content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.ambari.server.upgrade;
  
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.springframework.util.StringUtils;
  
  public class SchemaUpgradeUtil {
  
    private SchemaUpgradeUtil() {
      throw new UnsupportedOperationException();
    }
  
    /**
     * Extracts a new property that was introduced to make a content type property more configurable by making a hard coded value
     * changeable. The function takes a pattern to identify the previous value of the property, and replaces the actual value with
     * a reference to the new property, and also adds the new property to a map.
     * 
     * Example:
     * content: ... some.variable=HARDCODED_VALUE ...
     * propertyName: some_variable
     * variableName: some_variable_processed
     * propertyPattern: some.variable=(\w)
     * 
     * the function returns: ... some.variable={{some_variable_processed}}
     * newProperties will contain: some_variable -> HARDCODED_VALUE
     * 
     * @param content the content type variable's content before upgrade
     * @param propertyName the name of the new property
     * @param variableName the name of the variable that will be used in the content
     * @param propertyPattern the regexp pattern to identify the property, must contain exactly one "(\w+)" for the actual value of
     *                        the new property
     * @param defaultValue the default value for the new property if the actual value can not be found in the content
     * @param newProperties map of new properties where the extracted property will be put
     * @return the updated content containing a reference to the new property
     */
    public static String extractProperty(String content, String propertyName, String variableName, String propertyPattern,
        String defaultValue, Map<String, String> newProperties) {
      if (StringUtils.countOccurrencesOf(propertyPattern, "(\\w+)") != 1) {
        throw new IllegalArgumentException("propertyPattern must contain exactly one '(\\w+)': " + propertyPattern);
      }
      
      Pattern p = Pattern.compile(propertyPattern);
      Matcher m = p.matcher(content);
      
      String propertyValue = defaultValue;
      if (m.find()) {
        propertyValue = m.group(1);
        
        String unescapedPattern = propertyPattern.replace("\\{", "{");
        String toReplace = unescapedPattern.replace("(\\w+)", propertyValue);
        String replaceWith = unescapedPattern.replace("(\\w+)", "{{" + variableName + "}}");
        content = content.replace(toReplace, replaceWith);
      }
      newProperties.put(propertyName, propertyValue);
      return content;
    }
  }
  