using System.Reflection;
using NetArchTest.Rules;
using Xunit;
using FluentAssertions;

namespace StellaOps.Architecture.Tests;

/// <summary>
/// Architecture tests for lattice engine placement rules.
/// Ensures lattice algorithms are only in Scanner.WebService, not in Concelier or Excititor.
/// </summary>
[Trait("Category", "Architecture")]
public sealed class LatticeEngineRulesTests
{
    private const string ScannerLatticeNamespace = "StellaOps.Scanner.Lattice";

    /// <summary>
    /// Concelier modules must not reference Scanner lattice engine.
    /// Lattice decisions are made in Scanner, not in Concelier.
    /// </summary>
    [Fact]
    public void Concelier_MustNot_Reference_ScannerLattice()
    {
        var concelierAssemblies = GetAssembliesByPattern("StellaOps.Concelier");
        
        if (!concelierAssemblies.Any())
        {
            // Skip if assemblies not loaded (test discovery phase)
            return;
        }

        var result = Types.InAssemblies(concelierAssemblies)
            .ShouldNot()
            .HaveDependencyOn(ScannerLatticeNamespace)
            .GetResult();

        result.IsSuccessful.Should().BeTrue(
            $"Concelier assemblies must not reference Scanner lattice. " +
            $"Violations: {string.Join(", ", result.FailingTypeNames ?? Enumerable.Empty<string>())}");
    }

    /// <summary>
    /// Excititor modules must not reference Scanner lattice engine.
    /// Excititor preserves prune source - does not evaluate lattice decisions.
    /// </summary>
    [Fact]
    public void Excititor_MustNot_Reference_ScannerLattice()
    {
        var excititorAssemblies = GetAssembliesByPattern("StellaOps.Excititor");
        
        if (!excititorAssemblies.Any())
        {
            return;
        }

        var result = Types.InAssemblies(excititorAssemblies)
            .ShouldNot()
            .HaveDependencyOn(ScannerLatticeNamespace)
            .GetResult();

        result.IsSuccessful.Should().BeTrue(
            $"Excititor assemblies must not reference Scanner lattice. " +
            $"Violations: {string.Join(", ", result.FailingTypeNames ?? Enumerable.Empty<string>())}");
    }

    /// <summary>
    /// Scanner.WebService MAY reference Scanner lattice engine (it's the authorized host).
    /// This test documents the allowed dependency.
    /// </summary>
    [Fact]
    public void ScannerWebService_May_Reference_ScannerLattice()
    {
        // This is a documentation test - Scanner.WebService is allowed to use lattice
        // The test validates that the architectural rule is correctly documented
        var allowedAssemblies = new[] { "StellaOps.Scanner.WebService" };
        
        // Positive assertion: these assemblies ARE allowed to reference lattice
        allowedAssemblies.Should().Contain("StellaOps.Scanner.WebService",
            "Scanner.WebService is the authorized host for lattice algorithms");
    }

    private static IEnumerable<Assembly> GetAssembliesByPattern(string pattern)
    {
        return AppDomain.CurrentDomain.GetAssemblies()
            .Where(a => a.GetName().Name?.StartsWith(pattern) == true);
    }
}