Add support for maximum or average values in metrics

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/model/ElementFormatter.java

@@ -426,4 +426,17 @@
     private void add(final ListBoxModel options, final Baseline baseline) {
         options.add(getDisplayName(baseline), baseline.name());
     }
+
+    /**
+     * Returns all available aggregation modes as a {@link ListBoxModel}.
+     *
+     * @return the aggregation modes in a {@link ListBoxModel}
+     */
+    public ListBoxModel getAggregationItems() {
+        var options = new ListBoxModel();
+        for (MetricAggregation aggregation : MetricAggregation.values()) {
+            options.add(aggregation.name(), aggregation.name());
+        }
+        return options;
+    }
 }

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/model/MetricAggregation.java

@@ -0,0 +1,40 @@
+package io.jenkins.plugins.coverage.metrics.model;
+
+import edu.hm.hafner.coverage.Metric;
+
+/**
+ * Defines the aggregation mode for software metrics that can be aggregated in different ways (e.g., cyclomatic
+ * complexity can be reported as total, maximum, or average). For coverage metrics, this aggregation is not applicable
+ * and will be ignored.
+ *
+ * @author Akash Manna
+ */
+public enum MetricAggregation {
+    /** The total value of the metric (sum of all values). */
+    TOTAL,
+    /** The maximum value of the metric. */
+    MAXIMUM,
+    /** The average value of the metric. */
+    AVERAGE;
+
+    /**
+     * Returns whether the specified metric supports aggregation modes.
+     *
+     * @param metric
+     *         the metric to check
+     *
+     * @return {@code true} if the metric supports aggregation modes, {@code false} otherwise
+     */
+    public static boolean isSupported(final Metric metric) {
+        return !metric.isCoverage();
+    }
+
+    /**
+     * Returns the default aggregation mode.
+     *
+     * @return the default aggregation mode
+     */
+    public static MetricAggregation getDefault() {
+        return TOTAL;
+    }
+}

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/steps/CoverageQualityGate.java

@@ -14,6 +14,7 @@
 
 import io.jenkins.plugins.coverage.metrics.model.Baseline;
 import io.jenkins.plugins.coverage.metrics.model.ElementFormatter;
+import io.jenkins.plugins.coverage.metrics.model.MetricAggregation;
 import io.jenkins.plugins.util.JenkinsFacade;
 import io.jenkins.plugins.util.QualityGate;
 
@@ -24,6 +25,7 @@
  *
  * @author Johannes Walter
  */
+@SuppressWarnings("PMD.DataClass") 
 public class CoverageQualityGate extends QualityGate {
     @Serial
     private static final long serialVersionUID = -397278599489426668L;
@@ -32,6 +34,7 @@
 
     private final Metric metric;
     private Baseline baseline = Baseline.PROJECT;
+    private MetricAggregation aggregation = MetricAggregation.TOTAL;
 
     /**
      * Creates a new instance of {@link CoverageQualityGate}.
@@ -62,6 +65,16 @@
         setCriticality(criticality);
     }
 
+    CoverageQualityGate(final double threshold, final Metric metric,
+            final Baseline baseline, final QualityGateCriticality criticality,
+            final MetricAggregation aggregation) {
+        this(metric, threshold);
+
+        setBaseline(baseline);
+        setCriticality(criticality);
+        setAggregation(aggregation);
+    }
+
     /**
      * Sets the baseline that will be used for the quality gate evaluation.
      *
@@ -73,13 +86,31 @@
         this.baseline = baseline;
     }
 
+    /**
+     * Sets the aggregation mode for software metrics (total, maximum, or average). This is only applicable for
+     * software metrics like cyclomatic complexity. For coverage metrics, this setting is ignored.
+     *
+     * @param aggregation
+     *         the aggregation mode to use
+     */
+    @DataBoundSetter
+    public final void setAggregation(final MetricAggregation aggregation) {
+        if (MetricAggregation.isSupported(metric)) {
+            this.aggregation = aggregation;
+        }
+    }
+
     /**
      * Returns a human-readable name of the quality gate.
      *
      * @return a human-readable name
      */
     @Override
     public String getName() {
+        if (MetricAggregation.isSupported(metric) && aggregation != MetricAggregation.TOTAL) {
+            return "%s - %s (%s)".formatted(FORMATTER.getDisplayName(getBaseline()),
+                    FORMATTER.getDisplayName(getMetric()), aggregation);
+        }
         return "%s - %s".formatted(FORMATTER.getDisplayName(getBaseline()),
                 FORMATTER.getDisplayName(getMetric()));
     }
@@ -92,6 +123,10 @@
         return baseline;
     }
 
