/**
 * 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 org.apache.hcatalog;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MiniMRCluster;

/**
 * This class builds a single instance of itself with the Singleton
 * design pattern. While building the single instance, it sets up a
 * mini cluster that actually consists of a mini DFS cluster and a
 * mini MapReduce cluster on the local machine and also sets up the
 * environment for Pig to run on top of the mini cluster.
 */
public class MiniCluster {
    private MiniDFSCluster m_dfs = null;
    private MiniMRCluster m_mr = null;
    private FileSystem m_fileSys = null;
    private JobConf m_conf = null;

    private final static MiniCluster INSTANCE = new MiniCluster();
    private static boolean isSetup = true;

    private MiniCluster() {
        setupMiniDfsAndMrClusters();
    }

    private void setupMiniDfsAndMrClusters() {
        try {
            final int dataNodes = 1;     // There will be 4 data nodes
            final int taskTrackers = 1;  // There will be 4 task tracker nodes
            Configuration config = new Configuration();

            // Builds and starts the mini dfs and mapreduce clusters
            System.setProperty("hadoop.log.dir", ".");
            m_dfs = new MiniDFSCluster(config, dataNodes, true, null);

            m_fileSys = m_dfs.getFileSystem();
            m_mr = new MiniMRCluster(taskTrackers, m_fileSys.getUri().toString(), 1);

            // Create the configuration hadoop-site.xml file
            File conf_dir = new File(System.getProperty("user.home"), "pigtest/conf/");
            conf_dir.mkdirs();
            File conf_file = new File(conf_dir, "hadoop-site.xml");

            // Write the necessary config info to hadoop-site.xml
            m_conf = m_mr.createJobConf();
            m_conf.setInt("mapred.submit.replication", 1);
            m_conf.set("dfs.datanode.address", "0.0.0.0:0");
            m_conf.set("dfs.datanode.http.address", "0.0.0.0:0");
            m_conf.writeXml(new FileOutputStream(conf_file));

            // Set the system properties needed by Pig
            System.setProperty("cluster", m_conf.get("mapred.job.tracker"));
            System.setProperty("namenode", m_conf.get("fs.default.name"));
            System.setProperty("junit.hadoop.conf", conf_dir.getPath());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Returns the single instance of class MiniClusterBuilder that
     * represents the resouces for a mini dfs cluster and a mini
     * mapreduce cluster.
     */
    public static MiniCluster buildCluster() {
        if (!isSetup) {
            INSTANCE.setupMiniDfsAndMrClusters();
            isSetup = true;
        }
        return INSTANCE;
    }

    public void shutDown() {
        INSTANCE.shutdownMiniDfsAndMrClusters();
    }

    @Override
    protected void finalize() {
        shutdownMiniDfsAndMrClusters();
    }

    private void shutdownMiniDfsAndMrClusters() {
        isSetup = false;
        try {
            if (m_fileSys != null) {
                m_fileSys.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (m_dfs != null) {
            m_dfs.shutdown();
        }
        if (m_mr != null) {
            m_mr.shutdown();
        }
        m_fileSys = null;
        m_dfs = null;
        m_mr = null;
    }

    public Properties getProperties() {
        errorIfNotSetup();
        Properties properties = new Properties();
        assert m_conf != null;
        Iterator<Map.Entry<String, String>> iter = m_conf.iterator();
        while (iter.hasNext()) {
            Map.Entry<String, String> entry = iter.next();
            properties.put(entry.getKey(), entry.getValue());
        }
        return properties;
    }

    public void setProperty(String name, String value) {
        errorIfNotSetup();
        m_conf.set(name, value);
    }

    public FileSystem getFileSystem() {
        errorIfNotSetup();
        return m_fileSys;
    }

    /**
     * Throw RunTimeException if isSetup is false
     */
    private void errorIfNotSetup() {
        if (isSetup) {
            return;
        }
        String msg = "function called on MiniCluster that has been shutdown";
        throw new RuntimeException(msg);
    }

    static public void createInputFile(MiniCluster miniCluster, String fileName,
                                       String[] inputData)
        throws IOException {
        FileSystem fs = miniCluster.getFileSystem();
        createInputFile(fs, fileName, inputData);
    }

    static public void createInputFile(FileSystem fs, String fileName,
                                       String[] inputData) throws IOException {
        Path path = new Path(fileName);
        if (fs.exists(path)) {
            throw new IOException("File " + fileName + " already exists on the minicluster");
        }
        FSDataOutputStream stream = fs.create(path);
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(stream, "UTF-8"));
        for (int i = 0; i < inputData.length; i++) {
            pw.println(inputData[i]);
        }
        pw.close();

    }

    /**
     * Helper to remove a dfs file from the minicluster DFS
     *
     * @param miniCluster reference to the Minicluster where the file should be deleted
     * @param fileName pathname of the file to be deleted
     * @throws IOException
     */
    static public void deleteFile(MiniCluster miniCluster, String fileName)
        throws IOException {
        FileSystem fs = miniCluster.getFileSystem();
        fs.delete(new Path(fileName), true);
    }
}