using YLErp.DBModels;

namespace YLErp.Modules.SwapModule.Accrual;

/// <summary>
/// 融资腿逐日计息的跨日状态（不可变值对象）。
/// 这是"待实现利息"在日间滚动的快照，区别于已落库的 <c>swap_flow_event</c>。
///
/// 旧字段 → 领域命名映射（DB 列不可改，仅在边界处适配；本类内部一律用下列自描述名）：
/// <list type="table">
///   <item><term>TdInterestPrincipal</term><description>逐日滚动的计息本金 → <see cref="AccrualPrincipal"/></description></item>
///   <item><term>InterestIncomeSum</term><description>累计待实现利息 → <see cref="UnrealizedInterest"/></description></item>
///   <item><term>consumedInterest</term><description>历史已实现利息(legacy) → <see cref="RealizedInterest"/></description></item>
///   <item><term>ValueDate</term><description>快照截至日 → <see cref="ValueDate"/>（EOD 续接起算日，Bug C / 5-11 跳过需据此判断从哪天接续）。</description></item>
/// </list>
/// </summary>
public readonly struct AccrualState
{
    /// <summary>用于计算当日利息的计息本金。单利=名义本金基数；复利=本金+累计利息。</summary>
    public decimal AccrualPrincipal { get; }

    /// <summary>累计待实现（未平仓）利息。</summary>
    public decimal UnrealizedInterest { get; }

    /// <summary>历史各次平仓已确认的已实现利息，从剩余待实现中扣除。</summary>
    public decimal RealizedInterest { get; }

    /// <summary>快照截至日（来自 eod_swap_position.ValueDate）。编排层据此判断计息区间起点，避免 5-11 等"跳过日"误重算。</summary>
    public DateTime ValueDate { get; }

    public AccrualState(decimal accrualPrincipal, decimal unrealizedInterest, decimal realizedInterest, DateTime valueDate)
        => (AccrualPrincipal, UnrealizedInterest, RealizedInterest, ValueDate) = (accrualPrincipal, unrealizedInterest, realizedInterest, valueDate);

    /// <summary>向后兼容：未携带快照日期时（如纯内存构造）用默认日。</summary>
    public AccrualState(decimal accrualPrincipal, decimal unrealizedInterest, decimal realizedInterest)
        : this(accrualPrincipal, unrealizedInterest, realizedInterest, default) { }

    /// <summary>空状态（新开仓首个计息日之前）。</summary>
    public static readonly AccrualState Zero = new(0m, 0m, 0m);

    /// <summary>
    /// 从上一日日终归档 <see cref="eod_swap_position"/> 适配（边界适配：DB 列名 → 领域名）。
    /// 仅映射计息状态；名义本金基数 / 平仓比例 / 已实现利息等由调用方另行传入。
    /// </summary>
    public static AccrualState FromPreviousEod(eod_swap_position previousEod)
        => previousEod == null || previousEod.id == 0
            ? Zero
            : new AccrualState(previousEod.TdInterestPrincipal, previousEod.InterestIncomeSum, 0m, previousEod.ValueDate);
}