+    public MetricAggregation getAggregation() {
+        return aggregation;
+    }
+
     /**
      * Descriptor of the {@link CoverageQualityGate}.
      */
@@ -141,5 +176,19 @@
             }
             return new ListBoxModel();
         }
+
+        /**
+         * Returns a model with all {@link MetricAggregation aggregation modes}.
+         *
+         * @return a model with all {@link MetricAggregation aggregation modes}.
+         */
+        @POST
+        @SuppressWarnings("unused") // used by Stapler view data binding
+        public ListBoxModel doFillAggregationItems() {
+            if (jenkins.hasPermission(Jenkins.READ)) {
+                return FORMATTER.getAggregationItems();
+            }
+            return new ListBoxModel();
+        }
     }
 }

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/steps/CoverageQualityGateEvaluator.java

@@ -1,10 +1,20 @@
 package io.jenkins.plugins.coverage.metrics.steps;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Locale;
+import java.util.Optional;
+import java.util.stream.Stream;
 
+import edu.hm.hafner.coverage.Metric;
+import edu.hm.hafner.coverage.Node;
+import edu.hm.hafner.coverage.Value;
+import edu.umd.cs.findbugs.annotations.CheckForNull;
+
+import io.jenkins.plugins.coverage.metrics.model.Baseline;
 import io.jenkins.plugins.coverage.metrics.model.CoverageStatistics;
 import io.jenkins.plugins.coverage.metrics.model.ElementFormatter;
+import io.jenkins.plugins.coverage.metrics.model.MetricAggregation;
 import io.jenkins.plugins.util.QualityGateEvaluator;
 import io.jenkins.plugins.util.QualityGateResult;
 import io.jenkins.plugins.util.QualityGateStatus;
@@ -17,18 +27,36 @@
 class CoverageQualityGateEvaluator extends QualityGateEvaluator<CoverageQualityGate> {
     private static final ElementFormatter FORMATTER = new ElementFormatter();
     private final CoverageStatistics statistics;
+    @CheckForNull
+    private final Node rootNode;
 
     CoverageQualityGateEvaluator(final Collection<? extends CoverageQualityGate> qualityGates,
             final CoverageStatistics statistics) {
+        this(qualityGates, statistics, null);
+    }
+
+    CoverageQualityGateEvaluator(final Collection<? extends CoverageQualityGate> qualityGates,
+            final CoverageStatistics statistics, @CheckForNull final Node rootNode) {
         super(qualityGates);
 
         this.statistics = statistics;
+        this.rootNode = rootNode;
     }
 
     @Override
     protected void evaluate(final CoverageQualityGate qualityGate, final QualityGateResult result) {
         var baseline = qualityGate.getBaseline();
-        var possibleValue = statistics.getValue(baseline, qualityGate.getMetric());
+        var metric = qualityGate.getMetric();
+        var aggregation = qualityGate.getAggregation();
+
+        Optional<Value> possibleValue;
+        if (MetricAggregation.isSupported(metric) && aggregation != MetricAggregation.TOTAL && rootNode != null) {
+            possibleValue = computeAggregatedValue(rootNode, metric, aggregation, baseline);
+        }
+        else {
+            possibleValue = statistics.getValue(baseline, metric);
+        }
+
         if (possibleValue.isPresent()) {
             var actualValue = possibleValue.get();
             var status = actualValue.isOutOfValidRange(
@@ -39,4 +67,91 @@
             result.add(qualityGate, QualityGateStatus.INACTIVE, "n/a");
         }
     }
+
+    /**
+     * Computes an aggregated value (maximum or average) for a metric from the node tree.
+     *
+     * @param node
+     *         the root node to compute from
+     * @param metric
+     *         the metric to compute
+     * @param aggregation
+     *         the aggregation mode (MAXIMUM or AVERAGE)
+     * @param baseline
+     *         the baseline (currently only PROJECT is supported for custom aggregation)
+     *
+     * @return the computed value, or empty if not computable
+     */
+    private Optional<Value> computeAggregatedValue(final Node node, final Metric metric,
+            final MetricAggregation aggregation, final Baseline baseline) {
+        if (baseline != Baseline.PROJECT) {
+            return statistics.getValue(baseline, metric);
+        }
+
+        var allValues = collectLeafValues(node, metric).toList();
+
+        if (allValues.isEmpty()) {
+            return Optional.empty();
+        }
+
+        if (aggregation == MetricAggregation.MAXIMUM) {
+            return allValues.stream().reduce(Value::max);
+        }
+        else if (aggregation == MetricAggregation.AVERAGE) {
+            return computeAverage(allValues);
+        }
+
+        return Optional.empty();
+    }
+
+    /**
+     * Collects all leaf values for a metric from a node tree. For metrics computed at the method level (like
+     * complexity), this collects values from all methods. For class-level metrics, it collects from all classes.
+     *
+     * @param node
+     *         the node to start from
+     * @param metric
+     *         the metric to collect
+     *
+     * @return a stream of all leaf values
+     */
+    private Stream<Value> collectLeafValues(final Node node, final Metric metric) {
+        Stream<Value> nodeValue = node.getValue(metric).stream();
+
+        Stream<Value> childValues = node.getChildren().stream()
+                .flatMap(child -> collectLeafValues(child, metric));
+
+        if (node.getMetric() == Metric.METHOD
+                || node.getMetric() == Metric.CLASS) {
+            return Stream.concat(nodeValue, childValues);
+        }
+
+        var childValuesList = childValues.toList();
+        return childValuesList.isEmpty() ? nodeValue : childValuesList.stream();
+    }
+
+    /**
+     * Computes the average of a list of values. For integer metrics like complexity, this computes the arithmetic
+     * mean. For coverage metrics, this computes the average percentage.
+     *
+     * @param values
+     *         the values to average
+     *
+     * @return the average value, or empty if no values
+     */
+    private Optional<Value> computeAverage(final List<Value> values) {
+        if (values.isEmpty()) {
+            return Optional.empty();
+        }
+
+        var sum = values.stream().reduce(Value::add);
+        if (sum.isEmpty()) {
+            return Optional.empty();
+        }
+
+        var metric = values.get(0).getMetric();
+        var totalValue = sum.get();
+
+        return Optional.of(new Value(metric, totalValue.asDouble() / values.size()));
+    }
 }

