Copyright (C) 2010 the original author or authors.
See the notice.md file distributed with this work for additional
information regarding copyright ownership.
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.
/**
 * Copyright (C) 2010 the original author or authors.
 * See the notice.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * 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 com.beust.jcommander.defaultprovider;

import com.beust.jcommander.IDefaultProvider;
import com.beust.jcommander.ParameterException;

import java.io.IOException;
import java.net.URL;
import java.util.Properties;

A default provider that reads its default values from a property file.
Author:
cbeust/**
 * A default provider that reads its default values from a property file.
 * 
 * @author cbeust
 */
public class PropertyFileDefaultProvider implements IDefaultProvider {
  public static final String DEFAULT_FILE_NAME = "jcommander.properties";
  private Properties properties;

  public PropertyFileDefaultProvider() {
    init(DEFAULT_FILE_NAME);
  }

  public PropertyFileDefaultProvider(String fileName) {
    init(fileName);
  }

  private void init(String fileName) {
    try {
      properties = new Properties();
      URL url = ClassLoader.getSystemResource(fileName);
      if (url != null) {
        properties.load(url.openStream());
      } else {
        throw new ParameterException("Could not find property file: " + fileName
            + " on the class path");
      }
    }
    catch (IOException e) {
      throw new ParameterException("Could not open property file: " + fileName);
    }
  }
  
  public String getDefaultValueFor(String optionName) {
    int index = 0;
    while (index < optionName.length() && ! Character.isLetterOrDigit(optionName.charAt(index))) {
      index++;
    }
    String key = optionName.substring(index);
    return properties.getProperty(key);
  }

}