// Copyright (c) 2025-2026 GeWuYou
// SPDX-License-Identifier: Apache-2.0

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using GFramework.Core.Abstractions.Logging;
using GFramework.Core.Ioc;
using GFramework.Cqrs.Abstractions.Cqrs;
using GFramework.Cqrs.Internal;
using MediatR;
using Microsoft.Extensions.DependencyInjection;
using LegacyICqrsRuntime = GFramework.Core.Abstractions.Cqrs.ICqrsRuntime;

namespace GFramework.Cqrs.Benchmarks.Messaging;

/// <summary>
///     为 benchmark 场景构建最小且可重复的 GFramework / MediatR 对照宿主。
/// </summary>
/// <remarks>
///     基准工程里的对照目标是“相同消息合同下的调度差异”，而不是程序集扫描量或容器生命周期差异。
///     因此这里统一封装两类宿主的最小注册形状，确保：
///     1. GFramework 容器在首次发送前已经冻结，可真实解析按类型注册的 handler；
///     2. MediatR 只扫描当前 benchmark 明确拥有的 handler / behavior 类型，避免整个程序集的额外注册污染结果。
/// </remarks>
internal static class BenchmarkHostFactory
{
    /// <summary>
    ///     创建一个已经冻结的 GFramework benchmark 容器。
    /// </summary>
    /// <param name="configure">向容器写入 benchmark 所需 handler / pipeline 的注册动作。</param>
    /// <returns>已冻结、可立即用于 runtime 分发的容器。</returns>
    internal static MicrosoftDiContainer CreateFrozenGFrameworkContainer(Action<MicrosoftDiContainer> configure)
    {
        ArgumentNullException.ThrowIfNull(configure);

        var container = new MicrosoftDiContainer();
        RegisterCqrsInfrastructure(container);
        configure(container);
        container.Freeze();
        return container;
    }

    /// <summary>
    ///     为 benchmark 宿主补齐默认 CQRS runtime seam，确保它既能手工注册 handler，也能走真实的程序集注册入口。
    /// </summary>
    /// <param name="container">当前 benchmark 拥有的 GFramework 容器。</param>
    /// <remarks>
    ///     `RegisterCqrsHandlersFromAssembly(...)` 依赖预先可见的 runtime / registrar / registration service 实例绑定。
    ///     benchmark 宿主直接使用裸 <see cref="MicrosoftDiContainer" />，因此需要在配置阶段先补齐这组基础设施，
    ///     避免各个 benchmark 用例各自复制同一段前置接线逻辑。
    /// </remarks>
    private static void RegisterCqrsInfrastructure(MicrosoftDiContainer container)
    {
        ArgumentNullException.ThrowIfNull(container);

        if (container.Get<ICqrsRuntime>() is null)
        {
            var runtimeLogger = LoggerFactoryResolver.Provider.CreateLogger("CqrsDispatcher");
            var notificationPublisher = container.Get<GFramework.Cqrs.Notification.INotificationPublisher>();
            var runtime = GFramework.Cqrs.CqrsRuntimeFactory.CreateRuntime(container, runtimeLogger, notificationPublisher);
            container.Register(runtime);
            RegisterLegacyRuntimeAlias(container, runtime);
        }
        else if (container.Get<LegacyICqrsRuntime>() is null)
        {
            RegisterLegacyRuntimeAlias(container, container.GetRequired<ICqrsRuntime>());
        }

        if (container.Get<ICqrsHandlerRegistrar>() is null)
        {
            var registrarLogger = LoggerFactoryResolver.Provider.CreateLogger("DefaultCqrsHandlerRegistrar");
            var registrar = GFramework.Cqrs.CqrsRuntimeFactory.CreateHandlerRegistrar(container, registrarLogger);
            container.Register<ICqrsHandlerRegistrar>(registrar);
        }

        if (container.Get<ICqrsRegistrationService>() is null)
        {
            var registrationLogger = LoggerFactoryResolver.Provider.CreateLogger("DefaultCqrsRegistrationService");
            var registrar = container.GetRequired<ICqrsHandlerRegistrar>();
            var registrationService = GFramework.Cqrs.CqrsRuntimeFactory.CreateRegistrationService(registrar, registrationLogger);
            container.Register<ICqrsRegistrationService>(registrationService);
        }
    }

