/*******************************************************************************
 *     Cloud Foundry 
 *     Copyright (c) [2009-2016] Pivotal Software, Inc. All Rights Reserved.
 *
 *     This product is licensed to you under the Apache License, Version 2.0 (the "License").
 *     You may not use this product except in compliance with the License.
 *
 *     This product includes a number of subcomponents with
 *     separate copyright notices and license terms. Your use of these
 *     subcomponents is subject to the terms and conditions of the
 *     subcomponent's license, as noted in the LICENSE file.
 *******************************************************************************/
package org.cloudfoundry.identity.uaa.impl.config;

import org.springframework.beans.factory.FactoryBean;

import java.util.Map;
import java.util.Properties;

/**
 * Factory for Java Properties that reads from a YAML source. YAML is a nice
 * human-readable format for configuration,
 * and it has some useful hierarchical properties. It's more or less a superset
 * of JSON, so it has a lot of similar
 * features. The Properties created by this factory have nested paths for
 * hierarchical objects, so for instance this
 * YAML
 * 
 * <pre>
 * environments:
 *   dev:
 *     url: http://dev.bar.com
 *     name: Developer Setup
 *   prod:
 *     url: http://foo.bar.com
 *     name: My Cool App
 * </pre>
 * 
 * is transformed into these Properties:
 * 
 * <pre>
 * environments.dev.url=http://dev.bar.com
 * environments.dev.name=Developer Setup
 * environments.prod.url=http://foo.bar.com
 * environments.prod.name=My Cool App
 * </pre>
 * 
 * Lists are represented as comma-separated values (useful for simple String
 * values) and also as property keys with <code>[]</code> dereferencers, for
 * example this YAML:
 * 
 * <pre>
 * servers:
 * - dev.bar.com
 * - foo.bar.com
 * </pre>
 * 
 * becomes java Properties like this:
 * 
 * <pre>
 * servers=dev.bar.com,foo.bar.com
 * servers[0]=dev.bar.com
 * servers[1]=foo.bar.com
 * </pre>
 * 
 * @author Dave Syer
 * 
 */
public class YamlPropertiesFactoryBean extends YamlProcessor implements FactoryBean<Properties> {

    private Properties instance;

    @Override
    public Properties getObject() {
        if (instance == null) {
            instance = doGetObject();
        }
        return instance;
    }

    private Properties doGetObject() {
        final Properties result = new Properties();
        MatchCallback callback = new MatchCallback() {
            @Override
            public void process(Properties properties, Map<String, Object> map) {
                result.putAll(properties);
            }
        };
        process(callback);
        return result;
    }

    @Override
    public Class<?> getObjectType() {
        return Properties.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

}