package cy99xfq.myServlet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.util.*;
import cy99xfq.myServlet.myDatabase;

/**
 * ImageDBServlet.java
 * 
 * This servlet demonstrates how to use JDBC driver to access the 
 * image database from the servlet, thus shows a 3-tier JDBC example.
 *
 * @author xjqiu@npac.syr.edu 
 */


public class ImageDBServlet extends HttpServlet {

    String imgname;
	String color; 
	String type; 
    String url;
   	String noneLabel=" "; 

	/**
     * doGet() method
     * At Server side, collection query information from client side interface,
     * access Image Database, send back HTML file containing query results
     */
    public void doGet(HttpServletRequest req, HttpServletResponse res) 
        throws ServletException, IOException
    {
               
	Connection con;
	PrintWriter out;

	res.setContentType("text/html");
	out = new PrintWriter(res.getOutputStream());
	
//  Fetch the parameters from client side
//  while checking each field of the query table.
//  Perform Database Access according to the value combinations provieded from User.

    if (req.getParameter("imgname") != null) 
		imgname=req.getParameter("imgname");
	else
		imgname=noneLabel;

    if (req.getParameter("color") != null) 
		color=req.getParameter("color");
	else
		color=noneLabel;

    if (req.getParameter("type") != null) 
		type=req.getParameter("type");
	else
		type=noneLabel;

    if (req.getParameter("url") != null) 
		url=req.getParameter("url");
	else
		url=noneLabel;


	printPageHeader(out); 
	
    String cntrl = req.getParameter("control");
    if(cntrl != null) {
        if (cntrl.equals("Search")) {//Search button pressed
    	      doSearch(req, out);
        }else if (cntrl.equals("Insert")) {//Insert button pressed
    	      doInsert(out);
        }
    }    

	printPageFooter(out);	
}



	private String getSQLstring(HttpServletRequest req) {
     	String tmpstr = "select * from images_table where ";
     	StringBuffer strbuf = new StringBuffer();

     	if(!(imgname.trim().equals(""))) { 
     		strbuf.append("upper(imgname)=upper('"+(req.getParameter("imgname")).trim()+"') and ");
		}else {
			strbuf.append("imgname like '%' and ");
		}


     	if(!(color.trim().equals(""))) { 
     		strbuf.append("upper(color)=upper('"+(req.getParameter("color")).trim()+"') and ");
		}else {
			strbuf.append("color like '%' and ");
		}


     	if(!(type.trim().equals(""))) { 
     		strbuf.append("upper(type)=upper('"+(req.getParameter("type")).trim()+"') and ");
		}else {
			strbuf.append("type like '%' and ");
		}

     	if(!(url.trim().equals(""))) { 
     		strbuf.append("upper(url)=upper('"+(req.getParameter("url")).trim()+"');");
		}else {
			strbuf.append("url like '%'");
		}


     	tmpstr = tmpstr + strbuf.toString();
     	if(tmpstr == null || tmpstr.equals("") ) return noneLabel;
     	else return tmpstr;
 	}




 private void doInsert() { //Insert new record to database file

        String sql = "insert into images_table values(" +
                     "images_table_seq.nextval,'"+imgname+
                     "','"+color+"','"+type+"','"+
                     url+"')";

        myDatabase myDb = new myDatabase();
        myDb.open();

        myDb.executeSQL(sql);
        myDb.close();

        out.println("New record has been added to Database!");
    }




	private void doSearch(HttpServletRequest req, PrintWriter out) {

		String sql;

		sql = getSQLstring(req);


		myDatabase myDb = new myDatabase();
        myDb.open();

        Vector vec = myDb.getRecords(sql);
        Hashtable ht ;

		 
        if(vec.size() <= 0) {
            out.println("<center><b> No Records Matched the Query !</b></center>");
        }else {
			out.println("<center>");
			out.println("<table width=\"90%\">");

	   	    for(Enumeration e = vec.elements(); e.hasMoreElements(); ){
				ht = (Hashtable) e.nextElement();
    	        displayHashtable(ht,out);
        	}
		
			myDb.close();
			out.println("</table>");
			out.println("</center>");
		}

    } 


 	private String get(String key, Hashtable ht){ //Check keyword field, subsitute null field with " " 
     	if(ht.get(key) != null) 
         	return ht.get(key).toString();
     	else
         	return " ";
 	}

}//end of class