    /// <summary>
    ///     只激活当前 benchmark 场景明确拥有的 generated registry，避免同一程序集里的其他 benchmark registry
    ///     扩大冻结后服务索引与 dispatcher descriptor 基线。
    /// </summary>
    /// <typeparam name="TRegistry">当前 benchmark 需要接入的 generated registry 类型。</typeparam>
    /// <param name="container">承载 generated registry 注册结果的 GFramework benchmark 容器。</param>
    internal static void RegisterGeneratedBenchmarkRegistry<TRegistry>(MicrosoftDiContainer container)
        where TRegistry : class, GFramework.Cqrs.ICqrsHandlerRegistry
    {
        ArgumentNullException.ThrowIfNull(container);

        var registrarLogger = LoggerFactoryResolver.Provider.CreateLogger("DefaultCqrsHandlerRegistrar");
        CqrsHandlerRegistrar.RegisterGeneratedRegistry(container, typeof(TRegistry), registrarLogger);
    }

    /// <summary>
    ///     为旧命名空间下的 CQRS runtime 契约注册兼容别名。
    /// </summary>
    /// <param name="container">承载 runtime 别名的 benchmark 容器。</param>
    /// <param name="runtime">当前正式 CQRS runtime 实例。</param>
    /// <exception cref="InvalidOperationException">
    ///     <paramref name="runtime" /> 未同时实现 legacy CQRS runtime 契约。
    /// </exception>
    private static void RegisterLegacyRuntimeAlias(MicrosoftDiContainer container, ICqrsRuntime runtime)
    {
        ArgumentNullException.ThrowIfNull(container);
        ArgumentNullException.ThrowIfNull(runtime);

        if (runtime is not LegacyICqrsRuntime legacyRuntime)
        {
            throw new InvalidOperationException(
                $"The registered {typeof(ICqrsRuntime).FullName} must also implement {typeof(LegacyICqrsRuntime).FullName}. Actual runtime type: {runtime.GetType().FullName}.");
        }

        container.Register<LegacyICqrsRuntime>(legacyRuntime);
    }

    /// <summary>
    ///     创建只承载当前 benchmark handler 集合的最小 MediatR 宿主。
    /// </summary>
    /// <param name="configure">补充当前场景的显式服务注册，例如手工单例 handler 或 pipeline 行为。</param>
    /// <param name="handlerAssemblyMarkerType">用于限定扫描程序集的标记类型。</param>
    /// <param name="handlerTypeFilter">
    ///     仅允许当前 benchmark 场景需要的 handler / behavior 类型通过扫描；
    ///     这样可保留 `AddMediatR` 的正常装配路径，同时避免整个基准程序集里的其他 handler 被一并注册。
    /// </param>
    /// <param name="lifetime">当前 benchmark 希望 MediatR 使用的默认注册生命周期。</param>
    /// <returns>只承载当前 benchmark 场景所需服务的 DI 宿主。</returns>
    internal static ServiceProvider CreateMediatRServiceProvider(
        Action<IServiceCollection>? configure,
        Type handlerAssemblyMarkerType,
        Func<Type, bool> handlerTypeFilter,
        ServiceLifetime lifetime = ServiceLifetime.Transient)
    {
        ArgumentNullException.ThrowIfNull(handlerAssemblyMarkerType);
        ArgumentNullException.ThrowIfNull(handlerTypeFilter);

        var services = new ServiceCollection();
        services.AddLogging(static builder =>
            Microsoft.Extensions.Logging.FilterLoggingBuilderExtensions.AddFilter(
                builder,
                "LuckyPennySoftware.MediatR.License",
                Microsoft.Extensions.Logging.LogLevel.None));

        configure?.Invoke(services);

        services.AddMediatR(options =>
        {
            options.Lifetime = lifetime;
            options.TypeEvaluator = handlerTypeFilter;
            options.RegisterServicesFromAssembly(handlerAssemblyMarkerType.Assembly);
        });

