code: /*
   * Copyright © 2014-2017 EntIT Software LLC, a Micro Focus company (L.P.)
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package io.cloudslang.engine.data;
  
  import org.springframework.beans.factory.annotation.Autowired;
  
  import javax.annotation.PostConstruct;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  /**
   * Contains common SQL Utils.
   *
   * User:
   * Date: 03/12/13
   */
  public class SqlUtils {
  
      // Not using '\' since it has special meaning in MySql
      public static final String ESCAPE_CHAR = "~";
      public static final String ESCAPE_EXPRESSION = "escape '" + ESCAPE_CHAR + "'";
  
      private static final String DOUBLE_ESCAPE_CHAR = ESCAPE_CHAR + ESCAPE_CHAR;
  
      private final static String[] NON_MSSQL_SPECIAL_CHARS = {"%", "_"};
  	private final static String[] MSSQL_SPECIAL_CHARS;
  
  	static {
  		List<String> mssqlSpecialCharsList = new ArrayList<>(Arrays.asList(NON_MSSQL_SPECIAL_CHARS));
  		mssqlSpecialCharsList.addAll(Arrays.asList("[","]"));
  		MSSQL_SPECIAL_CHARS = mssqlSpecialCharsList.toArray(new String[mssqlSpecialCharsList.size()]);
  	}
  
  	@Autowired
  	private DataBaseDetector dataBaseDetector;
  
  	// This value is set only once when the Central is up and we don't change our database type
  	// while at least one of the servers is still up, so there's no worry that this value might be worng.
  	private String[] currentSpecialCharsSet;
  
  	@PostConstruct
  	private void setSpecialCharsSet() {
  		currentSpecialCharsSet = dataBaseDetector.isMssql()? MSSQL_SPECIAL_CHARS : NON_MSSQL_SPECIAL_CHARS;
  	}
  
  	/**
  	 * Escaping like expressions so wildcards will not be evaluated.
  	 * The HQL query should have the ESCAPE_EXPRESSION in it's suffix for this to work!!!
  	 *
  	 * The method returns an escaped expression, which would behave the same of all SQL repositories when
  	 * adding escape with the ESCAPE_CHAR to the query.
  	 *
  	 * Note: 'like' expression are evaluated differently in MS-SQL.
  	 * '[]' behaves similar to regex expression and we do handle it specifically in MS-SQL.
  	 * @param likeExpression The like expression to be escaped.
  	 * @return The escaped expression.
  	 */
  	public String escapeLikeExpression(String likeExpression) {
  		String normalizeLikeExpression = likeExpression;
  		if (likeExpression != null && !likeExpression.isEmpty()) {
  			normalizeLikeExpression = normalizeLikeExpression.replace(ESCAPE_CHAR, DOUBLE_ESCAPE_CHAR);
  			for (String charToEscape : currentSpecialCharsSet) {
  				normalizeLikeExpression = normalizeLikeExpression.replace(charToEscape, ESCAPE_CHAR + charToEscape);
  			}
  		}
  		return normalizeLikeExpression;
  	}
  
  	public String normalizeStartingWithLikeExpression(String expression) {
  		return expression + "%";
  	}
  
  	public String normalizeEndingWithLikeExpression(String expression) {
  		return "%" + expression;
  	}
  
  	public String normalizeContainingLikeExpression(String expression) {
  		return "%" + expression + "%";
  	}
  
  }
  