/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.commons.lang3;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assumptions.assumeTrue;
  
  import java.io.IOException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.Map;
  
  import javax.tools.JavaCompiler;
  import javax.tools.ToolProvider;
  
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.io.TempDir;
  
  /**
   * {@link ClassUtils#getShortClassName(Class)} can throw {@link NoClassDefFoundError} when the supplied class is an inner class whose enclosing (outer) class
   * has been removed from the classpath.
   *
   * <p>
   * The code path lives in the {@code while (x != null)} loop of {@code getShortClassName(Class)}: it calls {@code x.getSimpleName()} and
   * {@code x.getDeclaringClass()}. Both of those JDK methods resolve the {@code InnerClasses} attribute of the inner class' bytecode, and when the enclosing
   * class is missing the JVM throws {@link NoClassDefFoundError} from inside {@code Class#getDeclaringClass0}/{@code getSimpleBinaryName}.
   * </p>
   * <p>
   * The test compiles two classes ({@code F030Outer} and {@code F030Outer$Inner}) with the in-process {@code javax.tools.JavaCompiler}, deletes the outer class
   * file, loads the inner class via a fresh {@link URLClassLoader}, and then invokes {@link ClassUtils#getShortClassName(Class)}.
   * </p>
   *
   * <p>
   * At baseline (commit {@code 8538458e7}) the call propagates {@link NoClassDefFoundError}. After the fix the {@code if/else} block around
   * {@code isAnonymousClass}/{@code isLocalClass} is wrapped in a {@code try / catch (NoClassDefFoundError)} that falls back to
   * {@link ClassUtils#getShortClassName(String)} on the binary name.
   * </p>
   */
  public class ClassUtilsGetShortClassNameTest {
  
      // @formatter:off
      private static final String OUTER_SRC = ""
          + "package f030;\n"
          + "public class F030Outer {\n"
          + "    public static class Inner {\n"
          + "        public int value;\n"
          + "    }\n"
          + "}\n";
      // @formatter:on
  
      /**
       * Compiles {@code f030.F030Outer} (and its nested {@code Inner}) into the supplied directory using the in-process Java compiler.
       *
       * @return {@code true} on success, {@code false} if the compiler is not available (running on a JRE rather than a JDK).
       */
      private static boolean compileOuterWithInner(final Path classesDir) throws IOException {
          final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
          assertNotNull("JDK compiler missing");
          final Path srcDir = classesDir.resolve("..").resolve("src").normalize();
          Files.createDirectories(srcDir);
          final Path outerJava = srcDir.resolve("F030Outer.java");
          Files.write(outerJava, OUTER_SRC.getBytes(StandardCharsets.UTF_8));
          Files.createDirectories(classesDir);
          return compiler.run(null, null, null, "-d", classesDir.toString(), outerJava.toString()) == 0;
      }
  
      /**
       * Creates a child {@link URLClassLoader} that can resolve only the inner class file, the outer class file is deliberately omitted from the directory it
       * points at, simulating a torn deployment / shaded JAR.
       */
      private static URLClassLoader innerOnlyLoader(final Path innerOnlyDir) throws IOException {
          final URL url = innerOnlyDir.toUri().toURL();
          return new URLClassLoader(new URL[] { url }, ClassLoader.getSystemClassLoader().getParent());
      }
  
      /**
       * Anonymous and local classes follow a separate code path that calls {@code getShortClassName(c.getName())} directly. The compiler-generated ordinal (for
       * example, {@code $1}) is preserved by the legacy contract, so the short name ends with {@code ".<digits>"}.
      */
     @Test
     public void testAnonymousAndLocalClassesUseSeparatePath() {
         final Runnable anon = new Runnable() {
 
             @Override
             public void run() {
                 /* no-op */
             }
         };
         final String shortName = ClassUtils.getShortClassName(anon.getClass());
         assertNotNull(shortName);
         assertTrue(shortName.matches(".*\\.[0-9].*"), "Anonymous class short name should preserve the compiler ordinal: " + shortName);
     }
 
     @Test
     public void testGetShortClassNameDoesNotThrowOnNormalClasses() {
         assertEquals("String", ClassUtils.getShortClassName(String.class));
         assertEquals("Map.Entry", ClassUtils.getShortClassName(Map.Entry.class));
         assertEquals("int[]", ClassUtils.getShortClassName(int[].class));
     }
 
     @Test
     public void testGetShortClassNameOnInnerClassWithMissingOuter(@TempDir final Path tempDir) throws Exception {
         final Path classesDir = tempDir.resolve("classes");
         assumeTrue(compileOuterWithInner(classesDir));
         final Path outerClass = classesDir.resolve("f030").resolve("F030Outer.class");
         final Path innerClass = classesDir.resolve("f030").resolve("F030Outer$Inner.class");
         assumeTrue(Files.exists(outerClass) && Files.exists(innerClass), "Expected compiled class files to exist");
         final Path innerOnly = tempDir.resolve("inner-only");
         Files.createDirectories(innerOnly.resolve("f030"));
         Files.copy(innerClass, innerOnly.resolve("f030").resolve("F030Outer$Inner.class"));
         try (URLClassLoader cl = innerOnlyLoader(innerOnly)) {
             final Class<?> inner = Class.forName("f030.F030Outer$Inner", false, cl);
             assertEquals("f030.F030Outer$Inner", inner.getName());
             // Sanity: at the JDK layer, both getSimpleName and getDeclaringClass
             // throw NoClassDefFoundError for this inner class on the current JVM.
             assertThrows(NoClassDefFoundError.class, inner::getSimpleName);
             assertThrows(NoClassDefFoundError.class, inner::getDeclaringClass);
             // Post-fix: ClassUtils.getShortClassName(Class) catches NoClassDefFoundError
             // thrown anywhere inside the if (isAnonymous || isLocal){...} else {...} block
             // and falls back to string-parsing the binary name "f030.F030Outer$Inner"
             // which yields "F030Outer.Inner" (per the documented contract of
             // getShortClassName(String): the '$' separator is replaced with '.').
             assertEquals("F030Outer.Inner", ClassUtils.getShortClassName(inner));
         }
     }
 
     @Test
     public void testGetShortClassNameReturnsNonNullForStandardClasses() {
         assertNotNull(ClassUtils.getShortClassName(String.class));
         assertNotNull(ClassUtils.getShortClassName(Integer.class));
     }
 }