Introduce string list attribute value getter method (#41)

data-model/src/main/java/org/hypertrace/core/datamodel/shared/SpanAttributeUtils.java

@@ -1,12 +1,20 @@
 package org.hypertrace.core.datamodel.shared;
 
+import static java.util.Collections.emptyList;
+import static java.util.stream.Collectors.toUnmodifiableList;
 import static org.hypertrace.core.datamodel.shared.AvroBuilderCache.fastNewBuilder;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import java.nio.ByteBuffer;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Spliterator;
+import java.util.Spliterators;
 import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
 import org.apache.avro.reflect.Nullable;
 import org.hypertrace.core.datamodel.AttributeValue;
 import org.hypertrace.core.datamodel.Attributes;
@@ -20,6 +28,7 @@
  * Span.
  */
 public class SpanAttributeUtils {
+  private static final ObjectMapper MAPPER = new ObjectMapper();
 
   public static boolean isLeafSpan(StructuredTraceGraph structuredTraceGraph, Event event) {
     List<Event> childEvents = structuredTraceGraph.getChildrenEvents(event);
@@ -106,6 +115,33 @@ public static boolean getBooleanAttribute(Event event, String attributeKey) {
     return Boolean.parseBoolean(value.getValue());
   }
 
+  public static List<String> getStringListAttribute(final Event event, final String attributeKey) {
+    final AttributeValue value = getAttributeValue(event, attributeKey);
+    if (value == null) {
+      return emptyList();
+    }
+
+    if (value.getValueList() != null && !value.getValueList().isEmpty()) {
+      return value.getValueList();
+    }
+
+    final String jsonValue = value.getValue();
+
+    try {
+      final JsonNode node = MAPPER.readTree(jsonValue);
+      if (node.isArray()) {
+        return StreamSupport.stream(
+                Spliterators.spliteratorUnknownSize(node.elements(), Spliterator.ORDERED), false)
+            .map(JsonNode::asText)
+            .collect(toUnmodifiableList());
+      }
+
+      return List.of(node.asText());
+    } catch (final JsonProcessingException e) {
+      return emptyList();
+    }
+  }
+
   /**
    * Utility method to get a single value from one of the given attributes. The first attribute
    * given in the list with non-null value will be used.

data-model/src/test/java/org/hypertrace/core/datamodel/shared/SpanAttributeUtilsTest.java

@@ -0,0 +1,66 @@
+package org.hypertrace.core.datamodel.shared;
+
+import static java.util.Collections.emptyList;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.util.List;
+import java.util.Map;
+import org.hypertrace.core.datamodel.AttributeValue;
+import org.hypertrace.core.datamodel.Attributes;
+import org.hypertrace.core.datamodel.Event;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class SpanAttributeUtilsTest {
+  @ParameterizedTest
+  @ValueSource(strings = {"\"Valid String\"", "[\"Valid String\"]"})
+  void testGetStringListAttribute(final String attributeValue) {
+    final Event event = mock(Event.class);
+    when(event.getAttributes())
+        .thenReturn(
+            Attributes.newBuilder()
+                .setAttributeMap(
+                    Map.of(
+                        "attributeKey",
+                        AttributeValue.newBuilder().setValue(attributeValue).build()))
+                .build());
+    final List<String> result = SpanAttributeUtils.getStringListAttribute(event, "attributeKey");
+    assertEquals(List.of("Valid String"), result);
+  }
+
+  @ParameterizedTest
+  @ValueSource(strings = {"Invalid JSON", "[]"})
+  void testGetStringListAttribute_emptyList(final String attributeValue) {
+    final Event event = mock(Event.class);
+    when(event.getAttributes())
+        .thenReturn(
+            Attributes.newBuilder()
+                .setAttributeMap(
+                    Map.of(
+                        "attributeKey",
+                        AttributeValue.newBuilder().setValue(attributeValue).build()))
+                .build());
+    final List<String> result = SpanAttributeUtils.getStringListAttribute(event, "attributeKey");
+    assertEquals(emptyList(), result);
+  }
+
+  @Test
+  void testGetStringListAttribute_multiValuedList() {
+    final Event event = mock(Event.class);
+    when(event.getAttributes())
+        .thenReturn(
+            Attributes.newBuilder()
+                .setAttributeMap(
+                    Map.of(
+                        "attributeKey",
+                        AttributeValue.newBuilder()
+                            .setValue("[\"value1\", \"value2\", 3]")
+                            .build()))
+                .build());
+    final List<String> result = SpanAttributeUtils.getStringListAttribute(event, "attributeKey");
+    assertEquals(List.of("value1", "value2", "3"), result);
+  }
+}