// Licensed under BUSL-1.1. Copyright (C) 2026 StellaOps Contributors.

using System.Collections.Immutable;
using FluentAssertions;
using Xunit;

namespace StellaOps.BinaryIndex.Diff.Tests.Unit;

[Trait("Category", "Unit")]
public sealed class PatchDiffModelTests
{
    [Fact]
    public void PatchDiffResult_NoPatchDetected_CreatesCorrectResult()
    {
        // Arrange
        var goldenSetId = "CVE-2024-1234";
        var goldenSetDigest = "sha256:abcd1234";
        var binaryDigest = "sha256:same1234";
        var comparedAt = DateTimeOffset.UtcNow;
        var duration = TimeSpan.FromMilliseconds(100);
        var options = DiffOptions.Default;

        // Act
        var result = PatchDiffResult.NoPatchDetected(
            goldenSetId, goldenSetDigest, binaryDigest,
            comparedAt, duration, options);

        // Assert
        result.GoldenSetId.Should().Be(goldenSetId);
        result.Verdict.Should().Be(PatchVerdict.NoPatchDetected);
        result.Confidence.Should().Be(1.0m);
        result.PreBinaryDigest.Should().Be(binaryDigest);
        result.PostBinaryDigest.Should().Be(binaryDigest);
        result.Evidence.Should().HaveCount(1);
        result.Evidence[0].Type.Should().Be(DiffEvidenceType.IdenticalBinaries);
    }

    [Theory]
    [InlineData(PatchVerdict.Fixed)]
    [InlineData(PatchVerdict.PartialFix)]
    [InlineData(PatchVerdict.StillVulnerable)]
    [InlineData(PatchVerdict.Inconclusive)]
    [InlineData(PatchVerdict.NoPatchDetected)]
    public void PatchVerdict_AllValuesAreDefined(PatchVerdict verdict)
    {
        // Assert
        Enum.IsDefined(verdict).Should().BeTrue();
    }

    [Fact]
    public void FunctionDiffResult_FunctionRemoved_CreatesCorrectResult()
    {
        // Act
        var result = FunctionDiffResult.FunctionRemoved("vulnerable_func");

        // Assert
        result.FunctionName.Should().Be("vulnerable_func");
        result.PreStatus.Should().Be(FunctionStatus.Present);
        result.PostStatus.Should().Be(FunctionStatus.Absent);
        result.Verdict.Should().Be(FunctionPatchVerdict.FunctionRemoved);
    }

    [Fact]
    public void FunctionDiffResult_NotFound_CreatesCorrectResult()
    {
        // Act
        var result = FunctionDiffResult.NotFound("missing_func");

        // Assert
        result.FunctionName.Should().Be("missing_func");
        result.PreStatus.Should().Be(FunctionStatus.Absent);
        result.PostStatus.Should().Be(FunctionStatus.Absent);
        result.Verdict.Should().Be(FunctionPatchVerdict.Inconclusive);
    }

    [Fact]
    public void CfgDiffResult_StructureChanged_DetectsChange()
    {
        // Arrange
        var diff = new CfgDiffResult
        {
            PreCfgHash = "hash1",
            PostCfgHash = "hash2",
            PreBlockCount = 5,
            PostBlockCount = 6,
            PreEdgeCount = 7,
            PostEdgeCount = 9
        };

        // Assert
        diff.StructureChanged.Should().BeTrue();
        diff.BlockCountDelta.Should().Be(1);
        diff.EdgeCountDelta.Should().Be(2);
    }

    [Fact]
    public void CfgDiffResult_NoStructureChange_WhenHashesMatch()
    {
        // Arrange
        var diff = new CfgDiffResult
        {
            PreCfgHash = "samehash",
            PostCfgHash = "samehash",
            PreBlockCount = 5,
            PostBlockCount = 5,
            PreEdgeCount = 7,
            PostEdgeCount = 7
        };

        // Assert
        diff.StructureChanged.Should().BeFalse();
        diff.BlockCountDelta.Should().Be(0);
        diff.EdgeCountDelta.Should().Be(0);
    }
}

