package cz.frantovo.sql.vyuka.ajax;

import cz.frantovo.sql.vyuka.dto.Uzivatel;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet pro vyřizování AJAXových požadavků.

 * @author fiki

 */

public class Servlet extends HttpServlet {

    private static final long serialVersionUID = 9102108273105288056L;

    private enum akce {

        /** Provede SQL dotaz. */

        vykonat,

        /** Vypíše historii SQL příkazů daného uživatele. */

        historie,

        /** Nápověda – průvodce */

        napoveda,

        /** Vypíše nějaké nepotřebné informace. */

        test,

        /** Pokud je požadovaná akce nesmysl. */

        chyba

    }

    /** 

     * 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

     */

    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        /** Používáme pouze UTF-8 */

        response.setContentType("text/html;charset=UTF-8");

        request.setCharacterEncoding("UTF-8");

        PrintWriter out = response.getWriter();

        try {

            akce parametrAkce = akce.chyba;

            try {

                parametrAkce = akce.valueOf(request.getParameter("akce"));

            } catch (Exception e) {

                /** Chyba nebo podvržený AJAXový požadavek → zobrazíme chybovou hlášku */

            }

            Ajax a = new Ajax();

            Uzivatel uzivatel = new Uzivatel(request.getRequestedSessionId(), request.getRemoteAddr());

            switch (parametrAkce) {

                case vykonat:

                    out.println(a.geSQLVysledek(request.getParameter("sql"), uzivatel));

                    break;

                case historie:

                    out.println(a.getHistorie(uzivatel));

                    break;

                case napoveda:

                    out.println("<p>Nápověda bude…</p>");

                    break;

                case test:

                    out.println("<p>AJAX jede!</p>");

                    out.println("<ol>");

                    out.println("<li>Metoda: " + request.getMethod() + "</li>");

                    out.println("<li>Host: " + request.getRemoteHost() + "</li>");

                    out.println("<li>Adresa: " + request.getRemoteAddr() + "</li>");

                    out.println("<li>Akce: " + request.getParameter("akce") + "</li>");

                    out.println("<li>SQL: " + request.getParameter("sql") + "</li>");

                    out.println("<li>Sezení: " + request.getRequestedSessionId() + "</li>");

                    out.println("<li>URL: " + request.getRequestURL().toString() + "</li>");

                    out.println("</ol>");

                    break;

                case chyba:

                    out.println("<p>chyba</p>");

                    break;

            }

        } finally {

            out.close();

        }

    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

    /** 

     * Handles the HTTP <code>GET</code> method.

     * @param request servlet request

     * @param response servlet response

     * @throws ServletException if a servlet-specific error occurs

     * @throws IOException if an I/O error occurs

     */

    @Override

    protected void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        processRequest(request, response);

    }

    /** 

     * Handles the HTTP <code>POST</code> method.

     * @param request servlet request

     * @param response servlet response

     * @throws ServletException if a servlet-specific error occurs

     * @throws IOException if an I/O error occurs

     */

    @Override

    protected void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        processRequest(request, response);

    }

    /** 

     * Returns a short description of the servlet.

     * @return a String containing servlet description

     */

    @Override

    public String getServletInfo() {

        return "Servlet pro zpracování AJAXových požadavků.";

    }// </editor-fold>

}