using Microsoft.AspNetCore.Http;
using System.IO;
using System.Threading.Tasks;
using System.Web;

namespace WMS.Util
{
	public static class FileDownloadExtensions
	{
		public static async Task DownloadAsync(this HttpContext context, string fileName, string filePath)
		{
			if (!File.Exists(filePath))
			{
				context.Response.StatusCode = StatusCodes.Status404NotFound;
				await context.Response.WriteAsync("File not found.");
				return;
			}

			var memory = new MemoryStream();
			using var stream = new FileStream(filePath, FileMode.Open);
			await stream.CopyToAsync(memory);
			memory.Position = 0;

			var contentType = GetContentType(filePath);
			context.Response.ContentType = contentType;
			context.Response.Headers.Add("Content-Disposition", $"attachment; filename={fileName}");
			context.Response.StatusCode = StatusCodes.Status200OK;
			await context.Response.Body.WriteAsync(memory.ToArray());
		}

		private static string GetContentType(string path)
		{
			var types = new Dictionary<string, string>
			{
				{".txt", "text/plain"},
				{".pdf", "application/pdf"},
                // add more file types
            };

			var ext = Path.GetExtension(path).ToLowerInvariant();
			return types.ContainsKey(ext) ? types[ext] : "application/octet-stream";
		}
	}
	/// <summary>
	/// 描 述：文件下载类
	/// </summary>
	public class FileDownUtil
	{

		public FileDownUtil()
		{ }
		//       /// <summary>
		//       /// 参数为虚拟路径
		//       /// </summary>
		//       public static string FileNameExtension(string FileName)
		//       {
		//           return Path.GetExtension(MapPathFile(FileName));
		//       }
		/// <summary>
		/// 获取物理地址
		/// </summary>
		public static string MapPathFile(string FileName)
		{
			return ConfigHelper.GetValue<string>("baseDir");
			//return Directory.GetCurrentDirectory();
		}
		//       /// <summary>
		//       /// 验证文件是否存在
		//       /// </summary>
		//       /// <param name="FileName"></param>
		//       /// <returns></returns>
		//       public static bool FileExists(string FileName)
		//       {
		//           string destFileName = FileName;
		//           if (File.Exists(destFileName))
		//           {
		//               return true;
		//           }
		//           else
		//           {
		//               return false;
		//           }
		//       }


		//	/// <summary>
		//	/// 普通下载
		//	/// </summary>
		//	/// <param name="FileName">文件虚拟路径</param>
		//	///  /// <param name="name">返回客户端名称</param>
		//	public static void DownLoadold(string FileName, string name)
		//       {
		//           string destFileName = FileName;
		//           if (File.Exists(destFileName))
		//           {
		//               FileInfo fi = new FileInfo(destFileName);
		//               HttpContext.Current.Response.Clear();
		//               HttpContext.Current.Response.ClearHeaders();
		//               HttpContext.Current.Response.Buffer = false;
		//               HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(name, System.Text.Encoding.UTF8));
		//               HttpContext.Current.Response.AppendHeader("Content-Length", fi.Length.ToString());
		//               HttpContext.Current.Response.ContentType = "application/octet-stream";
		//               HttpContext.Current.Response.WriteFile(destFileName);
		//               HttpContext.Current.Response.Flush();
		//               HttpContext.Current.Response.End();
		//           }
		//       }
		//       /// <summary>
		//       /// 分块下载
		//       /// </summary>
		//       /// <param name="FileName">文件虚拟路径</param>
		//       public static void DownLoad(string FileName)
		//       {
		//           string filePath = MapPathFile(FileName);
		//           long chunkSize = 204800;             //指定块大小 
		//           byte[] buffer = new byte[chunkSize]; //建立一个200K的缓冲区 
		//           long dataToRead = 0;                 //已读的字节数   
		//           FileStream stream = null;
		//           try
		//           {
		//               //打开文件   
		//               stream = new FileStream(FileName, FileMode.Open, FileAccess.Read, FileShare.Read);
		//               dataToRead = stream.Length;

		//               //添加Http头   
		//               HttpContext.Current.Response.ContentType = "application/octet-stream";
		//               HttpContext.Current.Response.AddHeader("Content-Disposition", "attachement;filename=" + HttpUtility.UrlEncode(Path.GetFileName(filePath)));
		//               HttpContext.Current.Response.AddHeader("Content-Length", dataToRead.ToString());

		//               while (dataToRead > 0)
		//               {
		//                   if (HttpContext.Current.Response.IsClientConnected)
		//                   {
		//                       int length = stream.Read(buffer, 0, Convert.ToInt32(chunkSize));
		//                       HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);
		//                       HttpContext.Current.Response.Flush();
		//                       HttpContext.Current.Response.Clear();
		//                       dataToRead -= length;
		//                   }
		//                   else
		//                   {
		//                       dataToRead = -1; //防止client失去连接 
		//                   }
		//               }
		//           }
		//           catch (Exception ex)
		//           {
		//               HttpContext.Current.Response.Write("Error:" + ex.Message);
		//           }
		//           finally
		//           {
		//               if (stream != null) stream.Close();
		//               HttpContext.Current.Response.Close();
		//           }
		//       }

		//       /// <summary>
		//       /// 分块下载
		//       /// </summary>
		//       /// <param name="stream">文件流</param>
		//       /// <param name="filename">文件名</param>
		//       public static void DownLoad(MemoryStream stream, string filename)
		//       {
		//           long chunkSize = 204800;             //指定块大小 
		//           byte[] buffer = new byte[chunkSize]; //建立一个200K的缓冲区 
		//           long dataToRead = 0;                 //已读的字节数   
		//           try
		//           {
		//               dataToRead = stream.Length;

