package eu.dnetlib.dhp.transformation;

import java.io.ByteArrayInputStream;
import java.io.StringWriter;
import java.util.Map;

import javax.xml.transform.stream.StreamSource;

import org.apache.spark.api.java.function.MapFunction;
import org.apache.spark.util.LongAccumulator;

import eu.dnetlib.dhp.model.mdstore.MetadataRecord;
import eu.dnetlib.dhp.transformation.functions.Cleaner;
import eu.dnetlib.dhp.transformation.vocabulary.Vocabulary;
import net.sf.saxon.s9api.*;

public class TransformFunction implements MapFunction<MetadataRecord, MetadataRecord> {

	private final LongAccumulator totalItems;
	private final LongAccumulator errorItems;
	private final LongAccumulator transformedItems;
	private final String transformationRule;
	private final Cleaner cleanFunction;

	private final long dateOfTransformation;

	public TransformFunction(
		LongAccumulator totalItems,
		LongAccumulator errorItems,
		LongAccumulator transformedItems,
		final String transformationRule,
		long dateOfTransformation,
		final Map<String, Vocabulary> vocabularies)
		throws Exception {
		this.totalItems = totalItems;
		this.errorItems = errorItems;
		this.transformedItems = transformedItems;
		this.transformationRule = transformationRule;
		this.dateOfTransformation = dateOfTransformation;
		cleanFunction = new Cleaner(vocabularies);
	}

	@Override
	public MetadataRecord call(MetadataRecord value) {
		totalItems.add(1);
		try {
			Processor processor = new Processor(false);
			processor.registerExtensionFunction(cleanFunction);
			final XsltCompiler comp = processor.newXsltCompiler();
			XsltExecutable xslt = comp
				.compile(new StreamSource(new ByteArrayInputStream(transformationRule.getBytes())));
			XdmNode source = processor
				.newDocumentBuilder()
				.build(new StreamSource(new ByteArrayInputStream(value.getBody().getBytes())));
			XsltTransformer trans = xslt.load();
			trans.setInitialContextNode(source);
			final StringWriter output = new StringWriter();
			Serializer out = processor.newSerializer(output);
			out.setOutputProperty(Serializer.Property.METHOD, "xml");
			out.setOutputProperty(Serializer.Property.INDENT, "yes");
			trans.setDestination(out);
			trans.transform();
			final String xml = output.toString();
			value.setBody(xml);
			value.setDateOfTransformation(dateOfTransformation);
			transformedItems.add(1);
			return value;
		} catch (Throwable e) {
			errorItems.add(1);
			return null;
		}
	}
}