// <copyright file="ScannerConfigDiffTests.cs" company="StellaOps">
// Copyright (c) StellaOps. Licensed under AGPL-3.0-or-later.
// </copyright>
// Sprint: SPRINT_20260105_002_005_TEST_cross_cutting
// Task: CCUT-022

using System.Collections.Immutable;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using StellaOps.TestKit;
using StellaOps.Testing.ConfigDiff;
using Xunit;

namespace StellaOps.Scanner.ConfigDiff.Tests;

/// <summary>
/// Config-diff tests for the Scanner module.
/// Verifies that configuration changes produce only expected behavioral deltas.
/// </summary>
[Trait("Category", TestCategories.ConfigDiff)]
[Trait("Category", TestCategories.Integration)]
[Trait("BlastRadius", TestCategories.BlastRadius.Scanning)]
public class ScannerConfigDiffTests : ConfigDiffTestBase
{
    /// <summary>
    /// Initializes a new instance of the <see cref="ScannerConfigDiffTests"/> class.
    /// </summary>
    public ScannerConfigDiffTests()
        : base(
            new ConfigDiffTestConfig(StrictMode: true),
            NullLogger.Instance)
    {
    }

    /// <summary>
    /// Verifies that changing scan depth only affects traversal behavior.
    /// </summary>
    [Fact]
    public async Task ChangingScanDepth_OnlyAffectsTraversal()
    {
        // Arrange
        var baselineConfig = new ScannerTestConfig
        {
            MaxScanDepth = 10,
            EnableReachabilityAnalysis = true,
            MaxConcurrentAnalyzers = 4
        };

        var changedConfig = baselineConfig with
        {
            MaxScanDepth = 20
        };

        // Act
        var result = await TestConfigIsolationAsync(
            baselineConfig,
            changedConfig,
            changedSetting: "MaxScanDepth",
            unrelatedBehaviors:
            [
                async config => await GetReachabilityBehaviorAsync(config),
                async config => await GetConcurrencyBehaviorAsync(config),
                async config => await GetOutputFormatBehaviorAsync(config)
            ]);

        // Assert
        result.IsSuccess.Should().BeTrue(
            because: "changing scan depth should not affect reachability or concurrency");
    }

    /// <summary>
    /// Verifies that enabling reachability analysis produces expected delta.
    /// </summary>
    [Fact]
    public async Task EnablingReachability_ProducesExpectedDelta()
    {
        // Arrange
        var baselineConfig = new ScannerTestConfig { EnableReachabilityAnalysis = false };
        var changedConfig = new ScannerTestConfig { EnableReachabilityAnalysis = true };

        var expectedDelta = new ConfigDelta(
            ChangedBehaviors: ["ReachabilityMode", "ScanDuration", "OutputDetail"],
            BehaviorDeltas:
            [
                new BehaviorDelta("ReachabilityMode", "disabled", "enabled", null),
                new BehaviorDelta("ScanDuration", "increase", null,
                    "Reachability analysis adds processing time"),
                new BehaviorDelta("OutputDetail", "basic", "enhanced",
                    "Reachability data added to findings")
            ]);

        // Act
        var result = await TestConfigBehavioralDeltaAsync(
            baselineConfig,
            changedConfig,
            getBehavior: async config => await CaptureReachabilityBehaviorAsync(config),
            computeDelta: ComputeBehaviorSnapshotDelta,
            expectedDelta: expectedDelta);

        // Assert
        result.IsSuccess.Should().BeTrue(
            because: "enabling reachability should produce expected behavioral delta");
    }

    /// <summary>
    /// Verifies that changing SBOM format only affects output.
    /// </summary>
    [Fact]
    public async Task ChangingSbomFormat_OnlyAffectsOutput()
    {
        // Arrange
        var baselineConfig = new ScannerTestConfig { SbomFormat = "spdx-3.0" };
        var changedConfig = new ScannerTestConfig { SbomFormat = "cyclonedx-1.7" };

        // Act
        var result = await TestConfigIsolationAsync(
            baselineConfig,
            changedConfig,
            changedSetting: "SbomFormat",
            unrelatedBehaviors:
            [
                async config => await GetScanningBehaviorAsync(config),
                async config => await GetVulnMatchingBehaviorAsync(config),
                async config => await GetReachabilityBehaviorAsync(config)
            ]);

        // Assert
        result.IsSuccess.Should().BeTrue(
            because: "SBOM format should only affect output serialization");
    }

