using Bootstrap.DataAccess.Helper;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.IO;
using System.Linq;

namespace Microsoft.AspNetCore.Builder
{
 /// <summary>
 /// 自动生成数据库扩展操作类
 /// </summary>
 public static class AutoGenerateDatabaseExtensions
 {
 private static bool _init;
 private static object _locker = new object();
 private const string SqlFolderKey = "SqlFolder";
 /// <summary>
 /// 自动生成数据库中间件
 /// </summary>
 /// <param name="app"></param>
 public static IApplicationBuilder UseAutoGenerateDatabase(this IApplicationBuilder app)
 {
 app.Use(async (context, next) =>
 {
 if (!_init)
 {
 // 优化性能
 var config = context.RequestServices.GetRequiredService<IConfiguration>();
 var autoGenerate = config.GetValue("AutoGenerateDatabase", false);
 if (!autoGenerate) _init = true;
 if (autoGenerate)
 {
 // 阻止所有线程继续往下运行,等待数据库检查
 lock (_locker)
 {
 if (!_init)
 {
 // 数据检查
 var dbSection = config.GetSection("DB").GetChildren().FirstOrDefault(c => c.GetValue("Enabled", false));
 if (dbSection != null)
 {
 var folder = dbSection.GetValue(SqlFolderKey, "").ReplaceOSPlatformPath();
 if (!string.IsNullOrEmpty(folder))
 {
 // 判断文件夹是否存在
 var env = context.RequestServices.GetRequiredService<IWebHostEnvironment>();
 var fullFolder = Path.Combine(env.ContentRootPath, folder);
 if (Directory.Exists(fullFolder))
 {
 try
 {
 AutoDbHelper.EnsureCreated(fullFolder);
 }
 catch { }
 }
 }
 }
 }
 _init = true;
 }
 }
 }
 await next();
 });
 return app;
 }
 }
}