name.marcelomorales.siqisiqi.configuration.ConfigProvider.java Source code

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Here is the source code for name.marcelomorales.siqisiqi.configuration.ConfigProvider.java

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/*
 * Copyright 2013 Marcelo Morales me@marcelomorales.name
 *
 *    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 name.marcelomorales.siqisiqi.configuration;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nullable;
import javax.inject.Inject;
import javax.inject.Provider;
import java.io.File;
import java.text.MessageFormat;
import java.util.Map;

/**
 * @author Marcelo Morales
 *         Since: 8/23/13
 */
public class ConfigProvider implements Provider<Config> {

    private static final Logger LOGGER = LoggerFactory.getLogger(ConfigProvider.class);

    private static final Multimap<String, String> TEMPLATES = ImmutableMultimap.<String, String>builder()
            .put("APPDATA", "{0}/{1}/{2}"). // Windows personal ej  \Documents And Settings\TheProject\example.json}
            put("HOME", "{0}/.{1}/{2}"). // Linux personal ej  /home/marcelo/.theproject/example.json
            put("HOME", "{0}/.{2}"). // Linux personal ej  /home/marcelo/.example.json
            put("PROGRAMDATA", "{0}/{1}/{2}"). // Windows global
            put("", "/etc/{1}/{2}"). // Linux global
            put("", "/etc/{2}").build(); // Linux global (2)

    private final String applicationName;

    private final String vendorName;

    @Inject
    public ConfigProvider(String vendorName, String applicationName) {
        this.vendorName = vendorName;
        this.applicationName = applicationName;
    }

    @Override
    public Config get() {

        Config config = ConfigFactory.systemProperties();

        for (String fileTemplate : possibleConfigFilePositions()) {
            config = config.withFallback(ConfigFactory.parseFileAnySyntax(new File(fileTemplate)));
        }

        config = config.withFallback(ConfigFactory.parseResourcesAnySyntax(applicationName));

        config = config.withFallback(ConfigFactory.defaultReference());

        return config;
    }

    public Iterable<String> possibleConfigFilePositions() {

        // Filter out when APPDATA or HOME or anything else is missing
        final Multimap<String, String> applicableTemplates = Multimaps.filterKeys(TEMPLATES,
                new Predicate<String>() {

                    @Override
                    public boolean apply(@Nullable String input) {
                        return Strings.isNullOrEmpty(input) || !Strings.isNullOrEmpty(System.getenv(input));
                    }
                });

        final Iterable<String> transform = Iterables.transform(applicableTemplates.entries(),
                new Function<Map.Entry<String, String>, String>() {

                    @Override
                    public String apply(Map.Entry<String, String> input) {
                        return MessageFormat.format(input.getValue(), System.getenv(input.getKey()), vendorName,
                                applicationName);
                    }
                });

        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("Will check all these paths in order {}", Iterables.toString(transform));
        }

        return transform;
    }

    public ConfigProvider lifted(final String subconfigKey) {
        if (Strings.isNullOrEmpty(subconfigKey)) {
            return this;
        }
        return new ConfigProvider(vendorName, applicationName) {

            @Override
            public Config get() {
                return lift(super.get(), subconfigKey);
            }
        };
    }

    public static Config lift(Config original, String subconfigKey) {
        return original.getConfig(subconfigKey).withFallback(original);
    }
}