package Servleti;

import java.io.IOException;
import java.io.PrintWriter;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.SingleThreadModel;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class LoginServlet extends HttpServlet implements SingleThreadModel
{
    String Upit="";
    String Greska="";
    String KorisnickoIme="";
    String Lozinka="";
    
    Connection con= null;
    Statement stmt= null;
    ResultSet RS= null;
    
    boolean Prazno = false;
    
    ServletContext sc= null;
    RequestDispatcher rd= null;
    
    public void doGet (HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException
    {
        doPost(req, res); // poziva metodu doPost
    }
    
    public void doPost (HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException
    {
        HttpSession session= null;
        session= req.getSession(true);
        sc= getServletContext();
        if (!req.getParameter("KorisnickoIme").equals(""))  // da li je upisano korisnicko ime ?
        {
            KorisnickoIme= req.getParameter("KorisnickoIme");
        } else
        {
            Prazno= true;
            Greska+= "Korisnicko ime nije upisano<br>";
        }
        
        if (!req.getParameter("Lozinka").equals(""))  // da li je upisana lozinka ?
        {
            Lozinka= req.getParameter("Lozinka");
        } else
        {
            Prazno= true;
            Greska+= "Lozinka nije upisana<br>";
        }
        
        try
        {
            session.setAttribute("KorisnickoIme",KorisnickoIme);
            session.setAttribute("Lozinka", Lozinka);
            konektujSe(req, res);
            zatvoriKonekciju();
            pozoviJSP(req, res);
        } catch (Exception e)
        {
            Greska= "Greska! Pokusajte Ponovo";
            proslediGresku(Greska, req, res);
            Greska= "";
        }
    }// kraj doPost Metode
        
        
public void konektujSe(HttpServletRequest req,  HttpServletResponse res)
  {
      try
      {
          Class.forName("sun.oracle.JdbcOdbcDriver").newInstance();
          String url= "oracle.jdbc:thin:@localhost:1521:XE";
          con = DriverManager.getConnection(url,"KorisnickoIme","Lozinka");
          stmt=con.createStatement();
          String Upit = "select * from Korisnici where (Korisnicko_Ime='"+KorisnickoIme+"' and Lozinka='"+Lozinka+"')";
          RS=stmt.executeQuery(Upit);
          if(!RS.next()) 
          {
              Greska="Ne postoji korisnik sa unetim korisnickim imenom i sifrom!";
        proslediGresku(Greska,req,res);
      }
      } catch (Exception e)
      {
            //e.printStackTrase();
          Greska= "Konekcija sa bazom nije uspostavljena";
          proslediGresku(Greska, req, res);
          Greska= "";
      }
  }
  
  public void zatvoriKonekciju ()
  {
    if (con!=null)
    {
        try
        {
            con.close();
        } catch (SQLException e)
        {
            Greska= "Greska prilikom zatvaranja veze sa bazom podataka";
            Greska= "";
        }
    } // kraj metode zatvoriKonekciju
  }
  public void proslediGresku(String g, HttpServletRequest req, HttpServletResponse res)
    {
        HttpSession session=null;
        session= req.getSession(true);
        session.setAttribute("Greska", Greska);
        rd = sc.getRequestDispatcher("/Greska.jsp");
        try
        {
            rd.forward(req, res);
            Greska= "";
        } catch (Exception e)
        {
        }
    } // kraj metode proslediGresku

public void pozoviJSP (HttpServletRequest req, HttpServletResponse res)
  {
      try
      {
          rd = sc.getRequestDispatcher("/FizickaL.jsp");
          rd.forward(req, res);
      } catch (Exception e)
      {
          Greska = "Nije Uspelo "+e;
          proslediGresku(Greska, req, res);
          Greska= "";
      }        
  } //kraj metode pozoviJSP

}