using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Domain.Entities.Paper;

/// <summary>
/// 모의투자 체결 결과 — 주문당 1건(OrderID UNIQUE)으로 재실행 멱등을 보장한다 (d4 §③).
/// 배치(M2)가 TargetDate 시세로 기표한다. 매도 시 RealizedPnL(실현손익)을 기록.
/// </summary>
public class PaperFill
{
    [ForeignKey(nameof(OrderID))]
    public virtual PaperOrder Order { get; private set; } = null!;

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

    public int OrderID { get; private set; }

    /// <summary>체결가 (18,0)</summary>
    public decimal Price { get; private set; }

    public int Quantity { get; private set; }

    /// <summary>수수료 (토큰 sink)</summary>
    public decimal Fee { get; private set; }

    /// <summary>거래세 (매도 시, 토큰 sink)</summary>
    public decimal Tax { get; private set; }

    /// <summary>체결 총액 (Price × Quantity ± 수수료/세금 반영은 핸들러/배치 정책)</summary>
    public decimal Amount { get; private set; }

    /// <summary>매도 확정 손익 (매수는 null)</summary>
    public decimal? RealizedPnL { get; private set; }

    /// <summary>체결가 기준일</summary>
    public DateOnly PriceDate { get; private set; }

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

    private PaperFill() { }

    public static PaperFill Create(
        int orderID,
        decimal price,
        int quantity,
        decimal fee,
        decimal tax,
        decimal amount,
        DateOnly priceDate,
        decimal? realizedPnL = null
    ) {
        if (orderID <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(orderID));
        }

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

        return new PaperFill
        {
            OrderID = orderID,
            Price = price,
            Quantity = quantity,
            Fee = fee,
            Tax = tax,
            Amount = amount,
            PriceDate = priceDate,
            RealizedPnL = realizedPnL
        };
    }

    /// <summary>
    /// 신규 주문(ID 미확정) 케이스 — Order 내비게이션으로 생성해 EF 가 저장 시 FK(OrderID)를 자동 채우게 한다.
    /// 상폐 강제청산 등 시스템 주문+체결을 한 번에 저장할 때 사용 (d4 §⑨).
    /// </summary>
    public static PaperFill CreateFor(
        PaperOrder order,
        decimal price,
        int quantity,
        decimal fee,
        decimal tax,
        decimal amount,
        DateOnly priceDate,
        decimal? realizedPnL = null
    ) {
        ArgumentNullException.ThrowIfNull(order);

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

        return new PaperFill
        {
            Order = order,
            Price = price,
            Quantity = quantity,
            Fee = fee,
            Tax = tax,
            Amount = amount,
            PriceDate = priceDate,
            RealizedPnL = realizedPnL
        };
    }
}