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/*
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.server.database;

import javax.servlet.http.HttpServletRequest;

import org.neo4j.cypher.internal.javacompat.ExecutionEngine;
import org.neo4j.kernel.GraphDatabaseQueryService;
import org.neo4j.kernel.api.security.AccessMode;
import org.neo4j.kernel.api.KernelTransaction;
import org.neo4j.kernel.impl.core.ThreadToStatementContextBridge;
import org.neo4j.kernel.impl.coreapi.InternalTransaction;
import org.neo4j.kernel.impl.coreapi.PropertyContainerLocker;
import org.neo4j.kernel.impl.query.Neo4jTransactionalContext;
import org.neo4j.kernel.impl.query.QueryExecutionEngine;
import org.neo4j.kernel.impl.query.QuerySession;
import org.neo4j.kernel.impl.query.TransactionalContext;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
import org.neo4j.server.rest.web.ServerQuerySession;

public class CypherExecutor extends LifecycleAdapter
{
    private final Database database;
    private ExecutionEngine executionEngine;
    private GraphDatabaseQueryService service;
    private ThreadToStatementContextBridge txBridge;

    private static final PropertyContainerLocker locker = new PropertyContainerLocker();

    public CypherExecutor( Database database )
    {
        this.database = database;
    }

    public ExecutionEngine getExecutionEngine()
    {
        return executionEngine;
    }

    @Override
    public void start() throws Throwable
    {
        this.executionEngine = (ExecutionEngine) database.getGraph().getDependencyResolver()
                .resolveDependency( QueryExecutionEngine.class );
        this.service = executionEngine.queryService();
        this.txBridge = service.getDependencyResolver().resolveDependency( ThreadToStatementContextBridge.class );
    }

    @Override
    public void stop() throws Throwable
    {
        this.executionEngine = null;
        this.service = null;
        this.txBridge = null;
    }

    public QuerySession createSession( HttpServletRequest request )
    {
        InternalTransaction transaction = service.beginTransaction( KernelTransaction.Type.implicit, AccessMode.Static.FULL );
        TransactionalContext context = new Neo4jTransactionalContext( service, transaction, txBridge.get(), locker );
        return new ServerQuerySession( request, context );
    }
}