using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Domain.Entities.Forum.Posts.ValueObject;
using Domain.Entities.Members;

namespace Domain.Entities.Forum.Posts;

/// <summary>
/// 예측글 (d2 §③) — 종목 방향/기간 예측을 작성 시점에 확정 기록하고, 채점 배치(M4)가 상태를 확정한다.
/// 작성 시 BasePrice(작성 시점 최신 T+1 종가)와 DueDate(영업일 + HorizonDays)를 스냅샷으로 고정한다.
/// 예측글이 삭제(IsDeleted)돼도 Prediction 은 유지·채점된다(삭제 회피 어뷰징 차단).
/// Stock FK 는 걸지 않는다(D1 소유). PostID 는 1:1(UQ).
/// M2 는 <b>Pending 생성만</b> — SettledPrice/SettledAt/상태 확정은 M4 PredictionSettlementService 소관.
/// </summary>
public class PostPrediction
{
    [ForeignKey(nameof(PostID))]
    public virtual Post Post { get; private set; } = null!;

    [ForeignKey(nameof(MemberID))]
    public virtual Member Member { get; private set; } = null!;

    [Key]
    public int ID { get; private set; }

    /// <summary>예측이 속한 게시글 (1:1)</summary>
    public int PostID { get; private set; }

    /// <summary>작성 회원</summary>
    public int MemberID { get; private set; }

    /// <summary>예측 종목 단축코드 (char 6)</summary>
    public string StockCode { get; private set; } = default!;

    /// <summary>예측 방향 (1=상승, 2=하락)</summary>
    public PredictionDirection Direction { get; private set; }

    /// <summary>작성 시점 기준가 (최신 T+1 종가 스냅샷)</summary>
    public decimal BasePrice { get; private set; }

    /// <summary>목표가 (선택) — 지정 시 도달 여부로 채점</summary>
    public decimal? TargetPrice { get; private set; }

    /// <summary>예측 기간 (영업일 수: 5 또는 20)</summary>
    public short HorizonDays { get; private set; }

    /// <summary>채점 예정일 (작성일 + HorizonDays 영업일)</summary>
    public DateOnly DueDate { get; private set; }

    /// <summary>상태 (0=Pending/1=Hit/2=Miss/3=Void)</summary>
    public PredictionStatus Status { get; private set; } = PredictionStatus.Pending;

    /// <summary>채점 시점 종가 (M4 확정)</summary>
    public decimal? SettledPrice { get; private set; }

    /// <summary>채점 일시 (M4 확정)</summary>
    public DateTime? SettledAt { get; private set; }

    public DateTime CreatedAt { get; private set; } = DateTime.UtcNow;

    private PostPrediction() { }

    /// <summary>Pending 예측 생성 (d2 §③ M2). 채점은 M4.</summary>
    public static PostPrediction Create(
        int postID,
        int memberID,
        string stockCode,
        PredictionDirection direction,
        decimal basePrice,
        short horizonDays,
        DateOnly dueDate,
        decimal? targetPrice = null)
    {
        if (postID <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(postID));
        }

        if (memberID <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(memberID));
        }

        if (stockCode is not { Length: 6 } || stockCode.Any(c => !char.IsAsciiDigit(c)))
        {
            throw new ArgumentException("stockCode must be 6 digits", nameof(stockCode));
        }

        if (!Enum.IsDefined(direction))
        {
            throw new ArgumentOutOfRangeException(nameof(direction));
        }

        if (basePrice <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(basePrice));
        }

        if (horizonDays <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(horizonDays));
        }

        return new PostPrediction
        {
            PostID = postID,
            MemberID = memberID,
            StockCode = stockCode,
            Direction = direction,
            BasePrice = basePrice,
            TargetPrice = targetPrice is > 0 ? targetPrice : null,
            HorizonDays = horizonDays,
            DueDate = dueDate,
            Status = PredictionStatus.Pending
        };
    }
}