/**
 * This class is used to display all database tables to the
 * user in the form of an HTML form drop-down (select) field, so that the
 * user can choose which one they want to administer. It also displays a 
 * drop down box that asks the user to select which catalog they want to use
 * and several radio buttons to choose which operation they want to perform
 */

package admin;

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

import utilities.*;

public class PresentMenu extends HttpServlet
{
        /**
         * if an error occurs such as not logged in redirect to this error page for now set for the login page
         */
        private String errorTarget = "../admin/index.jsp";

	/**
         * used to initialize the servlet
         */
        public void init(ServletConfig config) throws ServletException
        {
                super.init(config);
        }

	/**
         * all get requests are forwarded to doPost()
         */
        public void doGet(HttpServletRequest request,
                          HttpServletResponse response)
                          throws ServletException, IOException
        {

                // If it is a get request forward to doPost()
                doPost(request, response);
        }

	/**
	 * This method does all the work
	 */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                                throws ServletException, IOException
        {
                Connection conn=null;
                ResultSet tableSet=null;

                //name of the user
                String name="";

                PrintWriter out = response.getWriter();
                response.setContentType("text/html");

                //first thing that every servlet or jsp should do is check if user is logged in
                HttpSession session = request.getSession(false);

                //if not logged in redirect to login
                if(session == null)
                {
                        HTMLUtils.printRedirectPage(out, "You must login to the system prior to viewing this page.", errorTarget);
                        return;
                }

                //else if logged in take the name from the session
                else
                {
                        name=(String)session.getAttribute("user");

                        //if the name is null
                        if(name == null)
                        {
                                HTMLUtils.printRedirectPage(out, "You must login to the system prior to viewing this page.", errorTarget);
                                return;
                        }

                }

                //second output the Admin Header
                HTMLUtils.printAdminHeader(out);

                //display welcome message to the user
                out.println("<p align=left>Welcome " + name + "</p>");


                String html="<form method=post action=admin.TableDisplay><p align=center><select name=table>";

                out.println("<p align=center>Please select the Catalog you would like to administer:<br>");
                out.println("<select name=catalog><option value='Ug_Catalog_2002-2003'>2002-2003</option></select>");

                out.println("<p align=center>Please select what information you would like to administer:<br>");

                html= html + "<select name=table>";

                try
                {
                        conn = MyConnection.open();

                        //get the list of table names
                        java.sql.DatabaseMetaData dbmd = conn.getMetaData();
                        tableSet = dbmd.getTables(null,null,null,new String[]{"TABLE"});

                        while(tableSet.next())
                        {
                                html= html + "<option value=" + tableSet.getString("TABLE_NAME")+ ">" + tableSet.getString("TABLE_NAME") + "</option>";
                        }

                        tableSet.close();

                }

                catch(SQLException e){System.err.println("SQLException " + e.getMessage());}

                html = html + "</select><br><br>";
                html = html + "<input type=radio name=operation value=View checked=true>View &nbsp;&nbsp;&nbsp;";
                html = html + "<input type=radio name=operation value=Add>Add &nbsp;&nbsp;&nbsp;";
                html = html + "<input type=radio name=operation value=Modify>Modify &nbsp;&nbsp;&nbsp;";
                html = html + "<input type=radio name=operation value=Delete>Delete &nbsp;&nbsp;&nbsp;";
                html = html + "<br><input type=image src='../button_submit.gif' alt=Submit></form>";

                out.println(html);

                HTMLUtils.printAdminFooter(out);
        }
}