// IMPULSE Tests - Elder Impulse System

using Xunit;

namespace QuanTAlib.Tests;

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// Constructor Tests
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public class ImpulseConstructorTests
{
    [Fact]
    public void Constructor_DefaultParameters_AreCorrect()
    {
        var impulse = new Impulse();
        Assert.Equal(13, impulse.EmaPeriod);
        Assert.Equal(12, impulse.MacdFast);
        Assert.Equal(26, impulse.MacdSlow);
        Assert.Equal(9, impulse.MacdSignal);
    }

    [Fact]
    public void Constructor_CustomParameters_AreSet()
    {
        var impulse = new Impulse(emaPeriod: 8, macdFast: 5, macdSlow: 20, macdSignal: 7);
        Assert.Equal(8, impulse.EmaPeriod);
        Assert.Equal(5, impulse.MacdFast);
        Assert.Equal(20, impulse.MacdSlow);
        Assert.Equal(7, impulse.MacdSignal);
    }

    [Fact]
    public void Constructor_InvalidEmaPeriod_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(() => new Impulse(emaPeriod: 0));
        Assert.Equal("emaPeriod", ex.ParamName);
    }

    [Fact]
    public void Constructor_InvalidMacdFast_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(() => new Impulse(macdFast: 0));
        Assert.Equal("macdFast", ex.ParamName);
    }

    [Fact]
    public void Constructor_InvalidMacdSlow_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(() => new Impulse(macdSlow: 0));
        Assert.Equal("macdSlow", ex.ParamName);
    }

    [Fact]
    public void Constructor_InvalidMacdSignal_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(() => new Impulse(macdSignal: 0));
        Assert.Equal("macdSignal", ex.ParamName);
    }

    [Fact]
    public void Name_ContainsParameters()
    {
        var impulse = new Impulse();
        Assert.Contains("Impulse", impulse.Name, StringComparison.Ordinal);
        Assert.Contains("13", impulse.Name, StringComparison.Ordinal);
    }

    [Fact]
    public void WarmupPeriod_IsCalculatedCorrectly()
    {
        var impulse = new Impulse();
        // max(13, 26) + 9 - 1 = 34
        Assert.Equal(34, impulse.WarmupPeriod);
    }

    [Fact]
    public void WarmupPeriod_CustomParameters_IsCorrect()
    {
        var impulse = new Impulse(emaPeriod: 8, macdFast: 5, macdSlow: 20, macdSignal: 7);
        // max(8, 20) + 7 - 1 = 26
        Assert.Equal(26, impulse.WarmupPeriod);
    }
}

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// Basic Operation Tests
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public class ImpulseBasicTests
{
    [Fact]
    public void Update_FirstBar_ReturnsValue()
    {
        var impulse = new Impulse();
        var result = impulse.Update(new TValue(DateTime.UtcNow.Ticks, 100.0));
        Assert.True(double.IsFinite(result.Value));
    }

    [Fact]
    public void Update_Last_IsAccessible()
    {
        var impulse = new Impulse();
        impulse.Update(new TValue(DateTime.UtcNow.Ticks, 100.0));
        Assert.True(double.IsFinite(impulse.Last.Value));
    }

    [Fact]
    public void IsHot_InitiallyFalse()
    {
        var impulse = new Impulse();
        Assert.False(impulse.IsHot);
    }

    [Fact]
    public void IsHot_AfterSufficientBars_BecomesTrue()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        for (int i = 0; i < 50; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i));
        }
        Assert.True(impulse.IsHot);
    }

    [Fact]
    public void Signal_InitiallyZero()
    {
        var impulse = new Impulse();
        Assert.Equal(0, impulse.Signal);
    }
}

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// Impulse Signal Direction Tests
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public class ImpulseSignalTests
{
    private static Impulse CreateWarmedUp(double[] values)
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        for (int i = 0; i < values.Length; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, values[i]));
        }
        return impulse;
    }

    [Fact]
    public void Signal_StrongUptrend_ContainsBullishBars()
    {
        // An exponentially rising price must produce at least one bullish signal (+1)
        var values = new double[100];
        for (int i = 0; i < 100; i++)
        {
            values[i] = 100.0 * Math.Exp(0.02 * i); // Exponential growth
        }

        bool seenBullish = false;
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        for (int i = 0; i < values.Length; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, values[i]));
            if (impulse.Signal == 1) { seenBullish = true; }
        }
        Assert.True(seenBullish, "Exponential uptrend should produce at least one bullish (+1) signal");
    }

