using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Configs;
using Just.PreciseMath.PerformanceComparison.Reference;

namespace Just.PreciseMath.PerformanceComparison;

/// <summary>
/// Compares the four arithmetic operators on the same ordinary finite operands across
/// binary64, the <c>Just.PreciseMath</c> double-double, and the blog reference
/// implementation. Every category measures one operator, and its binary64 method is
/// the baseline, so the ratio columns read as "times the cost of a double".
/// </summary>
/// <remarks>
/// Operands are independent array elements, so the measurements include loads, stores,
/// and loop overhead on purpose; input construction, conversion, and fixture validation
/// stay outside the timed methods.
/// </remarks>
[MemoryDiagnoser]
[GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByCategory)]
[CategoriesColumn]
public class ArithmeticComparisonBenchmarks
{
    private double[] _doubleLeft = [];
    private double[] _doubleRight = [];
    private DoubleDouble[] _left = [];
    private DoubleDouble[] _right = [];
    private DoubleDoubleSample[] _sampleLeft = [];
    private DoubleDoubleSample[] _sampleRight = [];
    private readonly double[] _doubleResults = new double[PerformanceInputs.Count];
    private readonly DoubleDouble[] _results = new DoubleDouble[PerformanceInputs.Count];
    private readonly DoubleDoubleSample[] _sampleResults = new DoubleDoubleSample[PerformanceInputs.Count];

    [GlobalSetup]
    public void Setup()
    {
        PerformanceInputs inputs = PerformanceInputs.Create();
        _doubleLeft = inputs.DoubleLeft;
        _doubleRight = inputs.DoubleRight;
        _left = inputs.Left;
        _right = inputs.Right;
        _sampleLeft = inputs.SampleLeft;
        _sampleRight = inputs.SampleRight;
    }

    [Benchmark(Baseline = true, OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Addition")]
    public double[] DoubleAdd()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _doubleResults[i] = _doubleLeft[i] + _doubleRight[i];
        }
        return _doubleResults;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Addition")]
    public DoubleDouble[] DoubleDoubleAdd()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _results[i] = _left[i] + _right[i];
        }
        return _results;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Addition")]
    public DoubleDoubleSample[] DoubleDoubleSampleAdd()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _sampleResults[i] = _sampleLeft[i] + _sampleRight[i];
        }
        return _sampleResults;
    }

    [Benchmark(Baseline = true, OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Subtraction")]
    public double[] DoubleSubtract()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _doubleResults[i] = _doubleLeft[i] - _doubleRight[i];
        }
        return _doubleResults;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Subtraction")]
    public DoubleDouble[] DoubleDoubleSubtract()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _results[i] = _left[i] - _right[i];
        }
        return _results;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Subtraction")]
    public DoubleDoubleSample[] DoubleDoubleSampleSubtract()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _sampleResults[i] = _sampleLeft[i] - _sampleRight[i];
        }
        return _sampleResults;
    }

    [Benchmark(Baseline = true, OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Multiplication")]
    public double[] DoubleMultiply()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _doubleResults[i] = _doubleLeft[i] * _doubleRight[i];
        }
        return _doubleResults;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Multiplication")]
    public DoubleDouble[] DoubleDoubleMultiply()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _results[i] = _left[i] * _right[i];
        }
        return _results;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Multiplication")]
    public DoubleDoubleSample[] DoubleDoubleSampleMultiply()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _sampleResults[i] = _sampleLeft[i] * _sampleRight[i];
        }
        return _sampleResults;
    }

    [Benchmark(Baseline = true, OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Division")]
    public double[] DoubleDivide()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _doubleResults[i] = _doubleLeft[i] / _doubleRight[i];
        }
        return _doubleResults;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Division")]
    public DoubleDouble[] DoubleDoubleDivide()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _results[i] = _left[i] / _right[i];
        }
        return _results;
    }

    [Benchmark(OperationsPerInvoke = PerformanceInputs.Count), BenchmarkCategory("Division")]
    public DoubleDoubleSample[] DoubleDoubleSampleDivide()
    {
        for (int i = 0; i < PerformanceInputs.Count; i++)
        {
            _sampleResults[i] = _sampleLeft[i] / _sampleRight[i];
        }
        return _sampleResults;
    }
}