        return services.BuildServiceProvider();
    }

    /// <summary>
    ///     在真实的 request 级作用域内执行一次 GFramework.CQRS request 分发。
    /// </summary>
    /// <typeparam name="TResponse">请求响应类型。</typeparam>
    /// <param name="runtime">复用的 scoped benchmark runtime。</param>
    /// <param name="scopedContainer">负责为每次 request 激活独立作用域的只读容器适配层。</param>
    /// <param name="context">当前 CQRS 分发上下文。</param>
    /// <param name="request">要发送的 request。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>当前 request 的响应结果。</returns>
    /// <remarks>
    ///     该入口只服务 request lifetime benchmark：它会复用同一个 dispatcher/runtime 实例，
    ///     但在每次调用前后显式创建并释放新的 DI 作用域，
    ///     让 `Scoped` handler 在真实 request 边界内解析，而不是退化为根容器解析或额外计入 runtime 构造成本。
    /// </remarks>
    internal static async ValueTask<TResponse> SendScopedGFrameworkRequestAsync<TResponse>(
        ICqrsRuntime runtime,
        ScopedBenchmarkContainer scopedContainer,
        ICqrsContext context,
        GFramework.Cqrs.Abstractions.Cqrs.IRequest<TResponse> request,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(runtime);
        ArgumentNullException.ThrowIfNull(scopedContainer);
        ArgumentNullException.ThrowIfNull(context);
        ArgumentNullException.ThrowIfNull(request);

        using var scopeLease = scopedContainer.EnterScope();
        return await runtime.SendAsync(context, request, cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    ///     在真实的 request 级作用域内执行一次 MediatR request 分发。
    /// </summary>
    /// <typeparam name="TResponse">请求响应类型。</typeparam>
    /// <param name="rootServiceProvider">当前 benchmark 的根 <see cref="ServiceProvider" />。</param>
    /// <param name="request">要发送的 request。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>当前 request 的响应结果。</returns>
    /// <remarks>
    ///     这里显式从新的 scope 解析 <see cref="IMediator" />，确保 `Scoped` handler 与其依赖绑定到 request 边界。
    /// </remarks>
    internal static async Task<TResponse> SendScopedMediatRRequestAsync<TResponse>(
        ServiceProvider rootServiceProvider,
        MediatR.IRequest<TResponse> request,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(rootServiceProvider);
        ArgumentNullException.ThrowIfNull(request);

        using var scope = rootServiceProvider.CreateScope();
        var mediator = scope.ServiceProvider.GetRequiredService<IMediator>();
        return await mediator.Send(request, cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    ///     在真实的 request 级作用域内创建一次 GFramework.CQRS stream，并让该作用域覆盖整个异步枚举周期。
    /// </summary>
    /// <typeparam name="TResponse">stream 响应元素类型。</typeparam>
    /// <param name="runtime">复用的 scoped benchmark runtime。</param>
    /// <param name="scopedContainer">负责为每次 stream 激活独立作用域的只读容器适配层。</param>
    /// <param name="context">当前 CQRS 分发上下文。</param>
    /// <param name="request">要创建 stream 的 request。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>绑定到单次显式作用域的异步响应序列。</returns>
    /// <remarks>
    ///     stream 与 request 的区别在于：handler 解析发生在建流时，但 scoped 依赖必须一直存活到枚举完成。
    ///     因此这里返回一个包装后的 async iterator，把 scope 的释放时机推迟到调用方结束枚举之后，
    ///     避免 `Scoped` handler 退化成“建流后立刻释放 scope，再在根容器语义下继续枚举”的错误模型。
    /// </remarks>
    internal static IAsyncEnumerable<TResponse> CreateScopedGFrameworkStream<TResponse>(
        ICqrsRuntime runtime,
        ScopedBenchmarkContainer scopedContainer,
        ICqrsContext context,
        GFramework.Cqrs.Abstractions.Cqrs.IStreamRequest<TResponse> request,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(runtime);
        ArgumentNullException.ThrowIfNull(scopedContainer);
        ArgumentNullException.ThrowIfNull(context);
        ArgumentNullException.ThrowIfNull(request);

        return EnumerateScopedGFrameworkStreamAsync(runtime, scopedContainer, context, request, cancellationToken);
    }

