/**
 * 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.hbase;

import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hbase.mapreduce.HFileOutputFormat;
import org.apache.hadoop.hbase.mapreduce.LoadIncrementalHFiles;
import org.apache.hadoop.hbase.mapreduce.PutSortReducer;
import org.apache.hadoop.hbase.mapreduce.hadoopbackport.TotalOrderPartitioner;

import java.io.IOException;
import java.net.URI;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.JobStatus;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static org.apache.hadoop.hbase.mapreduce.hadoopbackport.TotalOrderPartitioner.DEFAULT_PATH;


/**
 * MapReduce job which reads a series of Puts stored in a sequence file
 * and imports the data into HBase. It needs to create the necessary HBase
 * regions using HFileOutputFormat and then notify the correct region servers
 * to doBulkLoad(). This will be used After an MR job has written the SequenceFile
 * and data needs to be bulk loaded onto HBase.
 */
class ImportSequenceFile {
    private final static Logger LOG = LoggerFactory.getLogger(ImportSequenceFile.class);
    private final static String NAME = "HCatImportSequenceFile";
    private final static String IMPORTER_WORK_DIR = "_IMPORTER_MR_WORK_DIR";


    private static class SequenceFileImporter extends Mapper<ImmutableBytesWritable, Put, ImmutableBytesWritable, Put> {

        @Override
        public void map(ImmutableBytesWritable rowKey, Put value,
                        Context context)
            throws IOException {
            try {
                context.write(new ImmutableBytesWritable(value.getRow()), value);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    private static class ImporterOutputFormat extends HFileOutputFormat {
        @Override
        public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException {
            final OutputCommitter baseOutputCommitter = super.getOutputCommitter(context);

            return new OutputCommitter() {
                @Override
                public void setupJob(JobContext jobContext) throws IOException {
                    baseOutputCommitter.setupJob(jobContext);
                }

                @Override
                public void setupTask(TaskAttemptContext taskContext) throws IOException {
                    baseOutputCommitter.setupTask(taskContext);
                }

                @Override
                public boolean needsTaskCommit(TaskAttemptContext taskContext) throws IOException {
                    return baseOutputCommitter.needsTaskCommit(taskContext);
                }

                @Override
                public void commitTask(TaskAttemptContext taskContext) throws IOException {
                    baseOutputCommitter.commitTask(taskContext);
                }

                @Override
                public void abortTask(TaskAttemptContext taskContext) throws IOException {
                    baseOutputCommitter.abortTask(taskContext);
                }

                @Override
                public void abortJob(JobContext jobContext, JobStatus.State state) throws IOException {
                    try {
                        baseOutputCommitter.abortJob(jobContext, state);
                    } finally {
                        cleanupScratch(jobContext);
                    }
                }

                @Override
                public void commitJob(JobContext jobContext) throws IOException {
                    try {
                        baseOutputCommitter.commitJob(jobContext);
                        Configuration conf = jobContext.getConfiguration();
                        try {
                            //import hfiles
                            new LoadIncrementalHFiles(conf)
                                .doBulkLoad(HFileOutputFormat.getOutputPath(jobContext),
                                    new HTable(conf,
                                        conf.get(HBaseConstants.PROPERTY_OUTPUT_TABLE_NAME_KEY)));
                        } catch (Exception e) {
                            throw new IOException("BulkLoad failed.", e);
                        }
                    } finally {
                        cleanupScratch(jobContext);
                    }
                }

                @Override
                public void cleanupJob(JobContext context) throws IOException {
                    try {
                        baseOutputCommitter.cleanupJob(context);
                    } finally {
                        cleanupScratch(context);
                    }
                }

                private void cleanupScratch(JobContext context) throws IOException {
                    FileSystem fs = FileSystem.get(context.getConfiguration());
                    fs.delete(HFileOutputFormat.getOutputPath(context), true);
                }
            };
        }
    }

    private static Job createSubmittableJob(Configuration conf, String tableName, Path inputDir, Path scratchDir, boolean localMode)
        throws IOException {
        Job job = new Job(conf, NAME + "_" + tableName);
        job.setJarByClass(SequenceFileImporter.class);
        FileInputFormat.setInputPaths(job, inputDir);
        job.setInputFormatClass(SequenceFileInputFormat.class);
        job.setMapperClass(SequenceFileImporter.class);

