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Configuration Utilities. NOTE: This module is deprecated and will be removed at the end of the v2.x versions of the utilities. Preferred config system after that is either to use true type-safe config with `net.morimekta.providence:providence-config` or to use a simple JSON or YAML library or java properties files. The semi-typesafe layered config did not really solve the problems I had hoped it would, and in essence this was just a helper for merging maps and getting pre-cast values out of it.

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/*
 * Copyright (c) 2016, Stein Eldar Johnsen
 *
 * 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 net.morimekta.config.format;

import net.morimekta.config.Config;
import net.morimekta.config.ConfigException;
import net.morimekta.config.IncompatibleValueException;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Collection;
import java.util.Properties;
import java.util.TreeSet;

import static net.morimekta.config.util.ConfigUtil.asString;

/**
 * Format config into properties objects or files.
 */
public class PropertiesConfigFormatter implements ConfigFormatter {
    @Override
    public void format(Config config, OutputStream out) {
        try {
            Properties properties = format(config);
            properties.store(out, " generated by " + getClass().getName());
        } catch (IOException e) {
            throw new ConfigException(e, e.getMessage());
        }
    }

    /**
     * Format a config into a properties instance.
     *
     * @param config The config to put into the properties instance.
     * @return The properties instance.
     */
    public static Properties format(Config config) {
        Properties properties = new Properties();
        writeConfig("", config, properties);
        return properties;
    }

    // --- INTERNAL ---
    private static void writeConfig(String prefix, Config config, Properties properties) {
        for (String key : new TreeSet<>(config.keySet())) {
            Object value = config.get(key);

            String entryKey = makeKey(prefix, key);
            if (value instanceof Collection) {
                writeCollection(entryKey, (Collection) value, properties);
            } else {
                properties.setProperty(entryKey, asString(value));
            }
        }
    }

    private static  void writeCollection(String prefix, Collection collection, Properties properties) {
        int i = 0;
        for (Object value : collection) {
            String key = makeKey(prefix, Integer.toString(i));
            if (value instanceof Collection) {
                throw new IncompatibleValueException("Properties not allowed to have collection in collection");
            } else {
                properties.setProperty(key, asString(value));
            }
            ++i;
        }
    }

    private static String makeKey(String prefix, String key) {
        if (prefix.length() > 0) {
            return String.format("%s.%s", prefix, key);
        }
        return key;
    }
}