using SSPCTester.Devices.Interfaces;
using SSPCTester.Logic.Calculation;
using Xunit;

namespace SSPCTester.Tests;

public class CurveMetricsTests
{
    /// <summary>构造一段 V(t) = Vmax*(1-exp(-t/tau)) 形状的上升曲线。</summary>
    private static CurveData MakeRising(double vMax = 28, double tauSec = 0.0005, int rate = 100_000, double duration = 0.01, double trigger = 0.0025)
    {
        int n = (int)(rate * duration);
        var v = new double[n];
        for (int i = 0; i < n; i++)
        {
            double t = (double)i / rate - trigger;
            v[i] = t <= 0 ? 0 : vMax * (1 - System.Math.Exp(-t / tauSec));
        }
        return new CurveData { SampleRateHz = rate, TriggerTimeSec = trigger, Voltage = v };
    }

    private static CurveData MakeFalling(double vMax = 28, double tauSec = 0.0005, int rate = 100_000, double duration = 0.01, double trigger = 0.0025)
    {
        int n = (int)(rate * duration);
        var v = new double[n];
        for (int i = 0; i < n; i++)
        {
            double t = (double)i / rate - trigger;
            v[i] = t <= 0 ? vMax : vMax * System.Math.Exp(-t / tauSec);
        }
        return new CurveData { SampleRateHz = rate, TriggerTimeSec = trigger, Voltage = v };
    }

    [Fact]
    public void OnTimeMs_ReachesNinetyPercent_AtAboutMinusLogPointOneTau()
    {
        var c = MakeRising();
        double onMs = CurveMetrics.OnTimeMs(c, 28, 0.9);
        // 90% 时刻 t = -tau * ln(0.1) ≈ 1.151 ms
        Assert.InRange(onMs, 1.1, 1.2);
    }

    [Fact]
    public void RiseTimeMs_TonToNinety_AboutNinetyPercentTime()
    {
        var c = MakeRising();
        double rt = CurveMetrics.RiseTimeMs(c, 28);
        // ln(0.9/0.1) = ln 9 ≈ 2.197；rt = tau * 2.197 ≈ 1.099 ms
        Assert.InRange(rt, 1.1, 1.2);
    }

    [Fact]
    public void AnalyzeRising_ReturnsTonToNinetyIndexesAndDuration()
    {
        var c = MakeRising();
        var mark = CurveMetrics.AnalyzeRising(c, 28);
        int triggerIndex = (int)Math.Round(c.TriggerTimeSec * c.SampleRateHz);
        int expectedEnd = CurveMetrics.FirstReachIndex(c.Voltage, 28 * 0.9, rising: true, triggerIndex);
        int expectedStart = triggerIndex + 1;

        Assert.True(mark.IsValid);
        Assert.Equal(expectedStart, mark.StartIndex);
        Assert.Equal(expectedEnd, mark.EndIndex);
        Assert.Equal(c.Voltage[expectedStart], mark.StartThresholdV, 6);
        Assert.Equal((c.TimeAt(expectedEnd) - c.TimeAt(expectedStart)) * 1000.0, mark.DurationMs, 6);
        Assert.Equal(mark.DurationMs, CurveMetrics.RiseTimeMs(c, 28), 6);
    }

    [Fact]
    public void OffTimeMs_FallingToTenPercent()
    {
        var c = MakeFalling();
        double off = CurveMetrics.OffTimeMs(c, 28, 0.1);
        Assert.InRange(off, 1.1, 1.2);
    }

    [Fact]
    public void AnalyzeFalling_ReturnsStableHighToTenIndexesAndDuration()
    {
        var c = MakeFalling();
        var mark = CurveMetrics.AnalyzeFalling(c, 28);
        int triggerIndex = (int)Math.Round(c.TriggerTimeSec * c.SampleRateHz);
        int expectedEnd = CurveMetrics.FirstReachIndex(c.Voltage, 28 * 0.1, rising: false, triggerIndex);
        int expectedStart = triggerIndex + 1;

        Assert.True(mark.IsValid);
        Assert.Equal(expectedStart, mark.StartIndex);
        Assert.Equal(expectedEnd, mark.EndIndex);
        Assert.Equal(c.Voltage[expectedStart], mark.StartThresholdV, 6);
        Assert.Equal((c.TimeAt(expectedEnd) - c.TimeAt(expectedStart)) * 1000.0, mark.DurationMs, 6);
        Assert.Equal(mark.DurationMs, CurveMetrics.FallTimeMs(c, 28), 6);
    }

