using System;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection;
using Svrnty.CQRS.Configuration;

namespace Svrnty.CQRS.Grpc;

/// <summary>
/// Extension methods for CqrsBuilder to add gRPC support
/// </summary>
public static class CqrsBuilderExtensions
{
    /// <summary>
    /// Adds gRPC support to the CQRS pipeline
    /// </summary>
    /// <param name="builder">The CQRS builder</param>
    /// <param name="configure">Optional configuration for gRPC endpoints</param>
    /// <returns>The CQRS builder for method chaining</returns>
    public static CqrsBuilder AddGrpc(this CqrsBuilder builder, Action<GrpcCqrsOptions>? configure = null)
    {
        var options = new GrpcCqrsOptions();
        configure?.Invoke(options);
        builder.Configuration.SetConfiguration(options);

        // Try to find and call the generated AddGrpcFromConfiguration method for service registration
        var addGrpcMethod = FindExtensionMethod("AddGrpcFromConfiguration", typeof(IServiceCollection));
        if (addGrpcMethod != null)
        {
            addGrpcMethod.Invoke(null, new object[] { builder.Services });
        }
        else
        {
            Console.WriteLine("Warning: AddGrpcFromConfiguration not found. gRPC services were not registered.");
            Console.WriteLine("Make sure your project has source generators enabled and references Svrnty.CQRS.Grpc.Generators.");
            DiagnoseGeneratedCode();
        }

        // Register mapping callback for automatic endpoint mapping
        builder.Configuration.AddMappingCallback(app =>
        {
            // Find the generated MapGrpcFromConfiguration method
            var mapGrpcMethod = FindExtensionMethod("MapGrpcFromConfiguration", typeof(Microsoft.AspNetCore.Routing.IEndpointRouteBuilder));
            if (mapGrpcMethod != null)
            {
                mapGrpcMethod.Invoke(null, new object[] { app });
            }
        });

        return builder;
    }

    private static void DiagnoseGeneratedCode()
    {
        var entryAsm = Assembly.GetEntryAssembly();
        if (entryAsm == null)
        {
            Console.WriteLine("Diagnostic: Entry assembly is null");
            return;
        }

        Console.WriteLine($"Diagnostic: Entry assembly = {entryAsm.GetName().Name}");

        try
        {
            var allTypes = entryAsm.GetTypes();
            Console.WriteLine($"Diagnostic: Total types in entry assembly = {allTypes.Length}");

            var grpcTypes = allTypes
                .Where(t => t.FullName?.Contains("Grpc") == true)
                .ToList();

            if (grpcTypes.Any())
            {
                Console.WriteLine("Diagnostic: Found Grpc-related types:");
                foreach (var t in grpcTypes)
                {
                    Console.WriteLine($"  - {t.FullName} (IsClass={t.IsClass}, IsSealed={t.IsSealed}, IsPublic={t.IsPublic})");

                    // Check for our target method
                    var method = t.GetMethod("AddGrpcFromConfiguration", BindingFlags.Static | BindingFlags.Public);
                    if (method != null)
                        Console.WriteLine($"    -> HAS AddGrpcFromConfiguration method!");
                }
            }
            else
            {
                Console.WriteLine("Diagnostic: No Grpc-related types found. Source generator did NOT run.");
            }
        }
        catch (ReflectionTypeLoadException ex)
        {
            Console.WriteLine($"Diagnostic: ReflectionTypeLoadException - {ex.Message}");
            foreach (var le in ex.LoaderExceptions)
            {
                if (le != null)
                    Console.WriteLine($"  LoaderException: {le.Message}");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Diagnostic: Exception - {ex.GetType().Name}: {ex.Message}");
        }
    }

    private static MethodInfo? FindExtensionMethod(string methodName, Type parameterType)
    {
        // Search through all loaded assemblies for the extension method
        foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
        {
            try
            {
                var types = assembly.GetTypes()
                    .Where(t => t.IsClass && t.IsSealed && !t.IsGenericType && t.IsPublic);

                foreach (var type in types)
                {
                    var method = type.GetMethod(methodName,
                        BindingFlags.Static | BindingFlags.Public,
                        null,
                        new[] { parameterType },
                        null);

                    if (method != null)
                        return method;
                }
            }
            catch
            {
                // Skip assemblies that can't be inspected
            }
        }

        return null;
    }
}