using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Hosting;

namespace ETFileServer
{
    public class Startup
    {
        private IConfiguration Configuration { get; }

        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            // 1. 从配置中获取文件根目录路径
            string fileRootPath = Configuration["DirectoryPath"];
            if (string.IsNullOrEmpty(fileRootPath))
            {
                throw new InvalidOperationException("DirectoryPath is not configured in appsettings.json.");
            }
            
            // 2. 解析为绝对路径
            string fullPath = Path.GetFullPath(fileRootPath);
            if (!Directory.Exists(fullPath))
            {
                // 在启动时检查目录是否存在，如果不存在则创建
                Directory.CreateDirectory(fullPath);
                Console.WriteLine($"Warning: Root directory not found. Created directory at: {fullPath}");
            }

            // 3. 创建并注册一个 PhysicalFileProvider 作为单例服务
            // 这样整个应用都可以安全地使用它来访问文件
            var provider = new PhysicalFileProvider(fullPath);
            services.AddSingleton<IFileProvider>(provider);
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });

            // 对于任何未匹配到Controller的请求，直接返回404 Not Found
            app.Run(context =>
            {
                context.Response.StatusCode = 404;
                return Task.CompletedTask;
            });
        }
    }
}