Drop unnecessary abstraction

Author: damianmalczewski

problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/AbstractProblemResolverStore.java

@@ -14,9 +14,18 @@
  */
 package io.github.problem4j.spring.web;
 
+import static io.github.problem4j.spring.web.util.HierarchyTraversalMode.SUPERCLASS;
+
 import io.github.problem4j.spring.web.resolver.ProblemResolver;
 import io.github.problem4j.spring.web.util.ClassDistanceEvaluation;
+import io.github.problem4j.spring.web.util.GraphClassDistanceEvaluation;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
 
 /**
  * {@link ProblemResolverStore} implementation evaluates resolved based on class and its
@@ -25,7 +34,10 @@
  * <p>Resolvers are matched to exceptions by assignability, preferring the most specific exception
  * type.
  */
-public class DefaultProblemResolverStore extends AbstractProblemResolverStore {
+public class DefaultProblemResolverStore implements ProblemResolverStore {
+
+  private final Map<Class<? extends Exception>, ProblemResolver> resolvers;
+  private final ClassDistanceEvaluation classDistanceEvaluation;
 
   /**
    * Creates a new store initialized with the given resolvers.
@@ -34,7 +46,7 @@ public class DefaultProblemResolverStore extends AbstractProblemResolverStore {
    * @throws NullPointerException if any resolver or its exception class is {@code null}
    */
   public DefaultProblemResolverStore(List<ProblemResolver> problemResolvers) {
-    super(problemResolvers);
+    this(problemResolvers, new GraphClassDistanceEvaluation(SUPERCLASS));
   }
 
   /**
@@ -48,6 +60,35 @@ public DefaultProblemResolverStore(List<ProblemResolver> problemResolvers) {
    */
   public DefaultProblemResolverStore(
       List<ProblemResolver> problemResolvers, ClassDistanceEvaluation classDistanceEvaluation) {
-    super(problemResolvers, classDistanceEvaluation);
+    Map<Class<? extends Exception>, ProblemResolver> copy = new HashMap<>(problemResolvers.size());
+    problemResolvers.forEach(
+        resolver -> copy.put(resolver.getExceptionClass(), Objects.requireNonNull(resolver)));
+    this.resolvers = Map.copyOf(copy);
+    this.classDistanceEvaluation = classDistanceEvaluation;
+  }
+
+  /**
+   * Returns a {@link ProblemResolver} for the given exception class.
+   *
+   * <p>This method searches for resolvers whose exception type is assignable from the given class,
+   * selecting the most specific match.
+   *
+   * @param clazz exception class to resolve
+   * @return an {@link Optional} containing the matching resolver, or empty if none found
+   */
+  @Override
+  public Optional<ProblemResolver> findResolver(Class<? extends Exception> clazz) {
+    List<ProblemResolver> candidates = new ArrayList<>();
+    for (Map.Entry<Class<? extends Exception>, ProblemResolver> entry : resolvers.entrySet()) {
+      if (entry.getKey().isAssignableFrom(clazz)) {
+        candidates.add(entry.getValue());
+      }
+    }
+
+    return candidates.stream().min(Comparator.comparingInt(r -> calculateDistance(r, clazz)));
+  }
+
+  private int calculateDistance(ProblemResolver resolver, Class<? extends Exception> clazz) {
+    return classDistanceEvaluation.calculate(clazz, resolver.getExceptionClass());
   }
 }

problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/DefaultProblemResolverStore.java

@@ -24,7 +24,7 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-class AbstractProblemResolverStoreTest {
+class DefaultProblemResolverStoreTest {
 
   private static class MyBaseException extends Exception {}
 
@@ -47,7 +47,7 @@ void setUp() {
     ProblemResolver baseResolver = new TestResolver(MyBaseException.class);
     ProblemResolver subResolver = new TestResolver(MySubException.class);
     ProblemResolver otherResolver = new TestResolver(OtherException.class);
-    store = new AbstractProblemResolverStore(List.of(baseResolver, subResolver, otherResolver)) {};
+    store = new DefaultProblemResolverStore(List.of(baseResolver, subResolver, otherResolver));
   }
 
   @Test