WAD-hw1

import java.sql.Statement;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet(urlPatterns = {"/registrationController"})
public class registrationController extends HttpServlet {

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     * @throws java.sql.SQLException
     */
    public boolean userExists(String username) throws SQLException{
    try{

        String url="jdbc:derby://localhost:1527/a";
        Connection con=DriverManager.getConnection(url,"a","a");
        String sql="SELECT * FROM A.users";
        Statement instr = con.createStatement();
        ResultSet rs= instr.executeQuery(sql);
        while(rs.next()){
        String name=rs.getString("username");
        if(name.compareTo(username)==0) return true;
        }
        } catch (SQLException ex){
            ex.printStackTrace();
        }
        return false;
    }
    public static String getHash(String password) {
        MessageDigest digest=null;
        try {
        digest = MessageDigest.getInstance("SHA-1");
        } catch (NoSuchAlgorithmException ex) {
        ex.printStackTrace();
        }
        digest.reset();
        try {
        digest.update(password.getBytes("UTF-8"));
        } catch (UnsupportedEncodingException ex) {
        ex.printStackTrace();
        }
        return new BigInteger(1, digest.digest()).toString(16);
    }
    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, SQLException {
        response.setContentType("text/html;charset=UTF-8");
        String username = request.getParameter("username");
        if(userExists(username)) {
            getServletContext().getRequestDispatcher("/index.jsp").forward(request, response);
        }
        else
        try (PrintWriter out = response.getWriter()) {
            out.println("<html>\n" +
                        "    <head>\n" +
                        "        <link rel=\"stylesheet\" href=\"style.css\" type=\"text/css\"/>\n" +
                        "        <script type=\"text/javascript\" src=\"js/jquery-1.11.0.js\"></script>\n" +
                        "        <script type=\"text/javascript\" src=\"js/register.js\"></script> \n" +
                        "        <title>Registration</title>\n" +
                        "        <meta charset=\"UTF-8\">\n" +
                        "        <meta name=\"viewport\" content=\"width=device-width\">\n" +
                        "    </head> <body>\n" +
                        "        <div id=\"content\">\n" +
                        "        <div class=\"header\">\n" +
                        "            <img src=\"./img/companyLogo.jpg\" width=\"100px\"  />\n" +
                        "            <span class=\"header-text\">Fane & Company</span>\n" +
                        "        </div> </body> </html>");

            Set<String> params=request.getParameterMap().keySet();
            String url="jdbc:derby://localhost:1527/a";
            Connection con=DriverManager.getConnection(url,"a","a");
            String query = "INSERT INTO USERS " + "VALUES(?,?,?,?,?,?,?)";
            PreparedStatement statement = con.prepareStatement(query);
            String pass=getHash(request.getParameter("password"));
            statement.setString(1,request.getParameter("name"));
            statement.setString(2,request.getParameter("username"));
            statement.setString(3,request.getParameter("password"));
            statement.setString(4,request.getParameter("email"));
            statement.setString(5,request.getParameter("gender"));
            statement.setString(6,request.getParameter("telephone"));
            statement.setString(7,request.getParameter("country"));
            statement.execute();
            for(String s : params){
                out.println("<p>Parameter "+s+" has the value "+request.getParameter(s));
            }
        }

    }