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/steps/CoverageReporter.java

@@ -68,7 +68,7 @@ private CoverageBuildAction computeActionWithoutHistory(
             final FilteredLog log) throws InterruptedException {
         var statistics = new CoverageStatistics(rootNode.aggregateValues(),
                 List.of(), List.<Difference>of(), List.of(), EMPTY_VALUES, List.of());
-        var evaluator = new CoverageQualityGateEvaluator(qualityGates, statistics);
+        var evaluator = new CoverageQualityGateEvaluator(qualityGates, statistics, rootNode);
         var qualityGateStatus = evaluator.evaluate(notifier, log);
 
         paintSourceFiles(build, workspace, sourceCodeEncoding, sourceCodeRetention, id, rootNode,
@@ -122,7 +122,7 @@ private CoverageBuildAction computeCoverageBasedOnReferenceBuild(
 
         var statistics = new CoverageStatistics(overallValues, overallDelta,
                 modifiedLinesValues, modifiedLinesDelta, modifiedFilesValues, modifiedFilesDelta);
-        var evaluator = new CoverageQualityGateEvaluator(qualityGates, statistics);
+        var evaluator = new CoverageQualityGateEvaluator(qualityGates, statistics, rootNode);
         var qualityGateResult = evaluator.evaluate(notifier, log);
 
         var filesToStore = computePaintedFiles(rootNode, sourceCodeRetention, log, modifiedLinesCoverageRoot);

plugin/src/main/java/io/jenkins/plugins/coverage/metrics/steps/CoverageXmlStream.java

@@ -48,6 +48,7 @@
  */
 @SuppressWarnings("PMD.CouplingBetweenObjects")
 class CoverageXmlStream extends AbstractXmlStream<Node> {
+    private static final String LEGACY_COMPLEXITY_MAXIMUM = "COMPLEXITY_MAXIMUM";
     private static final Collector<CharSequence, ?, String> ARRAY_JOINER = Collectors.joining(", ", "[", "]");
 
     private static String[] toArray(final String value) {
@@ -109,14 +110,30 @@
 
         xStream.registerConverter(new FractionConverter());
         xStream.registerConverter(new SimpleConverter<>(Value.class, Value::serialize, Value::valueOf));
-        xStream.registerConverter(new SimpleConverter<>(Metric.class, Metric::name, Metric::valueOf));
+        xStream.registerConverter(new SimpleConverter<>(Metric.class, Metric::name, CoverageXmlStream::metricValueOf));
     }
 
     @Override
     protected Node createDefaultValue() {
         return new ModuleNode("Empty");
     }
 
+    /**
+     * Converts a string to a {@link Metric} value. Handles legacy metric names like COMPLEXITY_MAXIMUM by mapping
+     * them to the new metric names.
+     *
+     * @param metricName
+     *         the name of the metric
+     *
+     * @return the metric value
+     */
+    private static Metric metricValueOf(final String metricName) {
+        if (LEGACY_COMPLEXITY_MAXIMUM.equals(metricName)) {
+            return Metric.CYCLOMATIC_COMPLEXITY;
+        }
+        return Metric.valueOf(metricName);
+    }
+
     /**
      * {@link Converter} for {@link Fraction} instances so that only the values will be serialized. After reading the
      * values back from the stream, the string representation will be converted to an actual instance again.

plugin/src/main/resources/io/jenkins/plugins/coverage/metrics/steps/CoverageQualityGate/config.jelly

@@ -13,6 +13,10 @@
     <f:select/>
   </f:entry>
 
+  <f:entry title="${%title.aggregation}" field="aggregation">
+    <f:select/>
+  </f:entry>
+
   <f:entry title="${%title.warning}" field="criticality">
     <f:select/>
   </f:entry>

plugin/src/main/resources/io/jenkins/plugins/coverage/metrics/steps/CoverageQualityGate/config.properties

@@ -1,4 +1,5 @@
 title.threshold=Threshold
 title.baseline=Baseline
 title.metric=Metric
+title.aggregation=Aggregation
 title.warning=Step or Build Result