namespace QuanTAlib.Tests;

public class JmaTests
{
    [Fact]
    public void Jma_Constructor_ValidatesInput()
    {
        // JMA doesn't explicitly throw on period currently, but let's check if it handles valid inputs
        var jma = new Jma(10);
        Assert.NotNull(jma);
    }

    [Fact]
    public void Jma_Calc_ReturnsValue()
    {
        var jma = new Jma(10);

        Assert.Equal(0, jma.Last.Value);

        TValue result = jma.Update(new TValue(DateTime.UtcNow, 100));

        Assert.True(result.Value > 0);
        Assert.Equal(result.Value, jma.Last.Value);
    }

    [Fact]
    public void Jma_SpanCalc_ValidatesInput()
    {
        double[] source = [1, 2, 3, 4, 5];
        double[] output = new double[5];
        double[] wrongSizeOutput = new double[3];

        // Period must be > 0
        Assert.Throws<ArgumentOutOfRangeException>(() => Jma.Batch(source.AsSpan(), output.AsSpan(), 0, 0));
        Assert.Throws<ArgumentOutOfRangeException>(() => Jma.Batch(source.AsSpan(), output.AsSpan(), -1, 0));

        // Output must be same length as source
        Assert.Throws<ArgumentException>(() => Jma.Batch(source.AsSpan(), wrongSizeOutput.AsSpan(), 3, 0));
    }

    [Fact]
    public void Jma_Calc_IsNew_False_UpdatesValue()
    {
        var jma = new Jma(10);

        jma.Update(new TValue(DateTime.UtcNow, 100));
        jma.Update(new TValue(DateTime.UtcNow, 110), isNew: true);
        double beforeUpdate = jma.Last.Value;

        jma.Update(new TValue(DateTime.UtcNow, 120), isNew: false);
        double afterUpdate = jma.Last.Value;

        // Update should change the value
        Assert.NotEqual(beforeUpdate, afterUpdate);
    }

    [Fact]
    public void Jma_Reset_ClearsState()
    {
        var jma = new Jma(10);

        jma.Update(new TValue(DateTime.UtcNow, 100));
        jma.Update(new TValue(DateTime.UtcNow, 105));
        double valueBefore = jma.Last.Value;

        jma.Reset();

        Assert.Equal(0, jma.Last.Value);

        // After reset, should accept new values
        jma.Update(new TValue(DateTime.UtcNow, 50));
        Assert.NotEqual(0, jma.Last.Value);
        Assert.NotEqual(valueBefore, jma.Last.Value);
    }

    [Fact]
    public void Jma_IsHot_BecomesTrueAfterWarmup()
    {
        var jma = new Jma(10);

        Assert.False(jma.IsHot);

        // Warmup for JMA(10) is approx 203 bars
        // ceil(20 + 80 * 10^0.36) = 203
        int warmup = (int)Math.Ceiling(20.0 + 80.0 * Math.Pow(10, 0.36));

        for (int i = 1; i < warmup; i++)
        {
            jma.Update(new TValue(DateTime.UtcNow, i * 10));
            Assert.False(jma.IsHot);
        }

        jma.Update(new TValue(DateTime.UtcNow, 100));
        Assert.True(jma.IsHot);
    }

    [Fact]
    public void Jma_IterativeCorrections_RestoreToOriginalState()
    {
        var jma = new Jma(10);
        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);

        // Feed 20 new values (enough to fill buffer and stabilize)
        TValue lastInput = default;
        for (int i = 0; i < 20; i++)
        {
            var bar = gbm.Next(isNew: true);
            lastInput = new TValue(bar.Time, bar.Close);
            jma.Update(lastInput, isNew: true);
        }

        // Remember JMA state
        double jmaAfter = jma.Last.Value;

        // Generate 5 corrections with isNew=false (different values)
        for (int i = 0; i < 5; i++)
        {
            var bar = gbm.Next(isNew: false);
            jma.Update(new TValue(bar.Time, bar.Close), isNew: false);
        }

        // Feed the remembered last input again with isNew=false
        TValue finalJma = jma.Update(lastInput, isNew: false);

        // JMA should match the original state
        Assert.Equal(jmaAfter, finalJma.Value, 1e-10);
    }

