/**
 * 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 java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.hbase.HBaseSerDe;
import org.apache.hcatalog.common.HCatConstants;
import org.apache.hcatalog.common.HCatUtil;
import org.apache.hcatalog.data.schema.HCatFieldSchema;
import org.apache.hcatalog.data.schema.HCatSchema;
import org.apache.hcatalog.hbase.snapshot.RevisionManager;
import org.apache.hcatalog.hbase.snapshot.RevisionManagerFactory;
import org.apache.hcatalog.hbase.snapshot.TableSnapshot;
import org.apache.hcatalog.hbase.snapshot.Transaction;
import org.apache.hcatalog.mapreduce.HCatTableInfo;
import org.apache.hcatalog.mapreduce.InputJobInfo;
import org.apache.hcatalog.mapreduce.OutputJobInfo;
import org.apache.hcatalog.mapreduce.StorerInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * The Class HBaseRevisionManagerUtil has utility methods to interact with Revision Manager
 *
 */
class HBaseRevisionManagerUtil {

    private final static Logger LOG = LoggerFactory.getLogger(HBaseRevisionManagerUtil.class);

    private HBaseRevisionManagerUtil() {
    }

    /**
     * Creates the latest snapshot of the table.
     *
     * @param jobConf The job configuration.
     * @param hbaseTableName The fully qualified name of the HBase table.
     * @param tableInfo HCat table information
     * @return An instance of HCatTableSnapshot
     * @throws IOException Signals that an I/O exception has occurred.
     */
    static HCatTableSnapshot createSnapshot(Configuration jobConf,
                                            String hbaseTableName, HCatTableInfo tableInfo) throws IOException {

        RevisionManager rm = null;
        TableSnapshot snpt;
        try {
            rm = getOpenedRevisionManager(jobConf);
            snpt = rm.createSnapshot(hbaseTableName);
        } finally {
            closeRevisionManagerQuietly(rm);
        }

        HCatTableSnapshot hcatSnapshot = HBaseRevisionManagerUtil.convertSnapshot(snpt, tableInfo);
        return hcatSnapshot;
    }

    /**
     * Creates the snapshot using the revision specified by the user.
     *
     * @param jobConf The job configuration.
     * @param tableName The fully qualified name of the table whose snapshot is being taken.
     * @param revision The revision number to use for the snapshot.
     * @return An instance of HCatTableSnapshot.
     * @throws IOException Signals that an I/O exception has occurred.
     */
    static HCatTableSnapshot createSnapshot(Configuration jobConf,
                                            String tableName, long revision)
        throws IOException {

        TableSnapshot snpt;
        RevisionManager rm = null;
        try {
            rm = getOpenedRevisionManager(jobConf);
            snpt = rm.createSnapshot(tableName, revision);
        } finally {
            closeRevisionManagerQuietly(rm);
        }

        String inputJobString = jobConf.get(HCatConstants.HCAT_KEY_JOB_INFO);
        if (inputJobString == null) {
            throw new IOException(
                "InputJobInfo information not found in JobContext. "
                    + "HCatInputFormat.setInput() not called?");
        }
        InputJobInfo inputInfo = (InputJobInfo) HCatUtil.deserialize(inputJobString);
        HCatTableSnapshot hcatSnapshot = HBaseRevisionManagerUtil
            .convertSnapshot(snpt, inputInfo.getTableInfo());

        return hcatSnapshot;
    }

    /**
     * Gets an instance of revision manager which is opened.
     *
     * @param jobConf The job configuration.
     * @return RevisionManager An instance of revision manager.
     * @throws IOException
     */
    static RevisionManager getOpenedRevisionManager(Configuration jobConf) throws IOException {
        return RevisionManagerFactory.getOpenedRevisionManager(jobConf);
    }

    static void closeRevisionManagerQuietly(RevisionManager rm) {
        if (rm != null) {
            try {
                rm.close();
            } catch (IOException e) {
                LOG.warn("Error while trying to close revision manager", e);
            }
        }
    }


    static HCatTableSnapshot convertSnapshot(TableSnapshot hbaseSnapshot,
                                             HCatTableInfo hcatTableInfo) throws IOException {

        HCatSchema hcatTableSchema = hcatTableInfo.getDataColumns();
        Map<String, String> hcatHbaseColMap = getHCatHBaseColumnMapping(hcatTableInfo);
        HashMap<String, Long> revisionMap = new HashMap<String, Long>();

        for (HCatFieldSchema fSchema : hcatTableSchema.getFields()) {
            if (hcatHbaseColMap.containsKey(fSchema.getName())) {
                String colFamily = hcatHbaseColMap.get(fSchema.getName());
                long revisionID = hbaseSnapshot.getRevision(colFamily);
                revisionMap.put(fSchema.getName(), revisionID);
            }
        }

