package book.upload;

import java.io.*;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.*;

import org.apache.commons.fileupload.*;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadServlet extends HttpServlet {

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws IOException, ServletException {
        //創建HttpSession對象
		HttpSession session = request.getSession();

		if ("status".equals(request.getParameter("c"))) {//如果請求中c的值為status
			doStatus(session, response);//調用doStatus方法
		} else {//否則，調用doFileUpload方法
			doFileUpload(session, request, response);
		}
	}

	public void processUploadedFile(FileItem item) {
		//獲得上傳文件的文件名
		String fileName = item.getName().substring(item.getName().lastIndexOf("\\") + 1);
		//創建File對象,將上傳得文件保存到C:\\upload文件夾下
		File file = new File("C:\\upload\\", fileName);
		InputStream in;
		try {
			in = item.getInputStream();//獲得輸入數據流文件
			//將該數據流寫入到指定文件中
			FileOutputStream out = new FileOutputStream(file);
			byte[] buffer = new byte[4096]; // To hold file contents
			int bytes_read;
			while ((bytes_read = in.read(buffer)) != -1) // Read until EOF
			{
				out.write(buffer, 0, bytes_read);
			}
			if (in != null)
				try {
					in.close();
				} catch (IOException e) {
					;
				}
			if (out != null)
				try {
					out.close();
				} catch (IOException e) {
					;
				}
		} catch (IOException e1) {
			e1.printStackTrace();
		}
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws IOException, ServletException {
		doPost(request, response);
	}

	private void doFileUpload(HttpSession session, HttpServletRequest request,
			HttpServletResponse response) throws IOException {
		try {
			//創建UploadListener對象
			UploadListener listener = new UploadListener(request.getContentLength());
			listener.start();//啟動監聽狀態
			//將監聽器對象的狀態保存在Session中
			session.setAttribute("FILE_UPLOAD_STATS", listener.getFileUploadStats());
			//創建MonitoredDiskFileItemFactory對象
			FileItemFactory factory = new MonitoredDiskFileItemFactory(listener);
			//通過該工廠對象創建ServletFileUpload對象
			ServletFileUpload upload = new ServletFileUpload(factory);
			//將轉化請求保存到list對象中
			List items = upload.parseRequest(request);
			//停止使用監聽器
			listener.done();
			boolean hasError = false;
			//循環list中的對象
			for (Iterator i = items.iterator(); i.hasNext();) {
				FileItem fileItem = (FileItem) i.next();
				if (!fileItem.isFormField()) {//如果該FileItem不是表單域
					processUploadedFile(fileItem);//調用processUploadedFile方法,將數據保存到文件中
					fileItem.delete();//內存中刪除該數據流
				}
			}

			if (!hasError) {//如果沒有出現錯誤
				sendCompleteResponse(response, null);//調用sendCompleteResponse方法
			} else {
				sendCompleteResponse(response,
						"Could not process uploaded file. Please see log for details.");
			}
		} catch (Exception e) {
			sendCompleteResponse(response, e.getMessage());
		}
	}

	private void doStatus(HttpSession session, HttpServletResponse response)
			throws IOException {
		// 設置該響應不在緩存中讀取
		response.addHeader("Expires", "0");
		response.addHeader("Cache-Control",
				"no-store, no-cache, must-revalidate");
		response.addHeader("Cache-Control", "post-check=0, pre-check=0");
		response.addHeader("Pragma", "no-cache");
        //獲得保存在Session中的狀態信息
		UploadListener.FileUploadStats fileUploadStats = (UploadListener.FileUploadStats) session.getAttribute("FILE_UPLOAD_STATS");
		if (fileUploadStats != null) {
			long bytesProcessed = fileUploadStats.getBytesRead();//獲得已經上傳的數據大小
			long sizeTotal = fileUploadStats.getTotalSize();//獲得上傳文件的總大小
			//計算上傳完成的百分比
			long percentComplete = (long) Math.floor(((double) bytesProcessed / (double) sizeTotal) * 100.0);
			//獲得上傳已用的時間
			long timeInSeconds = fileUploadStats.getElapsedTimeInSeconds();
			//計算平均上傳速率
			double uploadRate = bytesProcessed / (timeInSeconds + 0.00001);
			// 計算總共所需時間
			double estimatedRuntime = sizeTotal / (uploadRate + 0.00001);
            //將上傳狀態返回給客戶端
			response.getWriter().println("<b>Upload Status:</b><br/>");
			if (fileUploadStats.getBytesRead() != fileUploadStats.getTotalSize()) {
				response.getWriter().println(
						"<div class=\"prog-border\"><div class=\"prog-bar\" style=\"width: "
								+ percentComplete + "%;\"></div></div>");
				response.getWriter().println(
						"Uploaded: " + bytesProcessed + " out of " + sizeTotal
								+ " bytes (" + percentComplete + "%) "
								+ (long) Math.round(uploadRate / 1024)
								+ " Kbs <br/>");
				response.getWriter().println(
						"Runtime: " + formatTime(timeInSeconds) + " out of "
								+ formatTime(estimatedRuntime) + " "
								+ formatTime(estimatedRuntime - timeInSeconds)
								+ " remaining <br/>");
			} else {
				response.getWriter().println(
						"Uploaded: " + bytesProcessed + " out of " + sizeTotal
								+ " bytes<br/>");
				response.getWriter().println("Complete.<br/>");
			}
		}
        //如果文件已經上傳完畢
		if (fileUploadStats != null&& fileUploadStats.getBytesRead() == fileUploadStats.getTotalSize()) {
			response.getWriter().println("<b>Upload complete.</b>");
		}
	}

	private void sendCompleteResponse(HttpServletResponse response,
			String message) throws IOException {
		if (message == null) {
			response.getOutputStream().print("<html><head><script type='text/javascript'>function killUpdate() { window.parent.killUpdate(''); }</script></head><body onload='killUpdate()'></body></html>");
		} else {
			response.getOutputStream().print("<html><head><script type='text/javascript'>function killUpdate() { window.parent.killUpdate('"
									+ message+ "'); }</script></head><body onload='killUpdate()'></body></html>");
		}
	}

	private String formatTime(double timeInSeconds) {
		long seconds = (long) Math.floor(timeInSeconds);
		long minutes = (long) Math.floor(timeInSeconds / 60.0);
		long hours = (long) Math.floor(minutes / 60.0);

		if (hours != 0) {
			return hours + "hours " + (minutes % 60) + "minutes "
					+ (seconds % 60) + "seconds";
		} else if (minutes % 60 != 0) {
			return (minutes % 60) + "minutes " + (seconds % 60) + "seconds";
		} else {
			return (seconds % 60) + " seconds";
		}
	}
}