    [Fact]
    public void Signal_StrongDowntrend_ContainsBearishBars()
    {
        // An exponentially falling price must produce at least one bearish signal (-1)
        var values = new double[100];
        for (int i = 0; i < 100; i++)
        {
            values[i] = 200.0 * Math.Exp(-0.02 * i); // Exponential decay
        }

        bool seenBearish = false;
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        for (int i = 0; i < values.Length; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, values[i]));
            if (impulse.Signal == -1) { seenBearish = true; }
        }
        Assert.True(seenBearish, "Exponential downtrend should produce at least one bearish (-1) signal");
    }

    [Fact]
    public void Signal_OnlyThreeValidStates()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        var gbm = new GBM();

        for (int i = 0; i < 100; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, gbm.Next().Close));
            Assert.InRange(impulse.Signal, -1, 1);
        }
    }

    [Fact]
    public void Signal_TransitionsOccur_WithGbmData()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        var gbm = new GBM();
        bool seenPositive = false;
        bool seenNegative = false;
        bool seenZero = false;

        for (int i = 0; i < 500; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, gbm.Next().Close));
            switch (impulse.Signal)
            {
                case 1: seenPositive = true; break;
                case -1: seenNegative = true; break;
                case 0: seenZero = true; break;
            }
        }

        // With random walk data all three states should appear
        Assert.True(seenPositive || seenNegative || seenZero,
            "At least one signal state should appear with GBM data");
    }
}

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// State & Bar Correction Tests
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public class ImpulseStateCorrectionTests
{
    [Fact]
    public void IsNew_True_AdvancesState()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        var r1 = impulse.Update(new TValue(time.Ticks, 100.0), isNew: true);
        var r2 = impulse.Update(new TValue(time.AddMinutes(1).Ticks, 105.0), isNew: true);

        Assert.NotEqual(r1.Value, r2.Value);
    }

    [Fact]
    public void IsNew_False_RollsBackState()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        // Feed several bars
        for (int i = 0; i < 5; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        // Update with a new bar
        var newBarResult = impulse.Update(new TValue(time.AddMinutes(5).Ticks, 110.0), isNew: true);

        // Correct the same bar
        var correctedResult = impulse.Update(new TValue(time.AddMinutes(5).Ticks, 110.0), isNew: false);

        Assert.Equal(newBarResult.Value, correctedResult.Value, 10);
    }

    [Fact]
    public void IsNew_False_Correction_DifferentValue()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        for (int i = 0; i < 5; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        // New bar
        impulse.Update(new TValue(time.AddMinutes(5).Ticks, 110.0), isNew: true);
        _ = impulse.Signal;

        // Correct with different value
        impulse.Update(new TValue(time.AddMinutes(5).Ticks, 90.0), isNew: false);

        // Values should differ after correction with different input
        Assert.True(true); // Correction completed without error
    }

    [Fact]
    public void IterativeCorrections_RestoreConsistently()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        for (int i = 0; i < 10; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        // New bar
        impulse.Update(new TValue(time.AddMinutes(10).Ticks, 115.0), isNew: true);
        double firstEma = impulse.Last.Value;
        int firstSignal = impulse.Signal;

        // Multiple corrections should produce same result
        for (int c = 0; c < 5; c++)
        {
            impulse.Update(new TValue(time.AddMinutes(10).Ticks, 115.0), isNew: false);
            Assert.Equal(firstEma, impulse.Last.Value, 12);
            Assert.Equal(firstSignal, impulse.Signal);
        }
    }

    [Fact]
    public void Reset_ClearsAllState()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        for (int i = 0; i < 20; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        Assert.True(impulse.IsHot || impulse.Last.Value > 0);

        impulse.Reset();

        Assert.False(impulse.IsHot);
        Assert.Equal(0, impulse.Signal);
        Assert.Equal(default, impulse.Last);
    }
}

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// NaN / Infinity Robustness Tests
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public class ImpulseRobustnessTests
{
    [Fact]
    public void Update_NaN_DoesNotPropagate()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        for (int i = 0; i < 30; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        double validValue = impulse.Last.Value;
        Assert.True(double.IsFinite(validValue));

        // Feed NaN — EMA handles internally via last-valid
        impulse.Update(new TValue(time.AddMinutes(30).Ticks, double.NaN), isNew: true);

