fix: add calculateWeightedEffort method to DtoUtils and refactor EffortRatingDTO to use it

Author: Predixx

src/main/java/de/tum/cit/aet/ai/dto/EffortRatingDTO.java

@@ -1,6 +1,7 @@
 package de.tum.cit.aet.ai.dto;
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import de.tum.cit.aet.analysis.util.DtoUtils;
 
 /**
  * Result of LLM-based effort rating for a commit chunk.
@@ -32,8 +33,7 @@ public record EffortRatingDTO(
      * Normalizes to roughly match raw effort score but considers quality.
      */
     public double weightedEffort() {
-        double qualityMultiplier = 0.5 + (0.3 * complexity / 10.0) + (0.2 * novelty / 10.0);
-        return effortScore * qualityMultiplier;
+        return DtoUtils.calculateWeightedEffort(effortScore, complexity, novelty);
     }
 
     /**

src/main/java/de/tum/cit/aet/analysis/util/DtoUtils.java

@@ -19,4 +19,19 @@ private DtoUtils() {
     public static int calculateLinesChanged(int linesAdded, int linesDeleted) {
         return linesAdded + linesDeleted;
     }
+
+    /**
+     * Calculates a weighted effort score.
+     * Formula: effortScore * (0.5 + 0.3*complexity + 0.2*novelty) / 10
+     * Normalizes to roughly match raw effort score but considers quality.
+     *
+     * @param effortScore raw effort score (1-10)
+     * @param complexity  technical complexity (1-10)
+     * @param novelty     originality of the work (1-10)
+     * @return weighted effort score
+     */
+    public static double calculateWeightedEffort(double effortScore, double complexity, double novelty) {
+        double qualityMultiplier = 0.5 + (0.3 * complexity / 10.0) + (0.2 * novelty / 10.0);
+        return effortScore * qualityMultiplier;
+    }
 }