		//               //添加Http头   
		//               HttpContext.Current.Response.ContentType = "application/octet-stream";
		//               HttpContext.Current.Response.AddHeader("Content-Disposition", "attachement;filename=" + filename);
		//               HttpContext.Current.Response.AddHeader("Content-Length", dataToRead.ToString());

		//               while (dataToRead > 0)
		//               {
		//                   if (HttpContext.Current.Response.IsClientConnected)
		//                   {
		//                       int length = stream.Read(buffer, 0, Convert.ToInt32(chunkSize));
		//                       HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);
		//                       HttpContext.Current.Response.Flush();
		//                       HttpContext.Current.Response.Clear();
		//                       dataToRead -= length;
		//                   }
		//                   else
		//                   {
		//                       dataToRead = -1; //防止client失去连接 
		//                   }
		//               }
		//           }
		//           catch (Exception ex)
		//           {
		//               HttpContext.Current.Response.Write("Error:" + ex.Message);
		//           }
		//           finally
		//           {
		//               if (stream != null) stream.Close();
		//               HttpContext.Current.Response.Close();
		//           }
		//       }

		/// <summary>
		/// 下载文件
		/// </summary>
		/// <param name="filePath">物理地址</param>
		public static void DownLoadnew(string filePath)
		{
			long chunkSize = 204800;             //指定块大小 
			byte[] buffer = new byte[chunkSize]; //建立一个200K的缓冲区 
			long dataToRead = 0;                 //已读的字节数   
			FileStream stream = null;
			try
			{
				//打开文件   
				stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
				dataToRead = stream.Length;

				//添加Http头   
				WebUtil.HttpContext.Response.ContentType = "application/octet-stream";
				WebUtil.HttpContext.Response.Headers.Add("Content-Disposition", "attachement;filename=" + HttpUtility.UrlEncode(Path.GetFileName(filePath)));
				WebUtil.HttpContext.Response.Headers.Add("Content-Length", dataToRead.ToString());

				while (dataToRead > 0)
				{
					if (WebUtil.HttpContext.Response.HasStarted)
					{
						int length = stream.Read(buffer, 0, Convert.ToInt32(chunkSize));
						WebUtil.HttpContext.Response.Body.Write(buffer, 0, length);
						WebUtil.HttpContext.Response.Body.Flush();
						WebUtil.HttpContext.Response.Clear();
						dataToRead -= length;
					}
					else
					{
						dataToRead = -1; //防止client失去连接 
					}
				}
			}
			catch (Exception ex)
			{
				//WebUtil.HttpContext.Response.Body.Write("Error:" + ex.Message);
			}
			finally
			{
				if (stream != null) stream.Close();
				WebUtil.HttpContext.Response.Body.Close();
			}
		}
		//	/// <summary>
		//	///  输出硬盘文件，提供下载 支持大文件、续传、速度限制、资源占用小
		//	/// </summary>
		//	/// <param name="_Request">Page.Request对象</param>
		//	/// <param name="_Response">Page.Response对象</param>
		//	/// <param name="_fileName">下载文件名</param>
		//	/// <param name="_fullPath">带文件名下载路径</param>
		//	/// <param name="_speed">每秒允许下载的字节数</param>
		//	/// <returns>返回是否成功</returns>
		//	//---------------------------------------------------------------------
		//	//调用：
		//	// string FullPath=Server.MapPath("count.txt");
		//	// ResponseFile(this.Request,this.Response,"count.txt",FullPath,100);
		//	//---------------------------------------------------------------------
		//       public static bool ResponseFile(HttpContext _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
		//       {
		//           try
		//           {
		//               FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
		//               BinaryReader br = new BinaryReader(myFile);
		//               try
		//               {
		//                   _Response.AddHeader("Accept-Ranges", "bytes");
		//                   _Response.Buffer = false;

		//                   long fileLength = myFile.Length;
		//                   long startBytes = 0;
		//                   int pack = 10240;  //10K bytes
		//                   int sleep = (int)Math.Floor((double)(1000 * pack / _speed)) + 1;

		//                   if (_Request.Headers["Range"] != null)
		//                   {
		//                       _Response.StatusCode = 206;
		//                       string[] range = _Request.Headers["Range"].Split(new char[] { '=', '-' });
		//                       startBytes = Convert.ToInt64(range[1]);
		//                   }
		//                   _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
		//                   if (startBytes != 0)
		//                   {
		//                       _Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
		//                   }

		//                   _Response.AddHeader("Connection", "Keep-Alive");
		//                   _Response.ContentType = "application/octet-stream";
		//                   _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

		//                   br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
		//                   int maxCount = (int)Math.Floor((double)((fileLength - startBytes) / pack)) + 1;

		//                   for (int i = 0; i < maxCount; i++)
		//                   {
		//                       if (_Response.IsClientConnected)
		//                       {
		//                           _Response.BinaryWrite(br.ReadBytes(pack));
		//                           Thread.Sleep(sleep);
		//                       }
		//                       else
		//                       {
		//                           i = maxCount;
		//                       }
		//                   }
		//               }
		//               catch
		//               {
		//                   return false;
		//               }
		//               finally
		//               {
		//                   br.Close();
		//                   myFile.Close();
		//               }
		//           }
		//           catch
		//           {
		//               return false;
		//           }
		//           return true;
		//       }
	}
}