/* This file is part of VoltDB.
 * Copyright (C) 2008-2017 VoltDB Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with VoltDB.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.voltdb.sysprocs;

import org.voltdb.DependencyPair;
import org.voltdb.DependencyPair.TableDependencyPair;
import org.voltdb.ParameterSet;
import org.voltdb.ProcInfo;
import org.voltdb.SystemProcedureExecutionContext;
import org.voltdb.VoltDB;
import org.voltdb.VoltTable;
import org.voltdb.common.Constants;
import org.voltdb.dtxn.DtxnConstants;
import org.voltdb.utils.VoltTableUtil;

import java.util.List;
import java.util.Map;

/**
 * Execute a SwapTables as an multi-partition SQL statement.
 * This code coordinates the execution of the plan fragments generated by the
 * embedded planner process.
 *
 * AdHocBase implements the core logic.
 * This subclass is needed for @ProcInfo.
 */
@ProcInfo(singlePartition = false)
public class SwapTables extends AdHocBase {

    private static final int DEP_swapTables = (int) SysProcFragmentId.PF_swapTables | DtxnConstants.MULTIPARTITION_DEPENDENCY;
    private static final int DEP_swapTablesAggregate = (int) SysProcFragmentId.PF_swapTablesAggregate;

    @Override
    public long[] getPlanFragmentIds() {
        return new long[] { SysProcFragmentId.PF_swapTables, SysProcFragmentId.PF_swapTablesAggregate };
    }

    @Override
    public DependencyPair executePlanFragment(Map<Integer, List<VoltTable>> dependencies, long fragmentId, ParameterSet params, SystemProcedureExecutionContext context) {
        VoltTable dummy = new VoltTable(STATUS_SCHEMA);
        dummy.addRow(STATUS_OK);

        if (fragmentId == SysProcFragmentId.PF_swapTables) {
            // issue the callback once on each node
            if (context.isLowestSiteId()) {
                VoltDB.instance().swapTables((String) params.getParam(0), (String) params.getParam(1));
            }
            return new TableDependencyPair(DEP_swapTables, dummy);
        }
        else if (fragmentId == SysProcFragmentId.PF_swapTablesAggregate) {
            return new TableDependencyPair(DEP_swapTablesAggregate,
                    VoltTableUtil.unionTables(dependencies.get(DEP_swapTables)));
        }

        assert false;
        return null;
    }

    /**
     * System procedure run hook.
     * Use the base class implementation.
     *
     * @param ctx execution context
     * @param serializedBatchData serialized batch data
     *
     * @return  results as VoltTable array
     */
    public VoltTable[] run(SystemProcedureExecutionContext ctx, byte[] serializedBatchData) {
        VoltTable[] result = runAdHoc(ctx, serializedBatchData);

        String stmt = new String(
                decodeSerializedBatchData(serializedBatchData).getSecond()[0].sql,
                Constants.UTF8ENCODING);
        // stmt is of the format "@SwapTables <table1> <table2>"
        String[] stmtParams = stmt.split(" ");
        performSwapTablesCallback(stmtParams[1], stmtParams[2]);

        return result;
    }

    private VoltTable[] performSwapTablesCallback(String oneTable, String otherTable)
    {
        SynthesizedPlanFragment pfs[] = new SynthesizedPlanFragment[2];

        pfs[0] = new SynthesizedPlanFragment();
        pfs[0].fragmentId = SysProcFragmentId.PF_swapTables;
        pfs[0].outputDepId = DEP_swapTables;
        pfs[0].inputDepIds = new int[]{};
        pfs[0].multipartition = true;
        pfs[0].parameters = ParameterSet.fromArrayNoCopy(oneTable, otherTable);

        pfs[1] = new SynthesizedPlanFragment();
        pfs[1].fragmentId = SysProcFragmentId.PF_swapTablesAggregate;
        pfs[1].outputDepId = DEP_swapTablesAggregate;
        pfs[1].inputDepIds = new int[]{DEP_swapTables};
        pfs[1].multipartition = false;
        pfs[1].parameters = ParameterSet.emptyParameterSet();

        return executeSysProcPlanFragments(pfs, DEP_swapTablesAggregate);
    }
}