using System.Collections.Immutable;
using FluentAssertions;
using StellaOps.Policy.Engine.SelectionJoin;
using Xunit;

namespace StellaOps.Policy.Engine.Tests.SelectionJoin;

public sealed class SelectionJoinTests
{
    #region PurlEquivalence Tests

    [Theory]
    [InlineData("pkg:npm/lodash@4.17.21", "pkg:npm/lodash")]
    [InlineData("pkg:maven/org.apache.commons/commons-lang3@3.12.0", "pkg:maven/org.apache.commons/commons-lang3")]
    [InlineData("pkg:pypi/requests@2.28.0", "pkg:pypi/requests")]
    [InlineData("pkg:gem/rails@7.0.0", "pkg:gem/rails")]
    [InlineData("pkg:nuget/Newtonsoft.Json@13.0.1", "pkg:nuget/Newtonsoft.Json")]
    public void ExtractPackageKey_RemovesVersion(string purl, string expectedKey)
    {
        var key = PurlEquivalence.ExtractPackageKey(purl);

        key.Should().Be(expectedKey);
    }

    [Fact]
    public void ExtractPackageKey_HandlesNoVersion()
    {
        var purl = "pkg:npm/lodash";

        var key = PurlEquivalence.ExtractPackageKey(purl);

        key.Should().Be("pkg:npm/lodash");
    }

    [Fact]
    public void ExtractPackageKey_HandlesScopedPackages()
    {
        var purl = "pkg:npm/@scope/package@1.0.0";

        var key = PurlEquivalence.ExtractPackageKey(purl);

        key.Should().Be("pkg:npm/@scope/package");
    }

    [Theory]
    [InlineData("pkg:npm/lodash@4.17.21", "npm")]
    [InlineData("pkg:maven/org.apache/commons@1.0", "maven")]
    [InlineData("pkg:pypi/requests@2.28", "pypi")]
    public void ExtractEcosystem_ReturnsCorrectEcosystem(string purl, string expected)
    {
        var ecosystem = PurlEquivalence.ExtractEcosystem(purl);

        ecosystem.Should().Be(expected);
    }

    [Fact]
    public void ComputeMatchConfidence_ExactMatch_Returns1()
    {
        var confidence = PurlEquivalence.ComputeMatchConfidence(
            "pkg:npm/lodash@4.17.21",
            "pkg:npm/lodash@4.17.21");

        confidence.Should().Be(1.0);
    }

    [Fact]
    public void ComputeMatchConfidence_PackageKeyMatch_Returns08()
    {
        var confidence = PurlEquivalence.ComputeMatchConfidence(
            "pkg:npm/lodash@4.17.21",
            "pkg:npm/lodash@4.17.20");

        confidence.Should().Be(0.8);
    }

    #endregion

    #region PurlEquivalenceTable Tests

    [Fact]
    public void FromGroups_CreatesEquivalentMappings()
    {
        var groups = new[]
        {
            new[] { "pkg:npm/lodash", "pkg:npm/lodash-es" }
        };

        var table = PurlEquivalenceTable.FromGroups(groups);

        table.AreEquivalent("pkg:npm/lodash", "pkg:npm/lodash-es").Should().BeTrue();
        table.GroupCount.Should().Be(1);
    }

    [Fact]
    public void GetCanonical_ReturnsFirstLexicographically()
    {
        var groups = new[]
        {
            new[] { "pkg:npm/b-package", "pkg:npm/a-package" }
        };

        var table = PurlEquivalenceTable.FromGroups(groups);

        // "a-package" is lexicographically first
        table.GetCanonical("pkg:npm/b-package").Should().Be("pkg:npm/a-package");
    }

    [Fact]
    public void GetEquivalents_ReturnsAllEquivalentPurls()
    {
        var groups = new[]
        {
            new[] { "pkg:npm/a", "pkg:npm/b", "pkg:npm/c" }
        };

        var table = PurlEquivalenceTable.FromGroups(groups);
        var equivalents = table.GetEquivalents("pkg:npm/b");

        equivalents.Should().HaveCount(3);
        equivalents.Should().Contain("pkg:npm/a");
        equivalents.Should().Contain("pkg:npm/b");
        equivalents.Should().Contain("pkg:npm/c");
    }

    [Fact]
    public void Empty_HasNoMappings()
    {
        var table = PurlEquivalenceTable.Empty;

        table.GroupCount.Should().Be(0);
        table.TotalEntries.Should().Be(0);
        table.AreEquivalent("pkg:npm/a", "pkg:npm/b").Should().BeFalse();
    }

    #endregion

    #region SelectionJoinService Tests

    [Fact]
    public void ResolveTuples_MatchesByExactPurl()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput(
                    Purl: "pkg:npm/lodash@4.17.21",
                    Name: "lodash",
                    Version: "4.17.21",
                    Ecosystem: "npm",
                    Metadata: ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput(
                    AdvisoryId: "GHSA-test-001",
                    Source: "github",
                    Purls: ["pkg:npm/lodash@4.17.21"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-12345"],
                    Confidence: 1.0)
            ],
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Tuples.Should().ContainSingle();
        result.Tuples[0].MatchType.Should().Be(SelectionMatchType.ExactPurl);
        result.Tuples[0].Component.Purl.Should().Be("pkg:npm/lodash@4.17.21");
        result.Statistics.ExactPurlMatches.Should().Be(1);
    }

