#if WINDOWS
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Hosting;
using System.Text.Json;
using Hua.Todo.Application;
using Hua.Todo.Application.DynamicApi;
using Hua.Todo.Maui.Models;
using AppSettings = Hua.Todo.Maui.Models.AppSettings;

namespace Hua.Todo.Maui.Services;

/// <summary>
/// Windows 平台嵌入式 Web 服务器实现
/// 使用 ASP.NET Core 运行
/// </summary>
public class EmbeddedWebServerService : IEmbeddedWebServerService
{
    private WebApplication? _webApp;
    private readonly AppSettings _appSettings;

    /// <summary>
    /// 服务器是否正在运行
    /// </summary>
    public bool IsRunning => _webApp != null;

    /// <summary>
    /// 服务器基础 URL
    /// </summary>
    public string BaseUrl => _appSettings.WebServer.HostUrl;

    /// <summary>
    /// 初始化嵌入式 Web 服务器服务
    /// </summary>
    /// <param name="appSettings">应用程序配置</param>
    public EmbeddedWebServerService(AppSettings appSettings)
    {
        _appSettings = appSettings;
    }

    /// <summary>
    /// 异步启动服务器。
    /// 启动时机：通常在应用启动或用户手动开启服务时调用。
    /// 错误处理：启动失败会抛出 ASP.NET Core 相关异常，建议在调用方进行 catch 处理。
    /// 线程安全：非 UI 线程相关，可在后台线程调用；方法内部已处理重入（若已运行则直接返回）。
    /// </summary>
    /// <returns>表示启动操作的任务</returns>
    public async Task StartAsync()
    {
        if (_webApp != null) return;

        var builder = WebApplication.CreateBuilder();

        builder.WebHost.UseUrls(_appSettings.WebServer.HostUrl);

        // 配置控制器和 JSON 选项
        builder.Services.AddControllers()
            .AddApplicationPart(typeof(Hua.Todo.Application.ServiceCollectionExtensions).Assembly)
            .AddJsonOptions(options =>
            {
                options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
            });

        builder.Services.AddEndpointsApiExplorer();

        // 注册应用逻辑服务
        builder.Services.AddApplicationServices(_appSettings.WebServer.ConnectionString);

        // 配置跨域策略
        builder.Services.AddCors(options =>
        {
            options.AddPolicy("AllowAll", policy =>
            {
                policy.AllowAnyOrigin()
                      .AllowAnyMethod()
                      .AllowAnyHeader();
            });
        });

        var app = builder.Build();

        // 如果配置为使用静态文件（前端托管），则配置静态文件服务
        if (_appSettings.WebServer.IsUsingStatic)
        {
            ServeStaticFiles(app);
        }

        app.UseCors("AllowAll");
        app.UseAuthorization();
        app.UseDynamicApi();
        app.MapControllers();

        _webApp = app;

        await _webApp.StartAsync();
    }

    /// <summary>
    /// 配置静态文件服务（用于托管 Vue 前端）
    /// </summary>
    /// <param name="app">Web 应用程序实例</param>
    private void ServeStaticFiles(WebApplication app)
    {
        try
        {
            var wwwrootPath = Path.Combine(AppContext.BaseDirectory, "wwwroot");
            if (!Directory.Exists(wwwrootPath))
            {
                Console.WriteLine("[EmbeddedWebServer] wwwroot directory not found. Static file serving disabled.");
                return;
            }
            var fileProvider = new PhysicalFileProvider(wwwrootPath);
            var defaultFilesOptions = new DefaultFilesOptions { FileProvider = fileProvider, RequestPath = "" };
            app.UseDefaultFiles(defaultFilesOptions);

            var staticFileOptions = new StaticFileOptions
            {
                FileProvider = fileProvider,
                RequestPath = "",
                OnPrepareResponse = ctx =>
                {
                    ctx.Context.Response.Headers["Cache-Control"] = "no-cache, no-store, must-revalidate";
                    ctx.Context.Response.Headers["Pragma"] = "no-cache";
                    ctx.Context.Response.Headers["Expires"] = "0";
                }
            };
            app.UseStaticFiles(staticFileOptions);

            // 处理 SPA 路由
            app.Use(async (context, next) =>
            {
                if (context.Request.Path.HasValue)
                {
                    var path = context.Request.Path.Value;
                    if (path != "/" && !path.StartsWith("/assets", StringComparison.OrdinalIgnoreCase) && !path.StartsWith("/api", StringComparison.OrdinalIgnoreCase))
                    {
                        var ext = Path.GetExtension(path);
                        if (string.IsNullOrEmpty(ext))
                        {
                            context.Request.Path = "/index.html";
                        }
                    }
                }
                await next();
            });

            Console.WriteLine($"[EmbeddedWebServer] Serving static files from: {wwwrootPath}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[EmbeddedWebServer] Failed to serve static files: {ex.Message}");
        }
    }

    /// <summary>
    /// 异步停止服务器。
    /// 释放服务器资源并停止监听。
    /// </summary>
    /// <returns>表示停止操作的任务</returns>
    public async Task StopAsync()
    {
        if (_webApp == null) return;

        await _webApp.StopAsync();
        await _webApp.DisposeAsync();
        _webApp = null;
    }
}
#endif