[Trait("Category", "Unit")]
public sealed class VulnerableEdgeDiffTests
{
    [Fact]
    public void Compute_AllEdgesRemoved_SetsFlag()
    {
        // Arrange
        var preEdges = ImmutableArray.Create("bb0->bb1", "bb1->bb2");
        var postEdges = ImmutableArray<string>.Empty;

        // Act
        var diff = VulnerableEdgeDiff.Compute(preEdges, postEdges);

        // Assert
        diff.AllVulnerableEdgesRemoved.Should().BeTrue();
        diff.EdgesRemoved.Should().HaveCount(2);
        diff.EdgesAdded.Should().BeEmpty();
    }

    [Fact]
    public void Compute_SomeEdgesRemoved_SetsFlag()
    {
        // Arrange
        var preEdges = ImmutableArray.Create("bb0->bb1", "bb1->bb2");
        var postEdges = ImmutableArray.Create("bb0->bb1");

        // Act
        var diff = VulnerableEdgeDiff.Compute(preEdges, postEdges);

        // Assert
        diff.AllVulnerableEdgesRemoved.Should().BeFalse();
        diff.SomeVulnerableEdgesRemoved.Should().BeTrue();
        diff.EdgesRemoved.Should().Contain("bb1->bb2");
    }

    [Fact]
    public void Compute_NoChange_NoEdgesRemovedOrAdded()
    {
        // Arrange
        var edges = ImmutableArray.Create("bb0->bb1", "bb1->bb2");

        // Act
        var diff = VulnerableEdgeDiff.Compute(edges, edges);

        // Assert
        diff.NoChange.Should().BeTrue();
        diff.EdgesRemoved.Should().BeEmpty();
        diff.EdgesAdded.Should().BeEmpty();
    }

    [Fact]
    public void Compute_EdgesAdded_TracksNewEdges()
    {
        // Arrange
        var preEdges = ImmutableArray.Create("bb0->bb1");
        var postEdges = ImmutableArray.Create("bb0->bb1", "bb1->bb3");

        // Act
        var diff = VulnerableEdgeDiff.Compute(preEdges, postEdges);

        // Assert
        diff.EdgesAdded.Should().Contain("bb1->bb3");
        diff.AllVulnerableEdgesRemoved.Should().BeFalse();
    }

    [Fact]
    public void Empty_ReturnsEmptyDiff()
    {
        // Act
        var empty = VulnerableEdgeDiff.Empty;

        // Assert
        empty.EdgesInPre.Should().BeEmpty();
        empty.EdgesInPost.Should().BeEmpty();
        empty.EdgesRemoved.Should().BeEmpty();
        empty.EdgesAdded.Should().BeEmpty();
    }
}

[Trait("Category", "Unit")]
public sealed class SinkReachabilityDiffTests
{
    [Fact]
    public void Compute_AllSinksUnreachable_SetsFlag()
    {
        // Arrange
        var preSinks = ImmutableArray.Create("memcpy", "strcpy");
        var postSinks = ImmutableArray<string>.Empty;

        // Act
        var diff = SinkReachabilityDiff.Compute(preSinks, postSinks);

        // Assert
        diff.AllSinksUnreachable.Should().BeTrue();
        diff.SinksMadeUnreachable.Should().HaveCount(2);
        diff.SinksStillReachable.Should().BeEmpty();
    }

    [Fact]
    public void Compute_SomeSinksUnreachable_SetsFlag()
    {
        // Arrange
        var preSinks = ImmutableArray.Create("memcpy", "strcpy");
        var postSinks = ImmutableArray.Create("memcpy");

        // Act
        var diff = SinkReachabilityDiff.Compute(preSinks, postSinks);

        // Assert
        diff.AllSinksUnreachable.Should().BeFalse();
        diff.SomeSinksUnreachable.Should().BeTrue();
        diff.SinksMadeUnreachable.Should().Contain("strcpy");
        diff.SinksStillReachable.Should().Contain("memcpy");
    }

    [Fact]
    public void Empty_ReturnsEmptyDiff()
    {
        // Act
        var empty = SinkReachabilityDiff.Empty;

        // Assert
        empty.SinksReachableInPre.Should().BeEmpty();
        empty.SinksReachableInPost.Should().BeEmpty();
        empty.SinksMadeUnreachable.Should().BeEmpty();
        empty.SinksStillReachable.Should().BeEmpty();
    }
}