package org.apache.helix.util;
   
   /*
    * 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.
   */
  
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.log4j.Logger;
  
  public class StringTemplate
  {
    private static Logger LOG = Logger.getLogger(StringTemplate.class);
  
    Map<Enum, Map<Integer, String>> templateMap = new HashMap<Enum, Map<Integer, String>>();
    static Pattern pattern = Pattern.compile("(\\{.+?\\})");
  
    public void addEntry(Enum type, int numKeys, String template)
    {
      if (!templateMap.containsKey(type))
      {
        templateMap.put(type, new HashMap<Integer, String>());
      }
      LOG.trace("Add template for type: " + type.name() + ", arguments: " + numKeys
          + ", template: " + template);
      templateMap.get(type).put(numKeys, template);
    }
  
    public String instantiate(Enum type, String... keys)
    {
      if (keys == null)
      {
        keys = new String[] {};
      }
  
      String template = null;
      if (templateMap.containsKey(type))
      {
        template = templateMap.get(type).get(keys.length);
      }
  
      String result = null;
  
      if (template != null)
      {
        result = template;
        Matcher matcher = pattern.matcher(template);
        int count = 0;
        while (matcher.find())
        {
          String var = matcher.group();
          result = result.replace(var, keys[count]);
          count++;
        }
      }
  
      if (result == null || result.indexOf('{') > -1 || result.indexOf('}') > -1)
      {
        String errMsg = "Unable to instantiate template: " + template
            + " using keys: " + Arrays.toString(keys);
        LOG.error(errMsg);
        throw new IllegalArgumentException(errMsg);
      }
  
      return result;
    }
  
  }