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 *  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
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 *  Unless required by applicable law or agreed to in writing,
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 *  KIND, either express or implied.  See the License for the
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package org.apache.cayenne.dba.sqlserver;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;

import org.apache.cayenne.access.DataNode;
import org.apache.cayenne.access.OperationObserver;
import org.apache.cayenne.access.jdbc.BatchAction;
import org.apache.cayenne.map.DbAttribute;
import org.apache.cayenne.query.BatchQuery;
import org.apache.cayenne.query.InsertBatchQuery;

/**
 * @since 1.2
 */
public class SQLServerBatchAction extends BatchAction {

	public SQLServerBatchAction(BatchQuery batchQuery, DataNode dataNode, boolean runningAsBatch) {
		super(batchQuery, dataNode, runningAsBatch);
	}

	@Override
	public void performAction(Connection connection, OperationObserver observer) throws SQLException, Exception {

		// this condition checks if identity columns are present in the query
		// and adapter
		// is not ready to process them... e.g. if we are using a MS driver...
		boolean identityOverride = expectsToOverrideIdentityColumns();
		if (identityOverride) {
			setIdentityInsert(connection, true);
		}

		try {
			super.performAction(connection, observer);
		} finally {

			// important: turn off IDENTITY_INSERT as SQL Server won't be able
			// to process
			// other identity columns in the same transaction

			// TODO: if an error happens here this would mask the parent error
			if (identityOverride) {
				setIdentityInsert(connection, false);
			}
		}
	}

	protected void setIdentityInsert(Connection connection, boolean on) throws SQLException {

		String flag = on ? " ON" : " OFF";
		String configSQL = "SET IDENTITY_INSERT " + query.getDbEntity().getFullyQualifiedName() + flag;

		dataNode.getJdbcEventLogger().log(configSQL);

		try (Statement statement = connection.createStatement()) {
			statement.execute(configSQL);
		}
	}

	/**
	 * Returns whether a table has identity columns.
	 */
	protected boolean expectsToOverrideIdentityColumns() {
		// jTDS driver supports identity columns, no need for tricks...
		if (dataNode.getAdapter().supportsGeneratedKeys()) {
			return false;
		}

		if (!(query instanceof InsertBatchQuery) || query.getDbEntity() == null) {
			return false;
		}

		// find identity attributes
		for (DbAttribute attribute : query.getDbEntity().getAttributes()) {
			if (attribute.isGenerated()) {
				return true;
			}
		}

		return false;
	}
}