using System.Collections.Immutable;
using StellaOps.Concelier.SbomIntegration.Models;
using StellaOps.Scanner.ServiceSecurity;
using StellaOps.Scanner.ServiceSecurity.Analyzers;
using StellaOps.Scanner.ServiceSecurity.Models;
using StellaOps.Scanner.ServiceSecurity.Policy;
using StellaOps.TestKit;
using Xunit;

namespace StellaOps.Scanner.ServiceSecurity.Tests;

public sealed class ServiceSecurityAnalyzerTests
{
    private static readonly TimeProvider FixedTimeProviderInstance =
        new FixedTimeProvider(new DateTimeOffset(2026, 1, 19, 0, 0, 0, TimeSpan.Zero));

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task EndpointSchemeAnalyzer_FlagsInsecureSchemes()
    {
        var service = CreateService(
            "svc-1",
            "api",
            endpoints:
            [
                "http://api.example.com",
                "https://api.example.com",
                "ws://api.example.com",
                "ftp://api.example.com"
            ]);

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new EndpointSchemeAnalyzer(), service);

        Assert.Equal(3, report.Findings.Length);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.InsecureEndpointScheme);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.DeprecatedProtocol);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task AuthenticationAnalyzer_FlagsUnauthenticatedScenarios()
    {
        var service = CreateService(
            "svc-1",
            "billing",
            authenticated: false,
            crossesTrustBoundary: true,
            endpoints: ["https://billing.example.com"],
            data: [Flow(classification: "PII")]);

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new AuthenticationAnalyzer(), service);

        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.UnauthenticatedEndpoint);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.CrossesTrustBoundaryWithoutAuth);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.SensitiveDataExposed);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task TrustBoundaryAnalyzer_BuildsDependencyChains()
    {
        var serviceA = CreateService(
            "svc-a",
            "gateway",
            authenticated: true,
            endpoints: ["https://api.example.com"],
            data: [Flow(destinationRef: "svc-b", classification: "PII")],
            properties: BuildProperties(("x-trust-boundary", "external")));
        var serviceB = CreateService(
            "svc-b",
            "auth",
            authenticated: false,
            properties: BuildProperties(("x-trust-boundary", "internal")));

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new TrustBoundaryAnalyzer(), serviceA, serviceB);

        Assert.NotEmpty(report.DependencyChains);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.CrossesTrustBoundaryWithoutAuth);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task DataFlowAnalyzer_FlagsSensitiveUnencryptedFlows()
    {
        var serviceA = CreateService(
            "svc-a",
            "front",
            authenticated: true,
            data: [Flow(destinationRef: "svc-b", classification: "PII")]);
        var serviceB = CreateService(
            "svc-b",
            "processor",
            authenticated: false,
            endpoints: ["http://processor.internal"]);

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new DataFlowAnalyzer(), serviceA, serviceB);

        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.SensitiveDataExposed);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.UnencryptedDataFlow);
        Assert.NotNull(report.DataFlowGraph);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task RateLimitingAnalyzer_FlagsDisabledRateLimit()
    {
        var service = CreateService(
            "svc-1",
            "api",
            endpoints: ["https://api.example.com"],
            properties: BuildProperties(("x-rate-limited", "false")));

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new RateLimitingAnalyzer(), service);

        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.MissingRateLimiting);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task ServiceVulnerabilityMatcher_FlagsDeprecatedAndAdvisoryMatches()
    {
        var policy = ServiceSecurityPolicyDefaults.Default with
        {
            DeprecatedServices = ImmutableArray.Create(new DeprecatedServicePolicy
            {
                Name = "redis",
                BeforeVersion = "6.0",
                Severity = Severity.High,
                CveId = "CVE-2026-0001",
                Reason = "Pre-6.0 releases are out of support."
            })
        };
        var service = CreateService("svc-redis", "redis", version: "5.0.1");
        var provider = new StubAdvisoryProvider();

        var report = await RunAnalyzer(policy, new ServiceVulnerabilityMatcher(provider), service);

        Assert.Equal(2, report.Findings.Length);
        Assert.All(report.Findings, finding => Assert.Equal(ServiceSecurityFindingType.KnownVulnerableServiceVersion, finding.Type));
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task NestedServiceAnalyzer_DetectsCyclesAndOrphans()
    {
        var serviceA = CreateService(
            "svc-a",
            "alpha",
            data: [Flow(sourceRef: "svc-a", destinationRef: "svc-b", classification: "PII")]);
        var serviceB = CreateService(
            "svc-b",
            "beta",
            data: [Flow(sourceRef: "svc-b", destinationRef: "svc-a", classification: "PII")]);
        var orphan = CreateService("svc-c", "orphan");

