Merge pull request #406 from LiUSemWeb/405-dedicated-endpoints-for-query-processing-introspection

405 dedicated endpoints for query processing introspection

Author: hartig

hefquin-base/src/main/java/se/liu/ida/hefquin/base/utils/StatsPrinterJSON.java

@@ -0,0 +1,133 @@
+package se.liu.ida.hefquin.base.utils;
+
+import java.io.PrintStream;
+import java.util.List;
+
+import org.apache.jena.atlas.json.JsonObject;
+import org.apache.jena.atlas.json.JsonString;
+import org.apache.jena.atlas.json.JsonValue;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.jena.atlas.json.JsonArray;
+import org.apache.jena.atlas.json.JsonBoolean;
+import org.apache.jena.atlas.json.JsonNumber;
+import org.apache.jena.atlas.json.JsonNull;
+
+/**
+ * A utility class for converting and printing {@link Stats} objects in JSON format.
+ */
+public class StatsPrinterJSON
+{
+	/**
+	 * Converts and prints the given {@link Stats} object as JSON to the specified {@link PrintStream}.
+	 *
+	 * @param s         the {@link Stats} object to print
+	 * @param out       the output stream to print to
+	 * @param recursive whether nested {@link Stats} entries should be printed recursively
+	 */
+	public static void print( final Stats s, final PrintStream out, final boolean recursive ) {
+		final JsonObject stats = statsAsJson( s, recursive );
+		out.print( stats.toString() );
+	}
+
+	/**
+	 * Converts the given {@link Stats} object as JSON. Nested {@link Stats} entries will be converted recursively.
+	 *
+	 * @param s the {@link Stats} object to convert
+	 */
+	public static JsonObject statsAsJson( final Stats s ) {
+		return statsAsJson( s, true );
+	}
+
+	/**
+	 * Converts the given {@link Stats} object to a JSON object.
+	 *
+	 * @param s         the {@link Stats} object to convert
+	 * @param recursive whether nested {@link Stats} entries should be converted recursively
+	 * @return a JSON object representation of the {@link Stats}
+	 */
+	public static JsonObject statsAsJson( final Stats s, final boolean recursive ) {
+		final JsonObject stats = new JsonObject();
+		if ( s == null || s.isEmpty() ) {
+			return stats;
+		}
+		for ( final String entryName : s.getEntryNames() ) {
+			final Object entry = s.getEntry( entryName );
+			stats.put( entryName, asJson( entry, recursive ) );
+		}
+
+		return stats;
+	}
+
+	/**
+	 * Converts the given {@link Stats} object to a JSON object.
+	 *
+	 * @param s         the {@link Stats} object to convert
+	 * @param recursive whether nested {@link Stats} entries should be converted recursively
+	 * @return a JSON object representation of the {@link Stats}
+	 */
+	private static JsonValue asJson( final Object entry, final boolean recursive ) {
+		if ( entry == null ) {
+			return JsonNull.instance;
+		}
+
+		if ( entry instanceof Stats stats ) {
+			if ( recursive ) {
+				return statsAsJson( stats, recursive );
+			}
+			return new JsonString( "..." );
+		}
+
+		// List of objects
+		if ( entry instanceof List<?> list ) {
+			final JsonArray jsonArray = new JsonArray();
+			for ( final Object o : list ) {
+				jsonArray.add( asJson( o, recursive ) );
+			}
+			return jsonArray;
+		}
+
+		// Array of objects
+		if ( entry instanceof Object[] array ) {
+			final JsonArray arr = new JsonArray();
+			for ( Object o : array ) {
+				arr.add( asJson( o, recursive ) );
+			}
+			return arr;
+		}
+
+		// Array of primitives
+		if ( entry instanceof int[] a ) {
+			return asJson( ArrayUtils.toObject( a ), recursive );
+		}
+		if ( entry instanceof long[] a ) {
+			return asJson( ArrayUtils.toObject( a ), recursive );
+		}
+		if ( entry instanceof double[] a ) {
+			return asJson( ArrayUtils.toObject( a ), recursive );
+		}
+		if ( entry instanceof float[] a ) {
+			return asJson( ArrayUtils.toObject( a ), recursive );
+		}
+		if ( entry instanceof boolean[] a ) {
+			return asJson( ArrayUtils.toObject( a ), recursive );
+		}
+
+		// JSON primitives
+		if ( entry instanceof Boolean b ) {
+			return new JsonBoolean( b );
+		}
+
+		if ( entry instanceof Number num ) {
+			if ( num instanceof Double d && (Double.isNaN( d ) || Double.isInfinite( d )) ) {
+				return new JsonString( d.toString() );
+			}
+			if ( num instanceof Float f && (Float.isNaN( f ) || Float.isInfinite( f )) ) {
+				return new JsonString( f.toString() );
+			}
+			return JsonNumber.value( num.doubleValue() );
+		}
+
+		// default to string
+		return new JsonString( entry.toString() );
+	}
+}