using FluentAssertions;
using NSubstitute;
using StellaOps.BinaryIndex.Validation;
using StellaOps.BinaryIndex.Validation.Abstractions;
using Xunit;

namespace StellaOps.BinaryIndex.Validation.Tests;

/// <summary>
/// Tests for MismatchAnalyzer.
/// </summary>
public class MismatchAnalyzerTests
{
    private readonly IMismatchCauseInferrer _causeInferrer;
    private readonly MismatchAnalyzer _sut;

    public MismatchAnalyzerTests()
    {
        _causeInferrer = Substitute.For<IMismatchCauseInferrer>();
        _sut = new MismatchAnalyzer(_causeInferrer);
    }

    [Fact]
    public async Task AnalyzeAsync_WithEmptyList_ReturnsEmptyBuckets()
    {
        // Arrange
        var mismatches = new List<MatchResult>();

        // Act
        var analysis = await _sut.AnalyzeAsync(mismatches, maxExamplesPerBucket: 5);

        // Assert
        analysis.Buckets.Should().BeEmpty();
        analysis.TotalMismatches.Should().Be(0);
        analysis.DominantCause.Should().BeNull();
    }

    [Fact]
    public async Task AnalyzeAsync_GroupsMismatchesByCause()
    {
        // Arrange
        var mismatches = new List<MatchResult>
        {
            CreateMismatch("func1@@GLIBC_2.17"),
            CreateMismatch("func2@@GLIBC_2.34"),
            CreateMismatch("small_func", size: 20)
        };

        _causeInferrer.InferCauseAsync(Arg.Any<MatchResult>(), Arg.Any<CancellationToken>())
            .Returns(callInfo =>
            {
                var mismatch = callInfo.Arg<MatchResult>();
                if (mismatch.SourceFunction.Name.Contains("@@"))
                    return (MismatchCause.SymbolVersioning, 0.9);
                return (MismatchCause.Inlining, 0.6);
            });

        // Act
        var analysis = await _sut.AnalyzeAsync(mismatches, maxExamplesPerBucket: 5);

        // Assert
        analysis.Buckets.Should().HaveCount(2);
        analysis.TotalMismatches.Should().Be(3);
        analysis.Buckets[MismatchCause.SymbolVersioning].Count.Should().Be(2);
        analysis.Buckets[MismatchCause.Inlining].Count.Should().Be(1);
    }

    [Fact]
    public async Task AnalyzeAsync_DominantCause_IsHighestCount()
    {
        // Arrange
        var mismatches = Enumerable.Range(0, 10)
            .Select(i => CreateMismatch($"func_{i}"))
            .ToList();

        _causeInferrer.InferCauseAsync(Arg.Any<MatchResult>(), Arg.Any<CancellationToken>())
            .Returns(callInfo =>
            {
                var index = int.Parse(callInfo.Arg<MatchResult>().SourceFunction.Name.Split('_')[1]);
                return index < 7 
                    ? (MismatchCause.OptimizationLevel, 0.8) 
                    : (MismatchCause.CompilerVersion, 0.7);
            });

        // Act
        var analysis = await _sut.AnalyzeAsync(mismatches, maxExamplesPerBucket: 3);

        // Assert
        analysis.DominantCause.Should().Be(MismatchCause.OptimizationLevel);
        analysis.Buckets[MismatchCause.OptimizationLevel].Count.Should().Be(7);
        analysis.Buckets[MismatchCause.CompilerVersion].Count.Should().Be(3);
    }

    [Fact]
    public async Task AnalyzeAsync_LimitsExamplesPerBucket()
    {
        // Arrange
        var mismatches = Enumerable.Range(0, 20)
            .Select(i => CreateMismatch($"func_{i}"))
            .ToList();

        _causeInferrer.InferCauseAsync(Arg.Any<MatchResult>(), Arg.Any<CancellationToken>())
            .Returns((MismatchCause.Unknown, 0.5));

        // Act
        var analysis = await _sut.AnalyzeAsync(mismatches, maxExamplesPerBucket: 5);

        // Assert
        analysis.Buckets[MismatchCause.Unknown].Examples.Should().HaveCount(5);
        analysis.Buckets[MismatchCause.Unknown].Count.Should().Be(20);
    }

    [Fact]
    public async Task AnalyzeAsync_CalculatesPercentages()
    {
        // Arrange
        var mismatches = Enumerable.Range(0, 100)
            .Select(i => CreateMismatch($"func_{i}"))
            .ToList();

        _causeInferrer.InferCauseAsync(Arg.Any<MatchResult>(), Arg.Any<CancellationToken>())
            .Returns(callInfo =>
            {
                var index = int.Parse(callInfo.Arg<MatchResult>().SourceFunction.Name.Split('_')[1]);
                return index < 60 
                    ? (MismatchCause.Inlining, 0.8) 
                    : (MismatchCause.LinkTimeOptimization, 0.7);
            });

