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 *   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.cayenne.dba.oracle;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.map.DbAttribute;
import org.apache.cayenne.query.BatchQuery;
import org.apache.cayenne.query.BatchQueryRow;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;

/**
 * Helper class to extract the information from BatchQueries, essential for LOB
 * columns processing.
 * 
 */
class Oracle8LOBBatchQueryWrapper {

	protected BatchQuery query;

	protected List<DbAttribute> dbAttributes;

	// attribute list decoders
	protected boolean[] qualifierAttributes;
	protected boolean[] allLOBAttributes;
	protected Object[] updatedLOBAttributes;

	Oracle8LOBBatchQueryWrapper(BatchQuery query) {
		this.query = query;
		this.dbAttributes = query.getDbAttributes();

		int len = dbAttributes.size();
		this.qualifierAttributes = new boolean[len];
		this.allLOBAttributes = new boolean[len];
		this.updatedLOBAttributes = new Object[len];

		indexQualifierAttributes();
	}

	/**
	 * Indexes attributes
	 */
	protected void indexQualifierAttributes() {
		int len = this.dbAttributes.size();
		for (int i = 0; i < len; i++) {
			DbAttribute attribute = this.dbAttributes.get(i);
			int type = attribute.getType();
			qualifierAttributes[i] = attribute.isPrimaryKey();
			allLOBAttributes[i] = type == Types.BLOB || type == Types.CLOB;
		}
	}

	/**
	 * Indexes attributes
	 */
	void indexLOBAttributes(BatchQueryRow row) {
		int len = updatedLOBAttributes.length;
		for (int i = 0; i < len; i++) {
			updatedLOBAttributes[i] = null;

			if (allLOBAttributes[i]) {
				// skip null and empty LOBs
				Object value = row.getValue(i);

				if (value == null) {
					continue;
				}

				if (dbAttributes.get(i).getType() == Types.BLOB) {
					updatedLOBAttributes[i] = convertToBlobValue(value);
				} else {
					updatedLOBAttributes[i] = convertToClobValue(value);
				}
			}
		}
	}

	/**
	 * Converts value to byte[] if possible.
	 */
	protected byte[] convertToBlobValue(Object value) {
		if (value instanceof byte[]) {
			byte[] bytes = (byte[]) value;
			return bytes.length == 0 ? null : bytes;
		} else if (value instanceof Serializable) {
			ByteArrayOutputStream bytes = new ByteArrayOutputStream() {

				@Override
				public synchronized byte[] toByteArray() {
					return buf;
				}
			};

			try (ObjectOutputStream out = new ObjectOutputStream(bytes)) {
				out.writeObject(value);
			} catch (IOException e) {
				throw new CayenneRuntimeException("Error serializing object", e);
			}

			return bytes.toByteArray();
		}

		return null;
	}

	/**
	 * Converts to char[] or String. Both are acceptable when writing CLOBs.
	 */
	protected Object convertToClobValue(Object value) {

		if (value instanceof char[]) {
			char[] chars = (char[]) value;
			return chars.length == 0 ? null : chars;
		} else {
			String strValue = value.toString();
			return strValue.length() == 0 ? null : strValue;
		}
	}

	/**
	 * Returns a list of DbAttributes used in the qualifier of the query that
	 * selects a LOB row for LOB update.
	 */
	List<DbAttribute> getDbAttributesForLOBSelectQualifier() {

		int len = qualifierAttributes.length;
		List<DbAttribute> attributes = new ArrayList<>(len);

		for (int i = 0; i < len; i++) {
			if (this.qualifierAttributes[i]) {
				attributes.add(this.dbAttributes.get(i));
			}
		}
		return attributes;
	}

	/**
	 * Returns a list of DbAttributes that correspond to the LOB columns updated
	 * in the current row in the batch query. The list will not include LOB
	 * attributes that are null or empty.
	 */
	List<DbAttribute> getDbAttributesForUpdatedLOBColumns() {

		int len = updatedLOBAttributes.length;
		List<DbAttribute> attributes = new ArrayList<>(len);

		for (int i = 0; i < len; i++) {
			if (this.updatedLOBAttributes[i] != null) {
				attributes.add(this.dbAttributes.get(i));
			}
		}
		return attributes;
	}

	List<Object> getValuesForLOBSelectQualifier(BatchQueryRow row) {

		int len = this.qualifierAttributes.length;
		List<Object> values = new ArrayList<>(len);
		for (int i = 0; i < len; i++) {
			if (this.qualifierAttributes[i]) {
				values.add(row.getValue(i));
			}
		}

		return values;
	}

	List<Object> getValuesForUpdatedLOBColumns() {

		int len = this.updatedLOBAttributes.length;
		List<Object> values = new ArrayList<>(len);
		for (Object updatedLOBAttribute : this.updatedLOBAttributes) {
			if (updatedLOBAttribute != null) {
				values.add(updatedLOBAttribute);
			}
		}

		return values;
	}

}