    /// <summary>
    ///     在真实的 request 级作用域内创建一次 MediatR stream，并让该作用域覆盖整个异步枚举周期。
    /// </summary>
    /// <typeparam name="TResponse">stream 响应元素类型。</typeparam>
    /// <param name="rootServiceProvider">当前 benchmark 的根 <see cref="ServiceProvider" />。</param>
    /// <param name="request">要创建 stream 的 request。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>绑定到单次显式作用域的异步响应序列。</returns>
    /// <remarks>
    ///     这里与 scoped request helper 保持同一组边界约束，但把 scope 生命周期延长到 stream 完整枚举结束，
    ///     确保 `Scoped` handler 与依赖不会在首个元素产出前后被提前释放。
    /// </remarks>
    internal static IAsyncEnumerable<TResponse> CreateScopedMediatRStream<TResponse>(
        ServiceProvider rootServiceProvider,
        MediatR.IStreamRequest<TResponse> request,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(rootServiceProvider);
        ArgumentNullException.ThrowIfNull(request);

        return EnumerateScopedMediatRStreamAsync(rootServiceProvider, request, cancellationToken);
    }

    /// <summary>
    ///     创建承载 NuGet `Mediator` source-generated concrete mediator 的最小对照宿主。
    /// </summary>
    /// <param name="configure">补充当前场景的显式服务注册。</param>
    /// <returns>可直接解析 generated `Mediator.Mediator` 的 DI 宿主。</returns>
    /// <remarks>
    ///     当前 benchmark 只把 `Mediator` 作为单例 steady-state 对照组接入，
    ///     因为它的 lifetime 由 source generator 在编译期塑形；若后续需要 `Transient` / `Scoped` 矩阵，
    ///     应按 `Mediator` 官方 benchmark 的做法拆成独立 build config，而不是在同一编译产物里混用多个 lifetime。
    /// </remarks>
    internal static ServiceProvider CreateMediatorServiceProvider(Action<IServiceCollection>? configure)
    {
        var services = new ServiceCollection();
        configure?.Invoke(services);
        services.AddMediator();
        return services.BuildServiceProvider();
    }

    /// <summary>
    ///     判断某个类型是否正好实现了指定的闭合或开放 MediatR 合同。
    /// </summary>
    /// <param name="candidateType">待判断类型。</param>
    /// <param name="openGenericContract">目标开放泛型合同，例如 <see cref="MediatR.IRequestHandler{TRequest,TResponse}" />。</param>
    /// <returns>命中任一实现接口时返回 <see langword="true" />；否则返回 <see langword="false" />。</returns>
    internal static bool ImplementsOpenGenericContract(Type candidateType, Type openGenericContract)
    {
        ArgumentNullException.ThrowIfNull(candidateType);
        ArgumentNullException.ThrowIfNull(openGenericContract);

        return candidateType.GetInterfaces().Any(interfaceType =>
            interfaceType.IsGenericType &&
            interfaceType.GetGenericTypeDefinition() == openGenericContract);
    }

    /// <summary>
    ///     在单个显式作用域内创建并枚举 GFramework.CQRS stream。
    /// </summary>
    private static async IAsyncEnumerable<TResponse> EnumerateScopedGFrameworkStreamAsync<TResponse>(
        ICqrsRuntime runtime,
        ScopedBenchmarkContainer scopedContainer,
        ICqrsContext context,
        GFramework.Cqrs.Abstractions.Cqrs.IStreamRequest<TResponse> request,
        [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
    {
        using var scopeLease = scopedContainer.EnterScope();
        var stream = runtime.CreateStream(context, request, cancellationToken);

        await foreach (var response in stream.ConfigureAwait(false))
        {
            cancellationToken.ThrowIfCancellationRequested();
            yield return response;
        }
    }

    /// <summary>
    ///     在单个显式作用域内创建并枚举 MediatR stream。
    /// </summary>
    private static async IAsyncEnumerable<TResponse> EnumerateScopedMediatRStreamAsync<TResponse>(
        ServiceProvider rootServiceProvider,
        MediatR.IStreamRequest<TResponse> request,
        [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
    {
        using var scope = rootServiceProvider.CreateScope();
        var mediator = scope.ServiceProvider.GetRequiredService<IMediator>();
        var stream = mediator.CreateStream(request, cancellationToken);

        await foreach (var response in stream.ConfigureAwait(false))
        {
            cancellationToken.ThrowIfCancellationRequested();
            yield return response;
        }
    }
}