    [Fact]
    public void ResolveTuples_MatchesByPackageKey()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput("pkg:npm/lodash@4.17.21", "lodash", "4.17.21", "npm",
                    ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput("GHSA-test-001", "github",
                    Purls: ["pkg:npm/lodash@4.17.20"], // Different version
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-12345"],
                    Confidence: 1.0)
            ],
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Tuples.Should().ContainSingle();
        result.Tuples[0].MatchType.Should().Be(SelectionMatchType.PackageKeyMatch);
    }

    [Fact]
    public void ResolveTuples_AppliesVexOverlay()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput("pkg:npm/lodash@4.17.21", "lodash", "4.17.21", "npm",
                    ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput("GHSA-test-001", "github",
                    Purls: ["pkg:npm/lodash@4.17.21"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-12345"],
                    Confidence: 1.0)
            ],
            VexLinksets: [
                new VexLinksetInput("vex-1", "CVE-2021-12345", "pkg:npm/lodash@4.17.21",
                    "not_affected", "vulnerable_code_not_in_execute_path", VexConfidenceLevel.High)
            ],
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Tuples.Should().ContainSingle();
        result.Tuples[0].Vex.Should().NotBeNull();
        result.Tuples[0].Vex!.Status.Should().Be("not_affected");
        result.Statistics.VexOverlays.Should().Be(1);
    }

    [Fact]
    public void ResolveTuples_ProducesDeterministicOrdering()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput("pkg:npm/z-package@1.0.0", "z", "1.0.0", "npm",
                    ImmutableDictionary<string, string>.Empty),
                new SbomComponentInput("pkg:npm/a-package@1.0.0", "a", "1.0.0", "npm",
                    ImmutableDictionary<string, string>.Empty),
                new SbomComponentInput("pkg:npm/m-package@1.0.0", "m", "1.0.0", "npm",
                    ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput("ADV-001", "test",
                    Purls: ["pkg:npm/z-package", "pkg:npm/a-package", "pkg:npm/m-package"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-001"],
                    Confidence: 1.0)
            ],
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        // Should be sorted by component PURL
        result.Tuples.Should().HaveCount(3);
        result.Tuples[0].Component.Purl.Should().Be("pkg:npm/a-package@1.0.0");
        result.Tuples[1].Component.Purl.Should().Be("pkg:npm/m-package@1.0.0");
        result.Tuples[2].Component.Purl.Should().Be("pkg:npm/z-package@1.0.0");
    }

    [Fact]
    public void ResolveTuples_HandlesMultipleAdvisories()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput("pkg:npm/lodash@4.17.21", "lodash", "4.17.21", "npm",
                    ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput("ADV-001", "test",
                    Purls: ["pkg:npm/lodash@4.17.21"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-001"],
                    Confidence: 1.0),
                new AdvisoryLinksetInput("ADV-002", "test",
                    Purls: ["pkg:npm/lodash@4.17.21"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-2021-002"],
                    Confidence: 1.0)
            ],
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Tuples.Should().HaveCount(2);
        result.Tuples.Should().Contain(t => t.Advisory.AdvisoryId == "ADV-001");
        result.Tuples.Should().Contain(t => t.Advisory.AdvisoryId == "ADV-002");
    }

    [Fact]
    public void ResolveTuples_ReturnsStatistics()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: [
                new SbomComponentInput("pkg:npm/a@1.0.0", "a", "1.0.0", "npm",
                    ImmutableDictionary<string, string>.Empty),
                new SbomComponentInput("pkg:npm/b@1.0.0", "b", "1.0.0", "npm",
                    ImmutableDictionary<string, string>.Empty)
            ],
            Advisories: [
                new AdvisoryLinksetInput("ADV-001", "test",
                    Purls: ["pkg:npm/a"],
                    Cpes: ImmutableArray<string>.Empty,
                    Aliases: ["CVE-001"],
                    Confidence: 1.0)
            ],
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Statistics.TotalComponents.Should().Be(2);
        result.Statistics.TotalAdvisories.Should().Be(1);
        result.Statistics.MatchedTuples.Should().Be(1);
        result.UnmatchedComponents.Should().ContainSingle(c => c.Purl == "pkg:npm/b@1.0.0");
    }

    [Fact]
    public void ResolveTuples_HandlesEmptyInput()
    {
        var service = new SelectionJoinService();
        var input = new SelectionJoinBatchInput(
            TenantId: "test-tenant",
            BatchId: "batch-1",
            Components: ImmutableArray<SbomComponentInput>.Empty,
            Advisories: ImmutableArray<AdvisoryLinksetInput>.Empty,
            VexLinksets: ImmutableArray<VexLinksetInput>.Empty,
            EquivalenceTable: null,
            Options: new SelectionJoinOptions());

        var result = service.ResolveTuples(input);

        result.Tuples.Should().BeEmpty();
        result.Statistics.TotalComponents.Should().Be(0);
    }

    #endregion

    #region SelectionJoinTuple Tests

    [Fact]
    public void CreateTupleId_IsDeterministic()
    {
        var id1 = SelectionJoinTuple.CreateTupleId("tenant1", "pkg:npm/lodash@4.17.21", "CVE-2021-12345");
        var id2 = SelectionJoinTuple.CreateTupleId("tenant1", "pkg:npm/lodash@4.17.21", "CVE-2021-12345");

        id1.Should().Be(id2);
        id1.Should().StartWith("tuple:sha256:");
    }

    [Fact]
    public void CreateTupleId_NormalizesInput()
    {
        var id1 = SelectionJoinTuple.CreateTupleId("TENANT1", "PKG:NPM/LODASH@4.17.21", "CVE-2021-12345");
        var id2 = SelectionJoinTuple.CreateTupleId("tenant1", "pkg:npm/lodash@4.17.21", "CVE-2021-12345");

        id1.Should().Be(id2);
    }

    #endregion
}