escape(d.CorpName)} — {Escape(d.ReportNm)}</li>");
            }
            sb.Append("</ul>");
        }
        else
        {
            sb.Append("<p>데이터 없음</p>");
        }

        return sb.ToString();
    }

    private sealed record IndexRow(string IndexName, decimal Close, decimal ChangeVal, int FlucRateBp);

    /// <summary>KOSPI/KOSDAQ 각 계열에서 최신 거래일 지수 1건씩 로드.</summary>
    private static async Task<List<IndexRow>> LoadLatestIndicesAsync(IAppDbContext db, CancellationToken ct)
    {
        var rows = new List<IndexRow>();
        foreach (var series in new[] { MarketIndexSeries.KOSPI, MarketIndexSeries.KOSDAQ })
        {
            var idx = await db.IndexDailyPrice.AsNoTracking()
                .Where(c => c.Series == series)
                .OrderByDescending(c => c.TradeDate).ThenBy(c => c.IndexName)
                .Select(c => new IndexRow(c.IndexName, c.Close, c.ChangeVal, c.FlucRateBp))
                .FirstOrDefaultAsync(ct);

            if (idx is not null)
            {
                rows.Add(idx);
            }
        }
        return rows;
    }

    private sealed record MoverRow(string Name, string Code, decimal ChangeRate, int Close);

    /// <summary>최신 거래일 종목 시세를 ChangeRate 내림차순(top)/오름차순으로 N건 로드 — Stock 조인으로 종목명 표기.</summary>
    private static async Task<List<MoverRow>> LoadMoversAsync(IAppDbContext db, DateOnly tradeDate, bool top, CancellationToken ct)
    {
        var query = db.StockDailyPrice.AsNoTracking().Where(c => c.TradingDate == tradeDate);
        var ordered = top ? query.OrderByDescending(c => c.ChangeRate) : query.OrderBy(c => c.ChangeRate);

        var rows = await ordered
            .Take(TopMoversCount)
            .Join(db.Stock.AsNoTracking(), price => price.StockID, stock => stock.ID, (price, stock) => new MoverRow(stock.Name, stock.Code, price.ChangeRate, price.Close))
            .ToListAsync(ct);

        return rows;
    }

    private static void AppendMovers(StringBuilder sb, List<MoverRow> movers)
    {
        if (movers.Count == 0)
        {
            sb.Append("<p>데이터 없음</p>");
            return;
        }

        sb.Append("<ul>");
        foreach (var m in movers)
        {
            var rate = m.ChangeRate.ToString("0.00", CultureInfo.InvariantCulture);
            var sign = m.ChangeRate >= 0 ? "+" : "";
            sb.Append(CultureInfo.InvariantCulture, $"<li>{Escape(m.Name)} (${m.Code}): {m.Close.ToString("N0", CultureInfo.InvariantCulture)}원 ({sign}{rate}%)</li>");
        }
        sb.Append("</ul>");
    }

    private static string Escape(string value)
    {
        return value.Replace("&", "&amp;", StringComparison.Ordinal).Replace("<", "&lt;", StringComparison.Ordinal).Replace(">", "&gt;", StringComparison.Ordinal);
    }
}