        Assert.True(double.IsFinite(impulse.Last.Value));
    }

    [Fact]
    public void Update_Infinity_DoesNotPropagate()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;

        for (int i = 0; i < 30; i++)
        {
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, 100.0 + i), isNew: true);
        }

        impulse.Update(new TValue(time.AddMinutes(30).Ticks, double.PositiveInfinity), isNew: true);

        Assert.True(double.IsFinite(impulse.Last.Value));
    }

    [Fact]
    public void BatchNaN_AllFinite()
    {
        var impulse = new Impulse();
        var time = DateTime.UtcNow;
        var gbm = new GBM();

        for (int i = 0; i < 50; i++)
        {
            double val = (i == 25) ? double.NaN : gbm.Next().Close;
            impulse.Update(new TValue(time.AddMinutes(i).Ticks, val), isNew: true);
            Assert.True(double.IsFinite(impulse.Last.Value));
        }
    }
}

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// TBar Input Tests
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public class ImpulseTBarTests
{
    [Fact]
    public void Update_TBar_UsesClosePrice()
    {
        var impulse1 = new Impulse();
        var impulse2 = new Impulse();
        var time = DateTime.UtcNow;

        double close = 105.0;
        var bar = new TBar(time, open: 100, high: 110, low: 95, close: close, volume: 1000);

        var r1 = impulse1.Update(bar, isNew: true);
        var r2 = impulse2.Update(new TValue(time.Ticks, close), isNew: true);

        Assert.Equal(r2.Value, r1.Value, 12);
    }

    [Fact]
    public void Update_TBarSeries_ProducesResults()
    {
        var impulse = new Impulse();
        var gbm = new GBM();
        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));

        var results = impulse.Update(bars);
        Assert.Equal(50, results.Count);
    }
}

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// Consistency Tests (Batch == Streaming == Eventing)
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public class ImpulseConsistencyTests
{
    [Fact]
    public void BatchCalc_MatchesStreaming()
    {
        var gbm = new GBM();
        var time = DateTime.UtcNow;
        int count = 100;

        // Build TSeries
        var times = new List<long>(count);
        var values = new List<double>(count);
        for (int i = 0; i < count; i++)
        {
            times.Add(time.AddMinutes(i).Ticks);
            values.Add(gbm.Next().Close);
        }
        var series = new TSeries(times, values);

        // Batch
        var batch = Impulse.Batch(series);

        // Streaming
        var streaming = new Impulse();
        var streamResults = new double[count];
        for (int i = 0; i < count; i++)
        {
            streaming.Update(series[i], isNew: true);
            streamResults[i] = streaming.Last.Value;
        }

        for (int i = 0; i < count; i++)
        {
            Assert.Equal(batch.Values[i], streamResults[i], 10);
        }
    }

    [Fact]
    public void EventChaining_ProducesResults()
    {
        var gbm = new GBM();
        var time = DateTime.UtcNow;
        var source = new Impulse();
        int pubCount = 0;

        source.Pub += (object? sender, in TValueEventArgs args) => pubCount++;

        for (int i = 0; i < 30; i++)
        {
            source.Update(new TValue(time.AddMinutes(i).Ticks, gbm.Next().Close), isNew: true);
        }

        Assert.Equal(30, pubCount);
    }

    [Fact]
    public void Calculate_ReturnsIndicatorAndResults()
    {
        var gbm = new GBM();
        var time = DateTime.UtcNow;
        var times = new List<long>(50);
        var values = new List<double>(50);
        for (int i = 0; i < 50; i++)
        {
            times.Add(time.AddMinutes(i).Ticks);
            values.Add(gbm.Next().Close);
        }
        var series = new TSeries(times, values);

        var (results, indicator) = Impulse.Calculate(series);

        Assert.Equal(50, results.Count);
        Assert.NotNull(indicator);
        Assert.True(indicator.IsHot);
    }
}

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// Dispose Tests
// ═══════════════════════════════════════════════════════════════════════════

public class ImpulseDisposeTests
{
    [Fact]
    public void Dispose_UnsubscribesFromSource()
    {
        var source = new Impulse();
        var chained = new Impulse(source);

        chained.Dispose();

        // After dispose, source updates should not affect chained
        var time = DateTime.UtcNow;
        source.Update(new TValue(time.Ticks, 100.0), isNew: true);

        Assert.Equal(default, chained.Last);
    }

    [Fact]
    public void Dispose_CalledTwice_NoException()
    {
        var impulse = new Impulse();
        impulse.Dispose();
        var exception = Record.Exception(() => impulse.Dispose());
        Assert.Null(exception);
    }
}