using System.ComponentModel.DataAnnotations;

namespace Domain.Entities.Stocks;

/// <summary>
/// 회원 관심종목 (Member → Stock). d0 §2.1 규약대로 char(6) Code 를 FK 없이 denorm 보관하고 쓰기 시 AnyAsync 로 사전 검증한다.
/// (MemberID, StockCode) UNIQUE — 토글로 등록/해제.
/// </summary>
public sealed class StockWatch
{
    [Key]
    public long ID { get; private set; }

    /// <summary>관심 등록 회원 ID</summary>
    public int MemberID { get; private set; }

    /// <summary>단축코드 (char 6) — Stock.Code denorm</summary>
    public string StockCode { get; private set; } = default!;

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

    private StockWatch() { }

    private StockWatch(int memberID, string stockCode)
    {
        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));
        }

        MemberID = memberID;
        StockCode = stockCode;
        CreatedAt = DateTime.UtcNow;
    }

    public static StockWatch Create(int memberID, string stockCode)
    {
        return new(memberID, stockCode);
    }
}