package utils;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * Filters used to make SQL injection more difficult to perform <br>
 * <br>
 * This file is part of the Security Shepherd Project.
 *
 * <p>The Security Shepherd project is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software Foundation, either
 * version 3 of the License, or (at your option) any later version.<br>
 *
 * <p>The Security Shepherd project is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details.<br>
 *
 * <p>You should have received a copy of the GNU General Public License along with the Security
 * Shepherd project. If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Mark Denihan
 */
public class SqlFilter {

  private static final Logger log = LogManager.getLogger(SqlFilter.class);

  public static String levelFour(String input) {
    input = input.toLowerCase();
    while (input.contains("'")) {
      log.debug("Scrubbing ' from input");
      input = input.replaceAll("'", "");
    }
    return input;
  }

  public static String levelOne(String input) {
    log.debug("Filtering input at SQL levelOne");
    return input.replaceFirst("'", "");
  }

  public static String levelThree(String input) {
    log.debug("Filtering input at SQL levelThree");
    input = input.toLowerCase();
    input =
        input
            .replaceAll("|", "")
            .replaceAll("&", "")
            .replaceAll("!", "")
            .replaceAll("-", "")
            .replaceAll(";", "");
    while (input.contains("or")
        || input.contains("true")
        || input.contains("false")
        || input.contains("and")
        || input.contains("is")) {
      input =
          input
              .replaceAll("or", "")
              .replaceAll("true", "")
              .replaceAll("and", "")
              .replaceAll("false", "")
              .replaceAll("is", "");
    }
    return input;
  }

  public static String levelTwo(String input) {
    log.debug("Filtering input at SQL levelTwo");
    input = input.replaceAll("OR", "").replaceAll("or", "");
    input = input.replaceAll("OR", "").replaceAll("or", "");
    input = input.replaceAll("|", "").replaceAll("&", "");
    input = input.replaceAll("true", "").replaceAll("TRUE", "");
    return input;
  }
}