001/*
002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Nuxeo - initial API and implementation
018 *
019 * $Id$
020 */
021
022package org.nuxeo.ecm.core.convert.extension;
023
024import java.io.Serializable;
025import java.util.ArrayList;
026import java.util.List;
027import java.util.Map;
028
029import org.nuxeo.ecm.core.api.blobholder.BlobHolder;
030import org.nuxeo.ecm.core.convert.api.ConversionException;
031import org.nuxeo.ecm.core.convert.service.ConversionServiceImpl;
032import org.nuxeo.ecm.core.convert.service.MimeTypeTranslationHelper;
033import org.nuxeo.runtime.api.Framework;
034
035/**
036 * Specific {@link Converter} implementation that acts as a converters chain.
037 * <p>
038 * The chain can be:
039 * <ul>
040 * <li>a chain of mime-types
041 * <li>a chain of converter names
042 * </ul>
043 * <p>
044 * This depends on the properties of the descriptor.
045 *
046 * @author tiry
047 */
048public class ChainedConverter implements Converter {
049
050    protected boolean subConvertersBased = false;
051
052    protected List<String> steps = new ArrayList<String>();
053
054    protected List<String> subConverters = new ArrayList<String>();
055
056    public ChainedConverter() {
057        subConvertersBased = false;
058        subConverters = null;
059    }
060
061    public ChainedConverter(List<String> subConverters) {
062        subConvertersBased = true;
063        this.subConverters = subConverters;
064        steps = null;
065    }
066
067    @Override
068    public BlobHolder convert(BlobHolder blobHolder, Map<String, Serializable> parameters) throws ConversionException {
069
070        if (subConvertersBased) {
071            return convertBasedSubConverters(blobHolder, parameters);
072        } else {
073            return convertBasedOnMimeTypes(blobHolder, parameters);
074        }
075    }
076
077    protected BlobHolder convertBasedSubConverters(BlobHolder blobHolder, Map<String, Serializable> parameters)
078            throws ConversionException {
079        String srcMT = blobHolder.getBlob().getMimeType();
080        BlobHolder result = blobHolder;
081        for (String converterName : subConverters) {
082            ConverterDescriptor desc = ConversionServiceImpl.getConverterDescriptor(converterName);
083            if (!desc.getSourceMimeTypes().contains(srcMT)) {
084                throw new ConversionException("Conversion Chain is not well defined");
085            }
086            Converter converter = ConversionServiceImpl.getConverter(converterName);
087            result = converter.convert(result, parameters);
088            srcMT = desc.getDestinationMimeType();
089        }
090        return result;
091    }
092
093    /**
094     * Tries to find a chain of converters that fits the mime-types chain.
095     */
096    protected BlobHolder convertBasedOnMimeTypes(BlobHolder blobHolder, Map<String, Serializable> parameters)
097            throws ConversionException {
098        String srcMT = blobHolder.getBlob().getMimeType();
099        BlobHolder result = blobHolder;
100        for (String dstMT : steps) {
101            String converterName = Framework.getService(MimeTypeTranslationHelper.class).getConverterName(srcMT, dstMT);
102            if (converterName == null) {
103                throw new ConversionException(
104                        "Chained conversion error : unable to find converter between " + srcMT + " and " + dstMT);
105            }
106            Converter converter = ConversionServiceImpl.getConverter(converterName);
107            result = converter.convert(result, parameters);
108            srcMT = dstMT;
109        }
110        return result;
111    }
112
113    @Override
114    public void init(ConverterDescriptor descriptor) {
115        if (!subConvertersBased) {
116            steps.addAll(descriptor.getSteps());
117            steps.add(descriptor.getDestinationMimeType());
118        } else {
119            ConverterDescriptor fconv = ConversionServiceImpl.getConverterDescriptor(subConverters.get(0));
120            ConverterDescriptor lconv = ConversionServiceImpl.getConverterDescriptor(subConverters.get(subConverters.size() - 1));
121
122            descriptor.sourceMimeTypes = fconv.sourceMimeTypes;
123            descriptor.destinationMimeType = lconv.destinationMimeType;
124        }
125    }
126
127    public List<String> getSteps() {
128        return steps;
129    }
130
131    /**
132     * Returns the sub converters of this chained converter.
133     *
134     * @since 5.9.2
135     */
136    public List<String> getSubConverters() {
137        return subConverters;
138    }
139
140    /**
141     * Returns true if this chained converter is sub converters based, false otherwise.
142     *
143     * @since 5.9.4
144     */
145    public boolean isSubConvertersBased() {
146        return subConvertersBased;
147    }
148}