feat: add UnnecessaryModifier rule (#219)

code-transformation/src/main/java/xyz/keksdose/spoon/code_solver/analyzer/qodana/QodanaRules.java

@@ -13,6 +13,7 @@
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.SizeReplaceableByIsEmpty;
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnnecessaryInterfaceModifier;
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnnecessaryLocalVariable;
+import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnnecessaryModifier;
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnnecessaryReturn;
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnnecessaryToStringCall;
 import xyz.keksdose.spoon.code_solver.analyzer.qodana.rules.UnusedImport;
@@ -33,7 +34,9 @@ public enum QodanaRules implements AnalyzerRule {
     UNNECESSARY_TO_STRING_CALL("UnnecessaryToStringCall", UnnecessaryToStringCall::new),
     UNUSED_IMPORT("UnusedImport", UnusedImport::new),
     PROTECTED_MEMBER_IN_FINAL_CLASS("ProtectedMemberInFinalClass", ProtectedMemberInFinalClass::new),
+    UNNECESSARY_MODIFIER("UnnecessaryModifier", UnnecessaryModifier::new),
     POINTLESS_BOOLEAN_EXPRESSION("PointlessBooleanExpression", PointlessBooleanExpression::new);
+
     private final String ruleId;
     private final Function<AnalyzerResult, AbstractRefactoring> refactoring;
 

code-transformation/src/main/java/xyz/keksdose/spoon/code_solver/analyzer/qodana/rules/UnnecessaryModifier.java

@@ -0,0 +1,66 @@
+package xyz.keksdose.spoon.code_solver.analyzer.qodana.rules;
+
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.List;
+import spoon.reflect.declaration.CtElement;
+import spoon.reflect.declaration.CtModifiable;
+import spoon.reflect.declaration.CtType;
+import xyz.keksdose.spoon.code_solver.analyzer.PositionScanner;
+import xyz.keksdose.spoon.code_solver.api.analyzer.AnalyzerResult;
+import xyz.keksdose.spoon.code_solver.history.Change;
+import xyz.keksdose.spoon.code_solver.history.ChangeListener;
+import xyz.keksdose.spoon.code_solver.history.MarkdownString;
+import xyz.keksdose.spoon.code_solver.transformations.BadSmell;
+
+public class UnnecessaryModifier extends AbstractRefactoring {
+
+    public UnnecessaryModifier(AnalyzerResult result) {
+        super(result);
+    }
+
+    private static final BadSmell UNNECESSARY_MODIFIER = new BadSmell() {
+        @Override
+        public MarkdownString getName() {
+            return MarkdownString.fromRaw("Unnecessary-Modifier");
+        }
+
+        @Override
+        public MarkdownString getDescription() {
+            return MarkdownString.fromRaw(
+                    "Some modifiers are not needed, because they are already the default and implicit. These modifiers can be removed.");
+        }
+    };
+
+    @Override
+    public void refactor(ChangeListener listener, CtType<?> type) {
+        if (type.isAnonymous() || !isSameType(type, Path.of(result.filePath()))) {
+            return;
+        }
+        String modifier = result.messageMarkdown().split("`")[1];
+        if (modifier == null || modifier.isEmpty()) {
+            return;
+        }
+        for (CtElement match : PositionScanner.findLineOnly(type, result.position())) {
+            if (match instanceof CtModifiable ctModifierHandler) {
+                var modifiers = new HashSet<>(ctModifierHandler.getModifiers());
+                modifiers.removeIf(v -> v.toString().equals(modifier.toLowerCase()));
+                ctModifierHandler.setModifiers(modifiers);
+                listener.setChanged(
+                        type.getTopLevelType(),
+                        new Change(
+                                UNNECESSARY_MODIFIER,
+                                MarkdownString.fromMarkdown(
+                                        "Unnecessary modifier " + modifier + " removed",
+                                        "Unnecessary modifier `" + modifier + "` removed"),
+                                type.getTopLevelType(),
+                                result));
+            }
+        }
+    }
+
+    @Override
+    public List<BadSmell> getHandledBadSmells() {
+        return List.of(UNNECESSARY_MODIFIER);
+    }
+}