using SSPCTester.Devices.Interfaces;

namespace SSPCTester.Logic.Calculation;

/// <summary>
/// 曲线指标计算（纯函数，可单测）。
/// 覆盖开发文档 §6.4 中 1.1-1.6 指标。
/// </summary>
public static class CurveMetrics
{
    /// <summary>查找第一个达到 vTarget 的样点索引；找不到返回 -1。</summary>
    public static int FirstReachIndex(double[] v, double vTarget, bool rising = true, int startIndex = 0)
    {
        if (v == null || v.Length == 0) return -1;
        if (startIndex < 0) startIndex = 0;
        for (int i = startIndex; i < v.Length; i++)
        {
            if (rising ? v[i] >= vTarget : v[i] <= vTarget) return i;
        }
        return -1;
    }

    /// <summary>
    /// 开启时间（ms）：控制信号发出（curve.TriggerTimeSec）到电压达到 Vmax 的 thresholdRatio。
    /// </summary>
    public static double OnTimeMs(CurveData curve, double vMax, double thresholdRatio = 0.9)
    {
        int idx = FirstReachIndex(curve.Voltage, vMax * thresholdRatio, rising: true);
        if (idx < 0) return double.NaN;
        double t = curve.TimeAt(idx) - curve.TriggerTimeSec;
        return t * 1000.0;
    }

    /// <summary>
    /// 关闭时间（ms）：控制信号撤销到电压降到 Vmax 的 thresholdRatio（如 10%）。
    /// </summary>
    public static double OffTimeMs(CurveData curve, double vMax, double thresholdRatio = 0.1)
    {
        int idx = FirstReachIndex(curve.Voltage, vMax * thresholdRatio, rising: false);
        if (idx < 0) return double.NaN;
        double t = curve.TimeAt(idx) - curve.TriggerTimeSec;
        return t * 1000.0;
    }

    /// <summary>
    /// 上升时间（ms）：电压从 Vmax * low 到 Vmax * high 的时间（默认 10% → 90%）。
    /// </summary>
    public static double RiseTimeMs(CurveData curve, double vMax, double lowRatio = 0.1, double highRatio = 0.9)
    {
        int iLow = FirstReachIndex(curve.Voltage, vMax * lowRatio, rising: true);
        if (iLow < 0) return double.NaN;
        int iHigh = FirstReachIndex(curve.Voltage, vMax * highRatio, rising: true, startIndex: iLow);
        if (iHigh < 0) return double.NaN;
        return (curve.TimeAt(iHigh) - curve.TimeAt(iLow)) * 1000.0;
    }

    /// <summary>
    /// 下降时间（ms）：电压从 Vmax * high 到 Vmax * low 的时间（默认 90% → 10%）。
    /// </summary>
    public static double FallTimeMs(CurveData curve, double vMax, double highRatio = 0.9, double lowRatio = 0.1)
    {
        int iHigh = FirstReachIndex(curve.Voltage, vMax * highRatio, rising: false);
        if (iHigh < 0) return double.NaN;
        int iLow = FirstReachIndex(curve.Voltage, vMax * lowRatio, rising: false, startIndex: iHigh);
        if (iLow < 0) return double.NaN;
        return (curve.TimeAt(iLow) - curve.TimeAt(iHigh)) * 1000.0;
    }

    /// <summary>从波形最大值估算 Vmax（去掉前后噪声，取 95 百分位以上的均值）。</summary>
    public static double EstimateVMax(double[] v)
    {
        if (v == null || v.Length == 0) return 0;
        var sorted = (double[])v.Clone();
        Array.Sort(sorted);
        int from = (int)(sorted.Length * 0.95);
        double sum = 0; int n = 0;
        for (int i = from; i < sorted.Length; i++) { sum += sorted[i]; n++; }
        return n > 0 ? sum / n : sorted[^1];
    }
}