package info;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
import javax.sql.DataSource;

public class manage extends HttpServlet {
  private static final String CONTENT_TYPE = "text/html; charset=GB2312";
  private DataSource dataSource=null;
  //Initialize global variables
  public void init() throws ServletException {
    dataSource=LinkDB.getDB();
  }
  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType(CONTENT_TYPE);
    request.setCharacterEncoding("GB2312");
    PrintWriter out = response.getWriter();
    HttpSession session=request.getSession(true);
    String username=(String)session.getAttribute("supername");
    if(username==null){
      out.println("<script>alert('你沒有管理員權限');self.close();</script>");
      return;
    }
    String action=request.getParameter("action");
    String id=request.getParameter("id");
    if(action==null||id==null){
      out.println("<script>alert('請指定條件');self.close();</script>");
      return;
    }
    Connection conn=null;
    Statement stmt=null;
    try{
      conn=dataSource.getConnection();
      stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
      if (action.equals("change")) {
        ReadDB readDB=new ReadDB();
        out.println("<form action=manage method=post>");
        for(int i=1;i<=readDB.getNum()-2;i++){
          out.println("課程"+i+"：<input type=text name=class"+i+"><br>");
        }
        out.println("<input type=hidden name=num value="+readDB.getNum()+">");
        out.println("<input type=hidden name=id value="+id+">");
        out.println("<input type=submit value='確定'>");
        out.println("</form>");
      }
      else if (action.equals("del")) {
        int result=stmt.executeUpdate("delete from info_table1 where id='"+id+"'");
        if(result==0){
          out.println("<script>alert('刪除失敗');self.close();</script>");
        }
        else{
          out.println("<script>alert('刪除成功');self.close();</script>");
        }
      }
      else {
        out.println("<script>alert('請指定條件');self.close();</script>");
      }
    }
    catch(SQLException e){
      out.println(e);
    }
    finally{
      try {
        stmt.close();
        conn.close();
        LinkDB.shutdownDataSource(dataSource);
      }
      catch (SQLException e) {
        out.println(e);
      }
    }
  }
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType(CONTENT_TYPE);
    request.setCharacterEncoding("GB2312");
    PrintWriter out = response.getWriter();
    Connection conn=null;
    Statement stmt=null;
    float[] classname;
    String id=request.getParameter("id");
    try{
      int num=Integer.parseInt(request.getParameter("num"));
      classname=new float[num-2];
      for(int i=1;i<=num-2;i++){
        classname[i-1]=Float.parseFloat(request.getParameter("class"+i));
      }
    }
    catch(NumberFormatException e){
      out.println("<script>alert('成績必須為實數');document.location='javascript:history.go(-1);'</script>");
      return;
    }
    try{
      conn=dataSource.getConnection();
      stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
      String sql="update info_table2 set ";
      for(int i=1;i<=classname.length;i++){
        if(i==classname.length){
          sql = sql + "class" + i + "=" + classname[i - 1] ;
        }
        else{
          sql = sql + "class" + i + "=" + classname[i - 1] + ",";
        }
      }
      sql=sql+" where id='"+id+"'";
      int result=stmt.executeUpdate(sql);
      if(result==0){
        out.println("<script>alert('修改失敗');self.close();</script>");
      }
      else{
        out.println("<script>alert('修改成功');self.close();</script>");
      }
    }
    catch(SQLException e){
      out.println(e);
    }
    finally{
      try {
        stmt.close();
        conn.close();
        LinkDB.shutdownDataSource(dataSource);
      }
      catch (SQLException e) {
        out.println(e);
      }
    }
  }
}