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new NestedServiceAnalyzer(), serviceA, serviceB, orphan);

        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.CircularDependency);
        Assert.Contains(report.Findings, finding => finding.Type == ServiceSecurityFindingType.OrphanedService);
        Assert.NotNull(report.Topology);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public async Task Analyzer_SummaryCountsMatchFindings()
    {
        var service = CreateService(
            "svc-1",
            "api",
            authenticated: false,
            endpoints: ["http://api.example.com"]);

        var report = await RunAnalyzer(ServiceSecurityPolicyDefaults.Default, new EndpointSchemeAnalyzer(), new AuthenticationAnalyzer(), service);

        Assert.Equal(report.Findings.Length, report.Summary.TotalFindings);
        Assert.True(report.Summary.FindingsByType.Count >= 2);
    }

    private static async Task<ServiceSecurityReport> RunAnalyzer(
        ServiceSecurityPolicy policy,
        IServiceSecurityCheck check,
        params ParsedService[] services)
    {
        var analyzer = new ServiceSecurityAnalyzer(new[] { check }, FixedTimeProviderInstance);
        return await analyzer.AnalyzeAsync(services, policy);
    }

    private static async Task<ServiceSecurityReport> RunAnalyzer(
        ServiceSecurityPolicy policy,
        IServiceSecurityCheck first,
        IServiceSecurityCheck second,
        params ParsedService[] services)
    {
        var analyzer = new ServiceSecurityAnalyzer(new IServiceSecurityCheck[] { first, second }, FixedTimeProviderInstance);
        return await analyzer.AnalyzeAsync(services, policy);
    }

    private static ParsedService CreateService(
        string bomRef,
        string name,
        bool authenticated = true,
        bool crossesTrustBoundary = false,
        string? version = null,
        string[]? endpoints = null,
        ParsedDataFlow[]? data = null,
        ParsedService[]? nested = null,
        IReadOnlyDictionary<string, string>? properties = null)
    {
        var props = properties is null
            ? ImmutableDictionary<string, string>.Empty
            : ImmutableDictionary.CreateRange(StringComparer.OrdinalIgnoreCase, properties);

        return new ParsedService
        {
            BomRef = bomRef,
            Name = name,
            Version = version,
            Authenticated = authenticated,
            CrossesTrustBoundary = crossesTrustBoundary,
            Endpoints = endpoints?.ToImmutableArray() ?? [],
            Data = data?.ToImmutableArray() ?? [],
            NestedServices = nested?.ToImmutableArray() ?? [],
            Properties = props
        };
    }

    private static ParsedDataFlow Flow(
        string? sourceRef = null,
        string? destinationRef = null,
        string classification = "PII",
        DataFlowDirection direction = DataFlowDirection.Outbound)
    {
        return new ParsedDataFlow
        {
            Direction = direction,
            Classification = classification,
            SourceRef = sourceRef,
            DestinationRef = destinationRef
        };
    }

    private static IReadOnlyDictionary<string, string> BuildProperties(params (string Key, string Value)[] entries)
    {
        var values = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        foreach (var entry in entries)
        {
            values[entry.Key] = entry.Value;
        }

        return values;
    }

    private sealed class StubAdvisoryProvider : IServiceAdvisoryProvider
    {
        public Task<IReadOnlyList<ServiceAdvisoryMatch>> GetMatchesAsync(
            ParsedService service,
            CancellationToken ct = default)
        {
            return Task.FromResult<IReadOnlyList<ServiceAdvisoryMatch>>(new[]
            {
                new ServiceAdvisoryMatch
                {
                    CveId = "CVE-2026-1234",
                    Severity = Severity.High,
                    Description = "Service version is affected."
                }
            });
        }
    }

    private sealed class FixedTimeProvider : TimeProvider
    {
        private readonly DateTimeOffset _fixed;

        public FixedTimeProvider(DateTimeOffset fixedTime)
        {
            _fixed = fixedTime;
        }

        public override DateTimeOffset GetUtcNow() => _fixed;
    }
}