    [Fact]
    public void AnalyzeRising_StartsAtSustainedRiseAndEndsAtFirstRawNinetyPercent()
    {
        const int rate = 1_000_000;
        const double trigger = 0.0002;
        int triggerIndex = (int)Math.Round(trigger * rate);
        var v = Enumerable.Repeat(0.0, 2_000).ToArray();

        v[triggerIndex + 100] = -4.0;
        v[triggerIndex + 101] = 2.0;
        v[triggerIndex + 102] = 0.0;

        int riseStart = triggerIndex + 500;
        for (int i = riseStart; i < v.Length; i++)
        {
            double progress = Math.Clamp((i - riseStart) / 60.0, 0.0, 1.0);
            v[i] = 5.0 * progress;
        }

        var curve = new CurveData { SampleRateHz = rate, TriggerTimeSec = trigger, Voltage = v };
        var mark = CurveMetrics.AnalyzeRising(curve, 5.0);
        int expectedEnd = CurveMetrics.FirstReachIndex(v, 4.5, rising: true, riseStart);

        Assert.True(mark.IsValid);
        Assert.InRange(mark.StartIndex, riseStart - 3, riseStart + 5);
        Assert.Equal(expectedEnd, mark.EndIndex);
    }

    [Fact]
    public void AnalyzeFalling_StartsAtSlowDropAndEndsAtFirstRawTenPercent()
    {
        const int rate = 1_000_000;
        const double trigger = 0.0002;
        int triggerIndex = (int)Math.Round(trigger * rate);
        var v = Enumerable.Repeat(3.0, 2_000).ToArray();

        int fallStart = triggerIndex + 300;
        for (int i = fallStart; i < triggerIndex + 850; i++)
            v[i] = 3.0 - 0.55 * (i - fallStart) / 550.0;

        v[triggerIndex + 850] = 5.0;
        for (int i = triggerIndex + 851; i < v.Length; i++)
        {
            double progress = Math.Clamp((i - (triggerIndex + 851)) / 45.0, 0.0, 1.0);
            v[i] = Math.Max(-0.2, 2.45 * (1.0 - progress));
        }

        var curve = new CurveData { SampleRateHz = rate, TriggerTimeSec = trigger, Voltage = v };
        var mark = CurveMetrics.AnalyzeFalling(curve, 3.0);
        int expectedEnd = CurveMetrics.FirstReachIndex(v, 0.3, rising: false, fallStart);

        Assert.True(mark.IsValid);
        Assert.InRange(mark.StartIndex, fallStart - 5, fallStart + 30);
        Assert.Equal(expectedEnd, mark.EndIndex);
    }

    [Fact]
    public void AnalyzeTransition_ReturnsInvalidWhenThresholdsAreNotReached()
    {
        var risingCurve = new CurveData
        {
            SampleRateHz = 100_000,
            TriggerTimeSec = 0,
            Voltage = Enumerable.Repeat(0.0, 100).ToArray()
        };
        var fallingCurve = new CurveData
        {
            SampleRateHz = 100_000,
            TriggerTimeSec = 0,
            Voltage = Enumerable.Repeat(28.0, 100).ToArray()
        };

        var rising = CurveMetrics.AnalyzeRising(risingCurve, 28);
        var falling = CurveMetrics.AnalyzeFalling(fallingCurve, 28);

        Assert.False(rising.IsValid);
        Assert.False(falling.IsValid);
        Assert.Equal(-1, rising.StartIndex);
        Assert.Equal(-1, falling.EndIndex);
        Assert.True(double.IsNaN(CurveMetrics.RiseTimeMs(risingCurve, 28)));
        Assert.True(double.IsNaN(CurveMetrics.FallTimeMs(fallingCurve, 28)));
    }

    [Fact]
    public void EstimateVMax_NearActualMax()
    {
        var c = MakeRising();
        double v = CurveMetrics.EstimateVMax(c.Voltage);
        Assert.InRange(v, 27, 28.001);
    }
}

public class PowerLossTests
{
    [Fact]
    public void VoltageDrop_Subtracts()
        => Assert.Equal(1.5, PowerLoss.VoltageDrop(28, 26.5), 3);

    [Fact]
    public void Loss_PinMinusPout()
        => Assert.Equal(28 * 1.0 - 26.5 * 1.0, PowerLoss.LossWatts(28, 1, 26.5, 1), 3);

    [Fact]
    public void Efficiency_Percentage()
    {
        double e = PowerLoss.EfficiencyPct(28, 1, 26.5, 1);
        Assert.InRange(e, 94, 95);
    }

    [Fact]
    public void Efficiency_ZeroInputReturnsZero()
        => Assert.Equal(0.0, PowerLoss.EfficiencyPct(0, 0, 0, 0));
}