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Modules for processing bibliographic data
There is a newer version: 6.2.0
/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * 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.metafacture.biblio;

import org.metafacture.framework.FluxCommand;
import org.metafacture.framework.FormatException;
import org.metafacture.framework.MissingIdException;
import org.metafacture.framework.StreamReceiver;
import org.metafacture.framework.annotations.Description;
import org.metafacture.framework.annotations.In;
import org.metafacture.framework.annotations.Out;
import org.metafacture.framework.helpers.DefaultObjectPipe;

import java.util.regex.Pattern;

/**
 * Parses a raw Mab2 stream (utf-8 encoding assumed). Events are handled by a
 * {@link StreamReceiver}.
 *
 * @see StreamReceiver
 *
 * @author Markus Michael Geipel, Christoph Böhme
 *
 */
@Description("Parses a raw Mab2 stream (UTF-8 encoding expected).")
@In(String.class)
@Out(StreamReceiver.class)
@FluxCommand("decode-mab")
public final class MabDecoder extends DefaultObjectPipe {

    private static final String FIELD_END = "\u001e";
    private static final Pattern FIELD_PATTERN =
            Pattern.compile(FIELD_END, Pattern.LITERAL);
    private static final Pattern SUBFIELD_PATTERN =
            Pattern.compile("\u001f", Pattern.LITERAL);
    private static final String RECORD_END = "\u001d";

    private static final int FIELD_NAME_SIZE = 4;
    private static final int HEADER_SIZE = 24;
    private static final String LEADER = "Leader";
    private static final String TYPE = "type";
    private static final String INVALID_FORMAT = "Invalid MAB format";
    private static final String ID_TAG = "001 ";
    private static final int TAG_LENGTH = 4;

    /**
     * Creates an instance of {@link MabDecoder}.
     */
    public MabDecoder() {
    }

    @Override
    public void process(final String record) {
        assert !isClosed();

        if (record.trim().isEmpty()) {
            return;
        }

        getReceiver().startRecord(extractIdFromRecord(record));

        try {
            getReceiver().literal(LEADER, record.substring(0, HEADER_SIZE));
            getReceiver().literal(TYPE, String.valueOf(record.charAt(HEADER_SIZE - 1)));
            final String content = record.substring(HEADER_SIZE);
            for (final String part : FIELD_PATTERN.split(content)) {
                if (!part.startsWith(RECORD_END)) {
                    final String fieldName = part.substring(0, FIELD_NAME_SIZE).trim();
                    final String fieldContent = part.substring(FIELD_NAME_SIZE);
                    final String[] subFields = SUBFIELD_PATTERN.split(fieldContent);

                    if (subFields.length == 1) {
                        getReceiver().literal(fieldName, subFields[0]);
                    }
                    else {
                        getReceiver().startEntity(fieldName);

                        for (int i = 1; i < subFields.length; ++i) {
                            final String name = subFields[i].substring(0, 1);
                            final String value = subFields[i].substring(1);
                            getReceiver().literal(name, value);
                        }
                        getReceiver().endEntity();
                    }
                }
            }
        }
        catch (final IndexOutOfBoundsException e) {
            throw new FormatException("[" + record + "]", e);
        }

        getReceiver().endRecord();
    }

    private String extractIdFromRecord(final String record) {
        try {
            final int fieldEnd = record.indexOf(FIELD_END, HEADER_SIZE);
            if (record.substring(HEADER_SIZE, HEADER_SIZE + TAG_LENGTH).equals(ID_TAG)) {
                return record.substring(HEADER_SIZE + TAG_LENGTH, fieldEnd);
            }
            throw new MissingIdException(record);
        }
        catch (final IndexOutOfBoundsException e) {
            throw new FormatException(INVALID_FORMAT + record, e);
        }
    }

}