namespace YLErp.Modules.SwapModule.Accrual;

/// <summary>
/// 计息政策（不可变配置）。把"算头算尾 / 单复利率 / 重置频率 / 年化天数"收敛为一处，
/// 取代旧代码里散落各处的 calcFirst/calcLast 布尔对与魔法数字。
///
/// 单/复利不再另立枚举——直接复用既有 DB 枚举 InterestTypeEnum（单利=0 / 复利=1），
/// 通过 <see cref="IsCompound"/> 暴露为类型安全的 bool。
/// </summary>
public sealed class AccrualPolicy
{
    /// <summary>算头算尾约定（AccrualBoundary，物理上杜绝 calcFirst/calcLast 传反）。</summary>
    public AccrualBoundary Convention { get; }

    /// <summary>是否复利（利滚利）。来自 DB 的 InterestTypeEnum；单利=false，复利=true。</summary>
    public bool IsCompound { get; }

    /// <summary>利率重置周期（天）。FR007 通常为 7；复利时亦为"利息并入本金"的周期。</summary>
    public int ResetPeriodDays { get; }

    /// <summary>年化基数（365 / 360）。</summary>
    public int AnnualDays { get; }

    /// <summary>是否年化（position.IsAnnualized）。决定利息是否再除以 <see cref="AnnualDays"/>；
    /// 与 <see cref="AnnualDays"/> 一同收敛 daycount 语义，不再作为裸 bool 散落在计息签名里。</summary>
    public bool IsAnnualized { get; }

    public AccrualPolicy(AccrualBoundary convention, bool isCompound, int resetPeriodDays, int annualDays, bool isAnnualized = false)
        => (Convention, IsCompound, ResetPeriodDays, AnnualDays, IsAnnualized) = (convention, isCompound, resetPeriodDays, annualDays, isAnnualized);

    /// <summary>从 swap_position 构造 EOD 计息政策（算头算尾，重置周期取 interest_rest_days）。</summary>
    public static AccrualPolicy BuildEod(DBModels.swap_position position, int annualDays, bool isCompound)
        => new(AccrualBoundary.Both, isCompound, position.interest_rest_days ?? 1, annualDays, position.IsAnnualized);
}