package coreservlets;

import javax.servlet.*;
import javax.servlet.http.*;

/** <P>
 *  Taken from Core Servlets and JavaServer Pages Volume II
 *  from Prentice Hall and Sun Microsystems Press,
 *  http://volume2.coreservlets.com/.
 *  (C) 2007 Marty Hall, Larry Brown, and Yaakov Chaikin;
 *  may be freely used or adapted.
 */

public class ServletUtilities {
  public static final String DOCTYPE =
    "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
    "Transitional//EN\">";

  public static String headWithTitle(String title) {
    return(DOCTYPE + "\n" +
           "<HTML>\n" +
           "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n");
  }

  public static int getIntParameter(HttpServletRequest request,
                                    String paramName,
                                    int defaultValue) {
    String paramString = request.getParameter(paramName);
    int paramValue;
    try {
      paramValue = Integer.parseInt(paramString);
    } catch(NumberFormatException nfe) { // null albo zły format
      paramValue = defaultValue;
    }
    return(paramValue);
  }

  public static String getCookieValue(Cookie[] cookies,
                                      String cookieName,
                                      String defaultValue) {
    if (cookies != null) {
      for(int i=0; i<cookies.length; i++) {
        Cookie cookie = cookies[i];
        if (cookieName.equals(cookie.getName()))
          return(cookie.getValue());
      }
    }
    return(defaultValue);
  }


  public static Cookie getCookie(Cookie[] cookies,
                                 String cookieName) {
    if (cookies != null) {
      for(int i=0; i<cookies.length; i++) {
        Cookie cookie = cookies[i];
        if (cookieName.equals(cookie.getName()))
          return(cookie);
      }
    }
    return(null);
  }

  public static String filter(String input) {
    StringBuffer filtered = new StringBuffer(input.length());
    char c;
    for(int i=0; i<input.length(); i++) {
      c = input.charAt(i);
      if (c == '<') {
        filtered.append("&lt;");
      } else if (c == '>') {
        filtered.append("&gt;");
      } else if (c == '"') {
        filtered.append("&quot;");
      } else if (c == '&') {
        filtered.append("&amp;");
      } else {
        filtered.append(c);
      }
    }
    return(filtered.toString());
  }
}
