/*
 * 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.phoenix.compile;

import java.sql.SQLException;
import java.util.Collections;

import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.coprocessor.BaseScannerRegionObserver;
import org.apache.phoenix.coprocessor.MetaDataProtocol;
import org.apache.phoenix.execute.MutationState;
import org.apache.phoenix.hbase.index.covered.update.ColumnReference;
import org.apache.phoenix.index.IndexMaintainer;
import org.apache.phoenix.index.PhoenixIndexCodec;
import org.apache.phoenix.jdbc.PhoenixConnection;
import org.apache.phoenix.jdbc.PhoenixStatement;
import org.apache.phoenix.schema.*;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PLong;
import org.apache.phoenix.util.ByteUtil;
import org.apache.phoenix.util.IndexUtil;
import org.apache.phoenix.util.ScanUtil;

import static org.apache.phoenix.schema.types.PDataType.TRUE_BYTES;
import static org.apache.phoenix.util.IndexUtil.addEmptyColumnToScan;


/**
 * Class that compiles plan to generate initial data values after a DDL command for
 * index table.
 */
public class ServerBuildIndexCompiler {
    private final PhoenixConnection connection;
    private final String tableName;
    private PTable dataTable;
    private QueryPlan plan;

    private class RowCountMutationPlan extends BaseMutationPlan {
        private RowCountMutationPlan(StatementContext context, PhoenixStatement.Operation operation) {
            super(context, operation);
        }
        @Override
        public MutationState execute() throws SQLException {
            connection.getMutationState().commitDDLFence(dataTable);
            Tuple tuple = plan.iterator().next();
            long rowCount = 0;
            if (tuple != null) {
                Cell kv = tuple.getValue(0);
                ImmutableBytesWritable tmpPtr = new ImmutableBytesWritable(kv.getValueArray(), kv.getValueOffset(), kv.getValueLength());
                // A single Cell will be returned with the count(*) - we decode that here
                rowCount = PLong.INSTANCE.getCodec().decodeLong(tmpPtr, SortOrder.getDefault());
            }
            // The contract is to return a MutationState that contains the number of rows modified. In this
            // case, it's the number of rows in the data table which corresponds to the number of index
            // rows that were added.
            return new MutationState(0, 0, connection, rowCount);
        }

        @Override
        public QueryPlan getQueryPlan() {
            return plan;
        }
    };
    
    public ServerBuildIndexCompiler(PhoenixConnection connection, String tableName) {
        this.connection = connection;
        this.tableName = tableName;
    }

    public MutationPlan compile(PTable index) throws SQLException {
        try (final PhoenixStatement statement = new PhoenixStatement(connection)) {
            String query = "SELECT count(*) FROM " + tableName;
            this.plan = statement.compileQuery(query);
            TableRef tableRef = plan.getTableRef();
            Scan scan = plan.getContext().getScan();
            ImmutableBytesWritable ptr = new ImmutableBytesWritable();
            dataTable = tableRef.getTable();
            if (index.getIndexType() == PTable.IndexType.GLOBAL &&  dataTable.isTransactional()) {
                throw new IllegalArgumentException(
                        "ServerBuildIndexCompiler does not support global indexes on transactional tables");
            }
            // By default, we'd use a FirstKeyOnly filter as nothing else needs to be projected for count(*).
            // However, in this case, we need to project all of the data columns that contribute to the index.
            IndexMaintainer indexMaintainer = index.getIndexMaintainer(dataTable, connection);
            for (ColumnReference columnRef : indexMaintainer.getAllColumns()) {
                if (index.getImmutableStorageScheme() == PTable.ImmutableStorageScheme.SINGLE_CELL_ARRAY_WITH_OFFSETS) {
                    scan.addFamily(columnRef.getFamily());
                } else {
                    scan.addColumn(columnRef.getFamily(), columnRef.getQualifier());
                }
            }
            IndexMaintainer.serialize(dataTable, ptr, Collections.singletonList(index), plan.getContext().getConnection());
            // Set the scan attributes that UngroupedAggregateRegionObserver will switch on.
            // For local indexes, the BaseScannerRegionObserver.LOCAL_INDEX_BUILD_PROTO attribute, and
            // for global indexes PhoenixIndexCodec.INDEX_PROTO_MD attribute is set to the serialized form of index
            // metadata to build index rows from data table rows. For global indexes, we also need to set (1) the
            // BaseScannerRegionObserver.REBUILD_INDEXES attribute in order to signal UngroupedAggregateRegionObserver
            // that this scan is for building global indexes and (2) the MetaDataProtocol.PHOENIX_VERSION attribute
            // that will be passed as a mutation attribute for the scanned mutations that will be applied on
            // the index table possibly remotely
            if (index.getIndexType() == PTable.IndexType.LOCAL) {
                scan.setAttribute(BaseScannerRegionObserver.LOCAL_INDEX_BUILD_PROTO, ByteUtil.copyKeyBytesIfNecessary(ptr));
            } else {
                scan.setAttribute(PhoenixIndexCodec.INDEX_PROTO_MD, ByteUtil.copyKeyBytesIfNecessary(ptr));
                scan.setAttribute(BaseScannerRegionObserver.REBUILD_INDEXES, TRUE_BYTES);
                ScanUtil.setClientVersion(scan, MetaDataProtocol.PHOENIX_VERSION);
                addEmptyColumnToScan(scan, indexMaintainer.getDataEmptyKeyValueCF(), indexMaintainer.getEmptyKeyValueQualifier());
            }
            if (dataTable.isTransactional()) {
                scan.setAttribute(BaseScannerRegionObserver.TX_STATE, connection.getMutationState().encodeTransaction());
            }

            // Go through MutationPlan abstraction so that we can create local indexes
            // with a connectionless connection (which makes testing easier).
            return new RowCountMutationPlan(plan.getContext(), PhoenixStatement.Operation.UPSERT);
        }
    }
}