LabelBuilder.java

/*
 * Copyright 2016 Christoph Böhme
 *
 * Licensed 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.culturegraph.mf.biblio.iso2709;

import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.BASE_ADDRESS_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.BASE_ADDRESS_START;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.FIELD_LENGTH_LENGTH_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.FIELD_START_LENGTH_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.IDENTIFIER_LENGTH_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.IMPL_CODES_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.IMPL_CODES_START;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.IMPL_DEFINED_PART_LENGTH_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.INDICATOR_LENGTH_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.MAX_BASE_ADDRESS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.MAX_RECORD_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.MIN_BASE_ADDRESS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.MIN_RECORD_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.RECORD_LABEL_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.RECORD_LENGTH_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.RECORD_LENGTH_START;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.RECORD_STATUS_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.RESERVED_CHAR_POS;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.SYSTEM_CHARS_LENGTH;
import static org.culturegraph.mf.biblio.iso2709.Iso2709Constants.SYSTEM_CHARS_START;

import java.util.Arrays;

/**
 * Builds a record label for an ISO 2709:2008 record. The record label consists
 * of the first 24 octets of the record.
 * <p>
 *
 * @author Christoph Böhme
 *
 */
class LabelBuilder {

	private static final char DEFAULT_RECORD_STATUS = ' ';
	private static final char[] DEFAULT_IMPL_CODES = { ' ', ' ', ' ', ' ' };
	private static final char[] DEFAULT_SYSTEM_CHARS = { ' ', ' ', ' ' };
	private static final char DEFAULT_RESERVED_CHAR = ' ';

	private final Iso646ByteBuffer buffer;
	private final byte[] defaultLabel;

	LabelBuilder(final RecordFormat recordFormat) {
		buffer = new Iso646ByteBuffer(RECORD_LABEL_LENGTH);
		defaultLabel = buildDefaultLabel(recordFormat);
	}

	private byte[] buildDefaultLabel(final RecordFormat recordFormat) {
		writeRecordFormatToLabel(recordFormat);
		setRecordLength(MIN_RECORD_LENGTH);
		setRecordStatus(DEFAULT_RECORD_STATUS);
		setImplCodes(DEFAULT_IMPL_CODES);
		setBaseAddress(MIN_BASE_ADDRESS);
		setSystemChars(DEFAULT_SYSTEM_CHARS);
		setReservedChar(DEFAULT_RESERVED_CHAR);
		return Arrays.copyOf(buffer.getByteArray(), buffer.getLength());
	}

	private void writeRecordFormatToLabel(final RecordFormat recordFormat) {
		buffer.setWritePosition(INDICATOR_LENGTH_POS);
		buffer.writeInt(recordFormat.getIndicatorLength());
		buffer.setWritePosition(IDENTIFIER_LENGTH_POS);
		buffer.writeInt(recordFormat.getIdentifierLength());
		buffer.setWritePosition(FIELD_LENGTH_LENGTH_POS);
		buffer.writeInt(recordFormat.getFieldLengthLength());
		buffer.setWritePosition(FIELD_START_LENGTH_POS);
		buffer.writeInt(recordFormat.getFieldStartLength());
		buffer.setWritePosition(IMPL_DEFINED_PART_LENGTH_POS);
		buffer.writeInt(recordFormat.getImplDefinedPartLength());
	}

	void setRecordLength(final int recordLength) {
		assert recordLength >= MIN_RECORD_LENGTH;
		assert recordLength <= MAX_RECORD_LENGTH;
		buffer.setWritePosition(RECORD_LENGTH_START);
		buffer.writeInt(recordLength, RECORD_LENGTH_LENGTH);
	}

	void setRecordStatus(final char recordStatus) {
		buffer.setWritePosition(RECORD_STATUS_POS);
		buffer.writeChar(recordStatus);
	}

	void setImplCodes(final char[] implCodes) {
		assert implCodes.length == IMPL_CODES_LENGTH;
		buffer.setWritePosition(IMPL_CODES_START);
		buffer.writeChars(implCodes);
	}

	void setImplCode(final int index, final char value) {
		assert 0 <= index && index < IMPL_CODES_LENGTH;
		buffer.setWritePosition(IMPL_CODES_START + index);
		buffer.writeChar(value);
	}

	void setBaseAddress(final int baseAddress) {
		assert baseAddress >= MIN_BASE_ADDRESS;
		assert baseAddress <= MAX_BASE_ADDRESS;
		buffer.setWritePosition(BASE_ADDRESS_START);
		buffer.writeInt(baseAddress, BASE_ADDRESS_LENGTH);
	}

	void setSystemChars(final char[] systemChars) {
		assert systemChars.length == SYSTEM_CHARS_LENGTH;
		buffer.setWritePosition(SYSTEM_CHARS_START);
		buffer.writeChars(systemChars);
	}

	void setSystemChar(final int index, final char value) {
		assert 0 <= index && index < SYSTEM_CHARS_LENGTH;
		buffer.setWritePosition(SYSTEM_CHARS_LENGTH + index);
		buffer.writeChar(value);
	}

	void setReservedChar(final char reservedChar) {
		buffer.setWritePosition(RESERVED_CHAR_POS);
		buffer.writeChar(reservedChar);
	}

	void reset() {
		buffer.setWritePosition(0);
		buffer.writeBytes(defaultLabel);
	}

	void copyToBuffer(final byte[] destBuffer) {
		System.arraycopy(buffer.getByteArray(), 0, destBuffer, 0,
				buffer.getLength());
	}

	@Override
	public String toString() {
		return buffer.stringAt(0, buffer.getLength(), Iso646Constants.CHARSET);
	}

}