/**
*
*/
package com.github.jsonldjava.sesame;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import org.openrdf.model.Model;
import org.openrdf.model.Namespace;
import org.openrdf.model.Statement;
import org.openrdf.model.impl.LinkedHashModel;
import org.openrdf.rio.RDFFormat;
import org.openrdf.rio.RDFHandlerException;
import org.openrdf.rio.RDFWriter;
import org.openrdf.rio.helpers.BasicWriterSettings;
import org.openrdf.rio.helpers.JSONLDMode;
import org.openrdf.rio.helpers.JSONLDSettings;
import org.openrdf.rio.helpers.RDFWriterBase;
import org.openrdf.rio.helpers.StatementCollector;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.github.jsonldjava.core.JsonLdError;
import com.github.jsonldjava.core.JsonLdOptions;
import com.github.jsonldjava.core.JsonLdProcessor;
import com.github.jsonldjava.utils.JsonUtils;
/**
* @author Peter Ansell p_ansell@yahoo.com
*
*/
public class SesameJSONLDWriter extends RDFWriterBase implements RDFWriter {
private final Model model = new LinkedHashModel();
private final StatementCollector statementCollector = new StatementCollector(model);
private final Writer writer;
/**
* Create a SesameJSONLDWriter using a {@link java.io.OutputStream}
*
* @param outputStream
* The OutputStream to write to.
*/
public SesameJSONLDWriter(OutputStream outputStream) {
this(new BufferedWriter(new OutputStreamWriter(outputStream, Charset.forName("UTF-8"))));
}
/**
* Create a SesameJSONLDWriter using a {@link java.io.Writer}
*
* @param writer
* The Writer to write to.
*/
public SesameJSONLDWriter(Writer writer) {
this.writer = writer;
}
@Override
public void handleNamespace(String prefix, String uri) throws RDFHandlerException {
model.setNamespace(prefix, uri);
}
@Override
public void startRDF() throws RDFHandlerException {
statementCollector.clear();
model.clear();
}
@Override
public void endRDF() throws RDFHandlerException {
final SesameRDFParser serialiser = new SesameRDFParser();
try {
Object output = JsonLdProcessor.fromRDF(model, serialiser);
final JSONLDMode mode = getWriterConfig().get(JSONLDSettings.JSONLD_MODE);
final JsonLdOptions opts = new JsonLdOptions();
// opts.addBlankNodeIDs =
// getWriterConfig().get(BasicParserSettings.PRESERVE_BNODE_IDS);
opts.setUseRdfType(getWriterConfig().get(JSONLDSettings.USE_RDF_TYPE));
opts.setUseNativeTypes(getWriterConfig().get(JSONLDSettings.USE_NATIVE_TYPES));
// opts.optimize = getWriterConfig().get(JSONLDSettings.OPTIMIZE);
if (mode == JSONLDMode.EXPAND) {
output = JsonLdProcessor.expand(output, opts);
}
// TODO: Implement inframe in JSONLDSettings
final Object inframe = null;
if (mode == JSONLDMode.FLATTEN) {
output = JsonLdProcessor.flatten(output, inframe, opts);
}
if (mode == JSONLDMode.COMPACT) {
final Map<String, Object> ctx = new LinkedHashMap<String, Object>();
addPrefixes(ctx, model.getNamespaces());
final Map<String, Object> localCtx = new HashMap<String, Object>();
localCtx.put("@context", ctx);
output = JsonLdProcessor.compact(output, localCtx, opts);
}
if (getWriterConfig().get(BasicWriterSettings.PRETTY_PRINT)) {
JsonUtils.writePrettyPrint(writer, output);
} else {
JsonUtils.write(writer, output);
}
} catch (final JsonLdError e) {
throw new RDFHandlerException("Could not render JSONLD", e);
} catch (final JsonGenerationException e) {
throw new RDFHandlerException("Could not render JSONLD", e);
} catch (final JsonMappingException e) {
throw new RDFHandlerException("Could not render JSONLD", e);
} catch (final IOException e) {
throw new RDFHandlerException("Could not render JSONLD", e);
}
}
@Override
public void handleStatement(Statement st) throws RDFHandlerException {
statementCollector.handleStatement(st);
}
@Override
public void handleComment(String comment) throws RDFHandlerException {
}
@Override
public RDFFormat getRDFFormat() {
return RDFFormat.JSONLD;
}
private static void addPrefixes(Map<String, Object> ctx, Set<Namespace> namespaces) {
for (final Namespace ns : namespaces) {
ctx.put(ns.getPrefix(), ns.getName());
}
}
}