        HTable table = new HTable(conf, tableName);
        job.setReducerClass(PutSortReducer.class);
        FileOutputFormat.setOutputPath(job, scratchDir);
        job.setMapOutputKeyClass(ImmutableBytesWritable.class);
        job.setMapOutputValueClass(Put.class);
        HFileOutputFormat.configureIncrementalLoad(job, table);
        //override OutputFormatClass with our own so we can include cleanup in the committer
        job.setOutputFormatClass(ImporterOutputFormat.class);

        //local mode doesn't support symbolic links so we have to manually set the actual path
        if (localMode) {
            String partitionFile = null;
            for (URI uri : DistributedCache.getCacheFiles(job.getConfiguration())) {
                if (DEFAULT_PATH.equals(uri.getFragment())) {
                    partitionFile = uri.toString();
                    break;
                }
            }
            partitionFile = partitionFile.substring(0, partitionFile.lastIndexOf("#"));
            job.getConfiguration().set(TotalOrderPartitioner.PARTITIONER_PATH, partitionFile.toString());
        }

        return job;
    }

    /**
     * Method to run the Importer MapReduce Job. Normally will be called by another MR job
     * during OutputCommitter.commitJob().
     * @param parentContext JobContext of the parent job
     * @param tableName name of table to bulk load data into
     * @param InputDir path of SequenceFile formatted data to read
     * @param scratchDir temporary path for the Importer MR job to build the HFiles which will be imported
     * @return
     */
    static boolean runJob(JobContext parentContext, String tableName, Path InputDir, Path scratchDir) {
        Configuration parentConf = parentContext.getConfiguration();
        Configuration conf = new Configuration();
        for (Map.Entry<String, String> el : parentConf) {
            if (el.getKey().startsWith("hbase."))
                conf.set(el.getKey(), el.getValue());
            if (el.getKey().startsWith("mapred.cache.archives"))
                conf.set(el.getKey(), el.getValue());
        }

        //Inherit jar dependencies added to distributed cache loaded by parent job
        conf.set("mapred.job.classpath.archives", parentConf.get("mapred.job.classpath.archives", ""));
        conf.set("mapreduce.job.cache.archives.visibilities", parentConf.get("mapreduce.job.cache.archives.visibilities", ""));

        //Temporary fix until hbase security is ready
        //We need the written HFile to be world readable so
        //hbase regionserver user has the privileges to perform a hdfs move
        if (parentConf.getBoolean("hadoop.security.authorization", false)) {
            FsPermission.setUMask(conf, FsPermission.valueOf("----------"));
        }

        conf.set(HBaseConstants.PROPERTY_OUTPUT_TABLE_NAME_KEY, tableName);
        conf.setBoolean(JobContext.JOB_CANCEL_DELEGATION_TOKEN, false);

        boolean localMode = "local".equals(conf.get("mapred.job.tracker"));

        boolean success = false;
        try {
            FileSystem fs = FileSystem.get(parentConf);
            Path workDir = new Path(new Job(parentConf).getWorkingDirectory(), IMPORTER_WORK_DIR);
            if (!fs.mkdirs(workDir))
                throw new IOException("Importer work directory already exists: " + workDir);
            Job job = createSubmittableJob(conf, tableName, InputDir, scratchDir, localMode);
            job.setWorkingDirectory(workDir);
            job.getCredentials().addAll(parentContext.getCredentials());
            success = job.waitForCompletion(true);
            fs.delete(workDir, true);
            //We only cleanup on success because failure might've been caused by existence of target directory
            if (localMode && success) {
                new ImporterOutputFormat().getOutputCommitter(org.apache.hadoop.mapred.HCatMapRedUtil.createTaskAttemptContext(conf, new TaskAttemptID())).commitJob(job);
            }
        } catch (InterruptedException e) {
            LOG.error("ImportSequenceFile Failed", e);
        } catch (ClassNotFoundException e) {
            LOG.error("ImportSequenceFile Failed", e);
        } catch (IOException e) {
            LOG.error("ImportSequenceFile Failed", e);
        }
        return success;
    }

}