package com.course;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class CourseSvlt extends HttpServlet{
	 //響應get請求
public void doGet(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {
	//獲得課程ID
    String cour_id =req.getParameter("id");
    int success = 0;
    //獲取請求中的參數
    String action = action = req.getParameter("action");
    course cour = null;
    String message="";
    //如果請求中包含新建課程參數
    if ("new".equalsIgnoreCase(action)) {
        //調用新建課程方法
    	cour = doNew(req,res);
    	 //并將新建課程存儲在request上下文中，然后轉向getcourse.jsp頁面
      sendBean(req, res, cour, "/getcourse.jsp");
    }  
    //如果請求中包含更新課程參數
    if ("update".equalsIgnoreCase(action)) {
    	try{
    	// 調用更新課程方法	
     	cour = doUpdate(req,res, cour_id);
        //并將更新后的課程存儲在request上下文中，然后轉向getcourse.jsp頁面
     	sendBean(req,res,cour,"/getcourse.jsp");
     	   }
     	  catch(SQLException e){} 
    }
     //如果請求中包含刪除課程參數		   
    if ("delete".equalsIgnoreCase(action)) {
    	try{
    	//調用刪除課程方法
      	success = doDelete(cour_id);	
      	    }
      	    catch(SQLException e){}				
    	if (success != 1) {
    		doError(req, res, "CourseSvlt: Delete unsuccessful. Rows affected: " + success);
    	} else {
    		res.sendRedirect("http://localhost:8080/test/getcourse.jsp");
    	}}
       
    }
    
 //新建課程方法定義   
 public course doNew(HttpServletRequest req,HttpServletResponse res )
                           throws ServletException,IOException{
      course cour= new course();                     	
      String cour_id=req.getParameter("id");
      int mark;
      String name=new String(req.getParameter("name").getBytes("ISO8859_1"));
      try{
      mark= Integer.parseInt(req.getParameter("mark"));
        }catch(NumberFormatException e){mark=0;}
      String dep=new String (req.getParameter("dep").getBytes("ISO8859_1"));
      String prepare =req.getParameter("prepare");
      if(isTrue(req,res,cour_id,name) && hasLogin(req,res,cour_id) && isCompare(prepare,dep,req,res)){
    
      cour.setId(cour_id);
      cour.setName(name);   
      cour.setDep(dep);
      cour.setPrepare(prepare);
      cour.setMark(mark);
      cour.addCourse();
       }  
      return cour;                	
                           	
                           	}
   //判斷課程是否與其預修課屬于同一個系                        	
   public boolean isCompare(String prepare,String dep,
   HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException{
   	   boolean f=true;
   	   String tempDep=null;
   	   String message=null;
   	   course cour= new course();
   	  if( !prepare.equalsIgnoreCase("0")  ){
      tempDep=cour.getPrepareDep(prepare)	;
      if(tempDep.equals("public"))
      return true;
      if(dep.equalsIgnoreCase(tempDep))
       f=true;
      else {
      	f=false;      
      	message="錯誤，課程所在系與預修課所在系不一致！";
      	doError(req,res,message);
      }} 
      return f; 
   	  }                     	
                           	
   //更新課程信息                        	
  public course doUpdate(HttpServletRequest req,HttpServletResponse res , String id)
                           throws ServletException,IOException,SQLException {                      	
    course cour = new course();   
    String name=new String(req.getParameter("name").getBytes("ISO8859_1"));  
     int mark   = Integer.parseInt(req.getParameter("mark"));          
      
    String dep = req.getParameter("dep");
    String prepare = req.getParameter("prepare");
 
    if(isTrue(req,res,id,name) && isCompare(prepare,dep,req,res)){

    cour.setName(name);
    cour.setMark(mark);
    cour.setDep(dep);
    cour.setPrepare(prepare);

    cour.updateCourse(id);}
		return cour;
  }
    //刪除課程
    public int doDelete(String id) throws SQLException {
  	int num=0;
    course cour=new course();
    num=cour.deleteCourse(id);
    return num;
  }
  //保存課程信息的JavaBean到request上下文中
  public void sendBean(HttpServletRequest req, HttpServletResponse res,
                       course cour, String target)
                       throws ServletException, IOException {
    req.setAttribute("cour", cour);
    RequestDispatcher rd = getServletContext().getRequestDispatcher(target);
    rd.forward(req, res);
  } 
    //錯誤處理方法
    public void doError(HttpServletRequest req,
                      HttpServletResponse res,
                      String str)
                      throws ServletException, IOException {


    req.setAttribute("problem", str);
    RequestDispatcher rd = getServletContext().getRequestDispatcher("/errorpage.jsp");
    rd.forward(req, res);
  }
  
    //判斷課程是否被注冊過
    public boolean hasLogin(HttpServletRequest req, HttpServletResponse res,String id)
  throws ServletException, IOException{
  	boolean f=true;
  	String message="對不起，該課程號已經被注冊過了!";
  	course cour= new course();
  	f= cour.hasLogin(id);
  	if(f==false){
  	doError(req,res,message);	
  		}
  		return f;
  	}
  	//判斷課程注冊是否成功
  public boolean isTrue(HttpServletRequest req, HttpServletResponse res,
                        String id,String name)
                        throws ServletException, IOException {
   boolean f=true;                     	
   String message ="";
   if(id==null || id.equals(""))  {
   	f=false;
   	message="錯誤，課程號不能為空！";
   	doError(req,res,message);	}
   
   if(name==null || name.equals(""))  {
   	f=false;
   	message="課程名不能為空，請重新填寫！";
   	doError(req,res,message);	}
  	
     return f;
     
  }
   //響應post請求
    public void doPost(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {

    doGet(req, res);

  }                          	
    
    }