        // Act
        var analysis = await _sut.AnalyzeAsync(mismatches, maxExamplesPerBucket: 5);

        // Assert
        analysis.Buckets[MismatchCause.Inlining].Percentage.Should().BeApproximately(60, 0.1);
        analysis.Buckets[MismatchCause.LinkTimeOptimization].Percentage.Should().BeApproximately(40, 0.1);
    }

    private static MatchResult CreateMismatch(string functionName, ulong? size = null)
    {
        return new MatchResult
        {
            Id = Guid.NewGuid(),
            RunId = Guid.NewGuid(),
            SecurityPairId = Guid.NewGuid(),
            SourceFunction = new FunctionIdentifier
            {
                Name = functionName,
                Address = 0x1000,
                Size = size,
                BuildId = "abc123",
                BinaryName = "test.so"
            },
            ExpectedTarget = new FunctionIdentifier
            {
                Name = functionName.Replace("@@GLIBC_2.17", "").Replace("@@GLIBC_2.34", ""),
                Address = 0x2000,
                BuildId = "def456",
                BinaryName = "test.so"
            },
            Outcome = MatchOutcome.FalseNegative
        };
    }
}

/// <summary>
/// Tests for HeuristicMismatchCauseInferrer.
/// </summary>
public class HeuristicMismatchCauseInferrerTests
{
    private readonly HeuristicMismatchCauseInferrer _sut = new();

    [Theory]
    [InlineData("printf@@GLIBC_2.17", MismatchCause.SymbolVersioning)]
    [InlineData("malloc@@GLIBC_2.34", MismatchCause.SymbolVersioning)]
    public async Task InferCauseAsync_SymbolVersioning_DetectedCorrectly(string name, MismatchCause expected)
    {
        // Arrange
        var mismatch = CreateMismatch(name);

        // Act
        var (cause, confidence) = await _sut.InferCauseAsync(mismatch);

        // Assert
        cause.Should().Be(expected);
        confidence.Should().BeGreaterThan(0.8);
    }

    [Theory]
    [InlineData("small_func", 20, MismatchCause.Inlining)]
    [InlineData("tiny_func", 10, MismatchCause.Inlining)]
    public async Task InferCauseAsync_SmallFunction_InfersInlining(string name, ulong size, MismatchCause expected)
    {
        // Arrange
        var mismatch = CreateMismatch(name, size);

        // Act
        var (cause, _) = await _sut.InferCauseAsync(mismatch);

        // Assert
        cause.Should().Be(expected);
    }

    [Theory]
    [InlineData("func.cold", MismatchCause.FunctionSplit)]
    [InlineData("func.isra.0", MismatchCause.FunctionSplit)]
    [InlineData("func.part.1", MismatchCause.FunctionSplit)]
    public async Task InferCauseAsync_SplitFunction_DetectedCorrectly(string name, MismatchCause expected)
    {
        // Arrange
        var mismatch = CreateMismatch(name, 500);

        // Act
        var (cause, confidence) = await _sut.InferCauseAsync(mismatch);

        // Assert
        cause.Should().Be(expected);
        confidence.Should().BeGreaterThan(0.7);
    }

    [Theory]
    [InlineData("__asan_load8", MismatchCause.SanitizerInstrumentation)]
    [InlineData("__tsan_write4", MismatchCause.SanitizerInstrumentation)]
    [InlineData("__ubsan_handle_divrem_overflow", MismatchCause.SanitizerInstrumentation)]
    public async Task InferCauseAsync_Sanitizer_DetectedCorrectly(string name, MismatchCause expected)
    {
        // Arrange
        var mismatch = CreateMismatch(name, 100);

        // Act
        var (cause, confidence) = await _sut.InferCauseAsync(mismatch);

        // Assert
        cause.Should().Be(expected);
        confidence.Should().BeGreaterThan(0.9);
    }

    [Fact]
    public async Task InferCauseAsync_UnknownPattern_ReturnsUnknown()
    {
        // Arrange
        var mismatch = CreateMismatch("normal_large_function", 1000);

        // Act
        var (cause, confidence) = await _sut.InferCauseAsync(mismatch);

        // Assert
        cause.Should().Be(MismatchCause.Unknown);
        confidence.Should().BeLessThan(0.5);
    }

    private static MatchResult CreateMismatch(string name, ulong? size = null)
    {
        return new MatchResult
        {
            Id = Guid.NewGuid(),
            RunId = Guid.NewGuid(),
            SecurityPairId = Guid.NewGuid(),
            SourceFunction = new FunctionIdentifier
            {
                Name = name,
                Address = 0x1000,
                Size = size,
                BuildId = "abc123",
                BinaryName = "test.so"
            },
            ExpectedTarget = new FunctionIdentifier
            {
                Name = name,
                Address = 0x2000,
                BuildId = "def456",
                BinaryName = "test.so"
            },
            Outcome = MatchOutcome.FalseNegative
        };
    }
}