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/**
 * 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.presidentio.but.unit.common;

import com.presidentio.but.unit.common.exception.DestroyUnitException;
import com.presidentio.but.unit.common.exception.InitUnitException;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.io.IOException;
import java.nio.file.*;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Map;

/**
 * Created by presidentio on 9/18/15.
 */
public abstract class BaseUnit implements Unit {

    private static final Logger LOGGER = LogManager.getLogger(BaseUnit.class);

    private static final Path GLOBAL_TMP_DIR;

    static {
        try {
            GLOBAL_TMP_DIR = Files.createDirectories(Paths.get(System.getProperty("java.io.tmpdir"), "but"));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private String unitName;

    private Path tmpDir;

    public BaseUnit(String unitName) {
        this.unitName = unitName;
        try {
            tmpDir = Files.createTempDirectory(GLOBAL_TMP_DIR, unitName);
        } catch (IOException e) {
            throw new RuntimeException("Failed to create tmp dir inside: " + GLOBAL_TMP_DIR, e);
        }
    }

    protected Path getTmpDir() {
        return tmpDir;
    }

    @Override
    public void start() throws InitUnitException {
        LOGGER.info(String.format("Starting %s unit", unitName));
        init();
        LOGGER.info(String.format("Unit %s started", unitName));
    }

    @Override
    public void stop() throws DestroyUnitException {
        LOGGER.info(String.format("Destroying %s unit", unitName));
        destroy();
        try {
            Files.walkFileTree(tmpDir, new SimpleFileVisitor() {
                @Override
                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                    Files.delete(file);
                    return super.visitFile(file, attrs);
                }

                @Override
                public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                    Files.delete(dir);
                    return super.postVisitDirectory(dir, exc);
                }
            });
        } catch (IOException e) {
            throw new DestroyUnitException("Failed to delete tmp dir: " + tmpDir, e);
        }
        LOGGER.info(String.format("Unit %s destroyed", unitName));
    }

    public String getUnitName() {
        return unitName;
    }

    protected abstract void destroy() throws DestroyUnitException;

    protected abstract void init() throws InitUnitException;

    protected String replacePlaceholders(String script, Map configurations) {
        for (Map.Entry configuration : configurations.entrySet()) {
            script = script.replaceAll("\\$\\{" + configuration.getKey() + "\\}", configuration.getValue());
        }
        return script;
    }
}