    /// <summary>
    /// Verifies that changing concurrency produces expected delta.
    /// </summary>
    [Fact]
    public async Task ChangingConcurrency_ProducesExpectedDelta()
    {
        // Arrange
        var baselineConfig = new ScannerTestConfig { MaxConcurrentAnalyzers = 2 };
        var changedConfig = new ScannerTestConfig { MaxConcurrentAnalyzers = 8 };

        var expectedDelta = new ConfigDelta(
            ChangedBehaviors: ["ParallelismLevel", "ResourceUsage"],
            BehaviorDeltas:
            [
                new BehaviorDelta("ParallelismLevel", "2", "8", null),
                new BehaviorDelta("ResourceUsage", "increase", null,
                    "More concurrent analyzers use more resources")
            ]);

        // Act
        var result = await TestConfigBehavioralDeltaAsync(
            baselineConfig,
            changedConfig,
            getBehavior: async config => await CaptureConcurrencyBehaviorAsync(config),
            computeDelta: ComputeBehaviorSnapshotDelta,
            expectedDelta: expectedDelta);

        // Assert
        result.IsSuccess.Should().BeTrue();
    }

    /// <summary>
    /// Verifies that changing vulnerability threshold only affects filtering.
    /// </summary>
    [Fact]
    public async Task ChangingVulnThreshold_OnlyAffectsFiltering()
    {
        // Arrange
        var baselineConfig = new ScannerTestConfig { MinimumSeverity = "medium" };
        var changedConfig = new ScannerTestConfig { MinimumSeverity = "critical" };

        // Act
        var result = await TestConfigIsolationAsync(
            baselineConfig,
            changedConfig,
            changedSetting: "MinimumSeverity",
            unrelatedBehaviors:
            [
                async config => await GetScanningBehaviorAsync(config),
                async config => await GetSbomBehaviorAsync(config)
            ]);

        // Assert
        result.IsSuccess.Should().BeTrue(
            because: "severity threshold should only affect output filtering");
    }

    // Helper methods

    private static Task<object> GetReachabilityBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { Enabled = config.EnableReachabilityAnalysis });
    }

    private static Task<object> GetConcurrencyBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { MaxAnalyzers = config.MaxConcurrentAnalyzers });
    }

    private static Task<object> GetOutputFormatBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { Format = config.SbomFormat });
    }

    private static Task<object> GetScanningBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { Depth = config.MaxScanDepth });
    }

    private static Task<object> GetVulnMatchingBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { MatchingMode = "standard" });
    }

    private static Task<object> GetSbomBehaviorAsync(ScannerTestConfig config)
    {
        return Task.FromResult<object>(new { Format = config.SbomFormat });
    }

    private static Task<BehaviorSnapshot> CaptureReachabilityBehaviorAsync(ScannerTestConfig config)
    {
        var snapshot = new BehaviorSnapshot(
            ConfigurationId: $"reachability-{config.EnableReachabilityAnalysis}",
            Behaviors:
            [
                new CapturedBehavior("ReachabilityMode",
                    config.EnableReachabilityAnalysis ? "enabled" : "disabled", DateTimeOffset.UtcNow),
                new CapturedBehavior("ScanDuration",
                    config.EnableReachabilityAnalysis ? "increase" : "standard", DateTimeOffset.UtcNow),
                new CapturedBehavior("OutputDetail",
                    config.EnableReachabilityAnalysis ? "enhanced" : "basic", DateTimeOffset.UtcNow)
            ],
            CapturedAt: DateTimeOffset.UtcNow);

        return Task.FromResult(snapshot);
    }

    private static Task<BehaviorSnapshot> CaptureConcurrencyBehaviorAsync(ScannerTestConfig config)
    {
        var snapshot = new BehaviorSnapshot(
            ConfigurationId: $"concurrency-{config.MaxConcurrentAnalyzers}",
            Behaviors:
            [
                new CapturedBehavior("ParallelismLevel", config.MaxConcurrentAnalyzers.ToString(), DateTimeOffset.UtcNow),
                new CapturedBehavior("ResourceUsage",
                    config.MaxConcurrentAnalyzers > 4 ? "increase" : "standard", DateTimeOffset.UtcNow)
            ],
            CapturedAt: DateTimeOffset.UtcNow);

        return Task.FromResult(snapshot);
    }
}

/// <summary>
/// Test configuration for Scanner module.
/// </summary>
public sealed record ScannerTestConfig
{
    public int MaxScanDepth { get; init; } = 10;
    public bool EnableReachabilityAnalysis { get; init; } = true;
    public int MaxConcurrentAnalyzers { get; init; } = 4;
    public string SbomFormat { get; init; } = "spdx-3.0";
    public string MinimumSeverity { get; init; } = "medium";
    public bool IncludeDevDependencies { get; init; } = false;
}