        HCatTableSnapshot hcatSnapshot = new HCatTableSnapshot(
            hcatTableInfo.getDatabaseName(), hcatTableInfo.getTableName(), revisionMap, hbaseSnapshot.getLatestRevision());
        return hcatSnapshot;
    }

    static TableSnapshot convertSnapshot(HCatTableSnapshot hcatSnapshot,
                                         HCatTableInfo hcatTableInfo) throws IOException {

        HCatSchema hcatTableSchema = hcatTableInfo.getDataColumns();
        Map<String, Long> revisionMap = new HashMap<String, Long>();
        Map<String, String> hcatHbaseColMap = getHCatHBaseColumnMapping(hcatTableInfo);
        for (HCatFieldSchema fSchema : hcatTableSchema.getFields()) {
            String colFamily = hcatHbaseColMap.get(fSchema.getName());
            if (hcatSnapshot.containsColumn(fSchema.getName())) {
                long revision = hcatSnapshot.getRevision(fSchema.getName());
                revisionMap.put(colFamily, revision);
            }
        }

        String fullyQualifiedName = hcatSnapshot.getDatabaseName() + "."
            + hcatSnapshot.getTableName();
        return new TableSnapshot(fullyQualifiedName, revisionMap, hcatSnapshot.getLatestRevision());

    }

    /**
     * Begins a transaction in the revision manager for the given table.
     * @param qualifiedTableName Name of the table
     * @param tableInfo HCat Table information
     * @param jobConf Job Configuration
     * @return The new transaction in revision manager
     * @throws IOException
     */
    static Transaction beginWriteTransaction(String qualifiedTableName,
                                             HCatTableInfo tableInfo, Configuration jobConf) throws IOException {
        Transaction txn;
        RevisionManager rm = null;
        try {
            rm = HBaseRevisionManagerUtil.getOpenedRevisionManager(jobConf);
            String hBaseColumns = tableInfo.getStorerInfo().getProperties()
                .getProperty(HBaseSerDe.HBASE_COLUMNS_MAPPING);
            String[] splits = hBaseColumns.split("[,:]");
            Set<String> families = new HashSet<String>();
            for (int i = 0; i < splits.length; i += 2) {
                if (!splits[i].isEmpty())
                    families.add(splits[i]);
            }
            txn = rm.beginWriteTransaction(qualifiedTableName, new ArrayList<String>(families));
        } finally {
            HBaseRevisionManagerUtil.closeRevisionManagerQuietly(rm);
        }
        return txn;
    }

    static Transaction getWriteTransaction(Configuration conf) throws IOException {
        OutputJobInfo outputJobInfo = (OutputJobInfo) HCatUtil.deserialize(conf.get(HCatConstants.HCAT_KEY_OUTPUT_INFO));
        return (Transaction) HCatUtil.deserialize(outputJobInfo.getProperties()
            .getProperty(HBaseConstants.PROPERTY_WRITE_TXN_KEY));
    }

    static void setWriteTransaction(Configuration conf, Transaction txn) throws IOException {
        OutputJobInfo outputJobInfo = (OutputJobInfo) HCatUtil.deserialize(conf.get(HCatConstants.HCAT_KEY_OUTPUT_INFO));
        outputJobInfo.getProperties().setProperty(HBaseConstants.PROPERTY_WRITE_TXN_KEY, HCatUtil.serialize(txn));
        conf.set(HCatConstants.HCAT_KEY_OUTPUT_INFO, HCatUtil.serialize(outputJobInfo));
    }

    /**
     * Get the Revision number that will be assigned to this job's output data
     * @param conf configuration of the job
     * @return the revision number used
     * @throws IOException
     */
    static long getOutputRevision(Configuration conf) throws IOException {
        return getWriteTransaction(conf).getRevisionNumber();
    }

    private static Map<String, String> getHCatHBaseColumnMapping(HCatTableInfo hcatTableInfo)
        throws IOException {

        HCatSchema hcatTableSchema = hcatTableInfo.getDataColumns();
        StorerInfo storeInfo = hcatTableInfo.getStorerInfo();
        String hbaseColumnMapping = storeInfo.getProperties().getProperty(
            HBaseSerDe.HBASE_COLUMNS_MAPPING);

        Map<String, String> hcatHbaseColMap = new HashMap<String, String>();
        List<String> columnFamilies = new ArrayList<String>();
        List<String> columnQualifiers = new ArrayList<String>();
        HBaseUtil.parseColumnMapping(hbaseColumnMapping, columnFamilies,
            null, columnQualifiers, null);

        for (HCatFieldSchema column : hcatTableSchema.getFields()) {
            int fieldPos = hcatTableSchema.getPosition(column.getName());
            String colFamily = columnFamilies.get(fieldPos);
            if (colFamily.equals(HBaseSerDe.HBASE_KEY_COL) == false) {
                hcatHbaseColMap.put(column.getName(), colFamily);
            }
        }

        return hcatHbaseColMap;
    }

}