using System;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Threading.Tasks;
using FastRng;
using NUnit.Framework;

namespace FastRngTests.Distributions;

[ExcludeFromCodeCoverage]
public class NormalS02M05
{
    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestNormalDistribution01()
    {
        const float MEAN = 0.5f;
        const float STANDARD_DEVIATION = 0.2f;

        using var rng = new MultiThreadedRng<float>();
        var dist = new FastRng.Distributions.NormalS02M05<float>(rng);
        var stats = new RunningStatistics();
        var fra = new FrequencyAnalysis();

        for (var n = 0; n < 100_000; n++)
        {
            var nextNumber = await dist.NextNumber();
            stats.Push(nextNumber);
            fra.CountThis(nextNumber);
        }

        fra.NormalizeAndPlotEvents(TestContext.WriteLine);
            
        TestContext.WriteLine($"mean={MEAN} vs. {stats.Mean}");
        TestContext.WriteLine($"variance={STANDARD_DEVIATION * STANDARD_DEVIATION} vs {stats.Variance}");
            
        Assert.That(stats.Mean, Is.EqualTo(MEAN).Within(0.01f), "Mean is out of range");
        Assert.That(stats.Variance, Is.EqualTo(STANDARD_DEVIATION*STANDARD_DEVIATION).Within(0.01f), "Variance is out of range");
    }

    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestNormalGeneratorWithRange01()
    {
        using var rng = new MultiThreadedRng<float>();
        var samples = new float[1_000];
        var dist = new FastRng.Distributions.NormalS02M05<float>(rng);
        for (var n = 0; n < samples.Length; n++)
            samples[n] = await dist.NextNumber(-1.0f, 1.0f);
            
        Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(-1.0f), "Min is out of range");
        Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0f), "Max is out of range");
    }
        
    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public async Task TestNormalGeneratorWithRange02()
    {
        using var rng = new MultiThreadedRng<float>();
        var samples = new float[1_000];
        var dist = new FastRng.Distributions.NormalS02M05<float>(rng);
        for (var n = 0; n < samples.Length; n++)
            samples[n] = await dist.NextNumber(0.0f, 1.0f);
            
        Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(0.0f), "Min is out of range");
        Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0f), "Max is out of range");
    }

    [Test]
    [Category(TestCategories.COVER)]
    [Category(TestCategories.NORMAL)]
    public void NoRandomNumberGenerator01()
    {
        Assert.Throws<ArgumentNullException>(() => new FastRng.Distributions.NormalS02M05<float>(null));
    }
}