    [Fact]
    public void Jma_NaN_Input_UsesLastValidValue()
    {
        var jma = new Jma(10);

        // Feed some valid values
        jma.Update(new TValue(DateTime.UtcNow, 100));
        jma.Update(new TValue(DateTime.UtcNow, 110));

        // Feed NaN - should use last valid value (110)
        var resultAfterNaN = jma.Update(new TValue(DateTime.UtcNow, double.NaN));

        // Result should be finite (not NaN)
        Assert.True(double.IsFinite(resultAfterNaN.Value));
        Assert.NotEqual(0, resultAfterNaN.Value);
    }

    [Fact]
    public void Jma_SpanCalc_MatchesTSeriesCalc()
    {
        var series = new TSeries();
        double[] source = new double[100];
        double[] output = new double[100];

        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1, seed: 42);
        for (int i = 0; i < 100; i++)
        {
            var bar = gbm.Next(isNew: true);
            source[i] = bar.Close;
            series.Add(bar.Time, bar.Close);
        }

        // Calculate with TSeries API
        var tseriesResult = Jma.Batch(series, 10);

        // Calculate with Span API
        Jma.Batch(source.AsSpan(), output.AsSpan(), 10);

        // Compare results
        for (int i = 0; i < 100; i++)
        {
            Assert.Equal(tseriesResult[i].Value, output[i], 1e-10);
        }
    }

    [Fact]
    public void Jma_AllModes_ProduceSameResult()
    {
        // Arrange
        const int period = 10;
        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
        var bars = gbm.Fetch(1000, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
        var series = bars.Close;

        // 1. Batch Mode
        var batchSeries = Jma.Batch(series, period);
        double expected = batchSeries.Last.Value;

        // 2. Span Mode
        var tValues = series.Values.ToArray();
        var spanInput = new ReadOnlySpan<double>(tValues);
        var spanOutput = new double[tValues.Length];
        Jma.Batch(spanInput, spanOutput, period);
        double spanResult = spanOutput[^1];

        // 3. Streaming Mode
        var streamingInd = new Jma(period);
        for (int i = 0; i < series.Count; i++)
        {
            streamingInd.Update(series[i]);
        }
        double streamingResult = streamingInd.Last.Value;

        // 4. Eventing Mode
        var pubSource = new TSeries();
        var eventingInd = new Jma(pubSource, period);
        for (int i = 0; i < series.Count; i++)
        {
            pubSource.Add(series[i]);
        }
        double eventingResult = eventingInd.Last.Value;

        // Assert
        Assert.Equal(expected, spanResult, precision: 9);
        Assert.Equal(expected, streamingResult, precision: 9);
        Assert.Equal(expected, eventingResult, precision: 9);
    }

    [Fact]
    public void Jma_Phase_AffectsResult()
    {
        var series = new TSeries();
        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1, seed: 42);
        for (int i = 0; i < 100; i++)
        {
            var bar = gbm.Next(isNew: true);
            series.Add(bar.Time, bar.Close);
        }

        var jmaPhase0 = Jma.Batch(series, 10, phase: 0);
        var jmaPhase100 = Jma.Batch(series, 10, phase: 100);
        var jmaPhaseMinus100 = Jma.Batch(series, 10, phase: -100);

        Assert.NotEqual(jmaPhase0.Last.Value, jmaPhase100.Last.Value);
        Assert.NotEqual(jmaPhase0.Last.Value, jmaPhaseMinus100.Last.Value);
    }

    [Fact]
    public void Jma_Power_RemovedFromApi()
    {
        // Power parameter was removed — it was never used in calculation.
        // Verify the 2-parameter Batch still works correctly.
        var series = new TSeries();
        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1, seed: 42);
        for (int i = 0; i < 100; i++)
        {
            var bar = gbm.Next(isNew: true);
            series.Add(bar.Time, bar.Close);
        }

        var result = Jma.Batch(series, 10);
        Assert.True(double.IsFinite(result.Last.Value));
    }

    [Fact]
    public void Jma_Period_AffectsResult()
    {
        // Verify that different periods produce meaningfully different outputs
        var series = new TSeries();
        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1, seed: 42);
        for (int i = 0; i < 500; i++)
        {
            var bar = gbm.Next(isNew: true);
            series.Add(bar.Time, bar.Close);
        }

