Refactored LightGBMConverter class

pmml-rexp-lightgbm/src/main/java/org/jpmml/rexp/lightgbm/LightGBMConverter.java

@@ -22,38 +22,78 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Collections;
+import java.util.List;
+import java.util.Map;
 
-import org.dmg.pmml.PMML;
+import org.dmg.pmml.mining.MiningModel;
+import org.jpmml.converter.Feature;
+import org.jpmml.converter.Label;
+import org.jpmml.converter.Schema;
 import org.jpmml.lightgbm.GBDT;
 import org.jpmml.lightgbm.LightGBMUtil;
-import org.jpmml.rexp.Converter;
+import org.jpmml.rexp.ModelConverter;
 import org.jpmml.rexp.REnvironment;
 import org.jpmml.rexp.RExpEncoder;
 import org.jpmml.rexp.RRaw;
 
-public class LightGBMConverter extends Converter<REnvironment> {
+public class LightGBMConverter extends ModelConverter<REnvironment> {
+
+	private GBDT gbdt = null;
+
 
 	public LightGBMConverter(REnvironment environment){
 		super(environment);
 	}
 
 	@Override
-	public PMML encodePMML(RExpEncoder encoder){
+	public void encodeSchema(RExpEncoder encoder){
+		GBDT gbdt = ensureGBDT();
+
+		Schema schema = gbdt.encodeSchema(null, null, encoder);
+
+		Label label = schema.getLabel();
+		List<? extends Feature> features = schema.getFeatures();
+
+		encoder.setLabel(label);
+
+		for(Feature feature : features){
+			encoder.addFeature(feature);
+		}
+	}
+
+	@Override
+	public MiningModel encodeModel(Schema schema){
+		GBDT gbdt = ensureGBDT();
+
+		// XXX
+		Map<String, Object> options = Collections.emptyMap();
+
+		Schema lgbmSchema = gbdt.toLightGBMSchema(schema);
+
+		return gbdt.encodeModel(options, lgbmSchema);
+	}
+
+	private GBDT ensureGBDT(){
+
+		if(this.gbdt == null){
+			this.gbdt = loadGBDT();
+		}
+
+		return this.gbdt;
+	}
+
+	private GBDT loadGBDT(){
 		REnvironment environment = getObject();
 
 		RRaw raw = (RRaw)environment.findVariable("raw");
 		if(raw == null){
 			throw new IllegalArgumentException();
 		}
 
-		GBDT gbdt;
-
 		try(InputStream is = new ByteArrayInputStream(raw.getValue())){
-			gbdt = LightGBMUtil.loadGBDT(is);
+			return LightGBMUtil.loadGBDT(is);
 		} catch(IOException ioe){
 			throw new IllegalArgumentException(ioe);
 		}
-
-		return gbdt.encodePMML(Collections.emptyMap(), null, null);
 	}
 }