com.flowpowered.cerealization.config.migration.ConfigurationMigrator.java Source code

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Here is the source code for com.flowpowered.cerealization.config.migration.ConfigurationMigrator.java

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/*
 * This file is part of Flow Cerealization, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2013 Spout LLC <https://spout.org/>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.flowpowered.cerealization.config.migration;

import java.io.File;
import java.io.IOException;
import java.util.Map;

import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.Validate;

import com.flowpowered.cerealization.config.Configuration;
import com.flowpowered.cerealization.config.ConfigurationException;
import com.flowpowered.cerealization.config.ConfigurationNode;
import com.flowpowered.cerealization.config.FileConfiguration;

/**
 * A simple migrator for configurations that moves values from one key to another. It can also convert values
 */
public abstract class ConfigurationMigrator {
    private final Configuration configuration;

    protected ConfigurationMigrator(Configuration configuration) {
        Validate.notNull(configuration);
        this.configuration = configuration;
    }

    /**
     * Put together a collection of all keys to be migrated and their associated actions. This can be put in a static HashMap, or generated on each invocation
     *
     * @return The map of configuration keys to their associated actions
     */
    protected abstract Map<String[], MigrationAction> getMigrationActions();

    public Configuration getConfiguration() {
        return configuration;
    }

    /**
     * This method checks whether migration is needed on the {@link Configuration} this instance is constructed with
     *
     * @return Whether migration is needed
     */
    protected abstract boolean shouldMigrate();

    /**
     * Perform migration of the configuration this object was constructed with If migration was not necessary ({@link #shouldMigrate()} returned false), the method invocation will be considered
     * successful. If {@link #configuration} is a {@link com.flowpowered.cerealization.config.FileConfiguration}, the file the configuration vas previously stored in will be moved to (file name).old as a backup of
     * the data before migration
     *
     * @throws MigrationException if the configuration could not be successfully migrated
     */
    public void migrate() throws MigrationException {
        if (!shouldMigrate()) {
            return;
        }

        if (configuration instanceof FileConfiguration) {
            File oldFile = ((FileConfiguration) configuration).getFile();
            try {
                FileUtils.moveFile(oldFile, new File(oldFile.getAbsolutePath() + ".old"));
            } catch (IOException e) {
                throw new MigrationException(e);
            }
        }

        for (Map.Entry<String[], MigrationAction> entry : getMigrationActions().entrySet()) {
            final ConfigurationNode existingNode = configuration.getNode(entry.getKey());
            final Object existing = existingNode.getValue();
            existingNode.remove();
            if (existing == null || entry.getValue() == null) {
                continue;
            }
            final String[] newKey = entry.getValue().convertKey(entry.getKey());
            final Object newValue = entry.getValue().convertValue(existing);
            configuration.getNode(newKey).setValue(newValue);
        }
        try {
            configuration.save();
        } catch (ConfigurationException e) {
            throw new MigrationException(e);
        }
    }
}