        // --- TSeries Batch mode ---
        var jma7 = Jma.Batch(series, 7);
        var jma14 = Jma.Batch(series, 14);
        var jma50 = Jma.Batch(series, 50);
        var jma100 = Jma.Batch(series, 100);

        // Last values must all differ
        Assert.NotEqual(jma7.Last.Value, jma14.Last.Value);
        Assert.NotEqual(jma14.Last.Value, jma50.Last.Value);
        Assert.NotEqual(jma50.Last.Value, jma100.Last.Value);

        // Longer period = smoother = values closer to mean (less extreme)
        // Verify at least some interior values differ (not just the last)
        int midIdx = series.Count / 2;
        Assert.NotEqual(jma7[midIdx].Value, jma50[midIdx].Value);
        Assert.NotEqual(jma14[midIdx].Value, jma100[midIdx].Value);

        // --- Span Batch mode ---
        double[] source = series.Values.ToArray();
        double[] out7 = new double[source.Length];
        double[] out14 = new double[source.Length];
        double[] out50 = new double[source.Length];

        Jma.Batch(source.AsSpan(), out7.AsSpan(), 7);
        Jma.Batch(source.AsSpan(), out14.AsSpan(), 14);
        Jma.Batch(source.AsSpan(), out50.AsSpan(), 50);

        Assert.NotEqual(out7[^1], out14[^1]);
        Assert.NotEqual(out14[^1], out50[^1]);

        // Span results must match TSeries results
        Assert.Equal(jma7.Last.Value, out7[^1], 1e-10);
        Assert.Equal(jma14.Last.Value, out14[^1], 1e-10);
        Assert.Equal(jma50.Last.Value, out50[^1], 1e-10);

        // --- Streaming mode ---
        var stream7 = new Jma(7);
        var stream50 = new Jma(50);
        for (int i = 0; i < series.Count; i++)
        {
            stream7.Update(series[i]);
            stream50.Update(series[i]);
        }
        Assert.NotEqual(stream7.Last.Value, stream50.Last.Value);
        Assert.Equal(jma7.Last.Value, stream7.Last.Value, 1e-10);
        Assert.Equal(jma50.Last.Value, stream50.Last.Value, 1e-10);
    }

    [Fact]
    public void Jma_SpanCalc_HandlesNaN()
    {
        double[] source = [100, 110, double.NaN, 120, 130];
        double[] output = new double[5];

        Jma.Batch(source.AsSpan(), output.AsSpan(), 3);

        foreach (var val in output)
        {
            Assert.True(double.IsFinite(val));
        }
    }

    [Fact]
    public void Jma_BatchUpdate_ThenStreamingUpdate_IsNewFalse_Works()
    {
        // This test verifies the fix for the state synchronization issue
        // where _p_state and buffers weren't updated after batch Update(TSeries)
        var jma = new Jma(10);
        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1, seed: 42);

        // Create a batch series with enough bars to reach warmup (203 for JMA(10))
        int warmupBars = jma.WarmupPeriod + 50;
        var series = new TSeries();
        for (int i = 0; i < warmupBars; i++)
        {
            var bar = gbm.Next(isNew: true);
            series.Add(bar.Time, bar.Close);
        }

        // Process batch - this should update _state, _p_state, and buffer snapshots
        jma.Update(series);

        // Now do a streaming update with isNew=true (new bar)
        var bar51 = gbm.Next(isNew: true);
        jma.Update(new TValue(bar51.Time, bar51.Close), isNew: true);

        // Do several corrections with isNew=false
        for (int i = 0; i < 3; i++)
        {
            var correction = gbm.Next(isNew: false);
            jma.Update(new TValue(correction.Time, correction.Close), isNew: false);
        }

        // Feed the original bar51 value again with isNew=false
        // It should restore to the state after bar51
        var restoredResult = jma.Update(new TValue(bar51.Time, bar51.Close), isNew: false);

        // The key test: After batch processing, we should be able to advance to a new bar
        // and then do corrections without errors. Before the fix, this would fail because
        // _p_state had stale data from before the batch processing.
        Assert.True(double.IsFinite(restoredResult.Value));
        Assert.True(jma.IsHot);
    }
}