/*
    * Copyright (C) 2011 The Guava Authors
    *
    * Licensed 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
    *
    * http://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 com.google.common.base;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.annotations.GwtIncompatible;
  import com.google.common.collect.ImmutableSet;
  import com.google.common.testing.GcFinalization;
  import com.google.common.testing.NullPointerTester;
  import com.google.common.testing.SerializableTester;
  
  import junit.framework.TestCase;
  
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.ref.WeakReference;
  import java.lang.reflect.Field;
  import java.net.URLClassLoader;
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * Tests for {@link Enums}.
   *
   * @author Steve McKay
   */
  @GwtCompatible(emulated = true)
  public class EnumsTest extends TestCase {
  
    private enum TestEnum {
      CHEETO,
      HONDA,
      POODLE,
    }
  
    private enum OtherEnum {}
  
    public void testGetIfPresent() {
      assertEquals(Optional.of(TestEnum.CHEETO), Enums.getIfPresent(TestEnum.class, "CHEETO"));
      assertEquals(Optional.of(TestEnum.HONDA), Enums.getIfPresent(TestEnum.class, "HONDA"));
      assertEquals(Optional.of(TestEnum.POODLE), Enums.getIfPresent(TestEnum.class, "POODLE"));
  
      assertTrue(Enums.getIfPresent(TestEnum.class, "CHEETO").isPresent());
      assertTrue(Enums.getIfPresent(TestEnum.class, "HONDA").isPresent());
      assertTrue(Enums.getIfPresent(TestEnum.class, "POODLE").isPresent());
  
      assertEquals(TestEnum.CHEETO, Enums.getIfPresent(TestEnum.class, "CHEETO").get());
      assertEquals(TestEnum.HONDA, Enums.getIfPresent(TestEnum.class, "HONDA").get());
      assertEquals(TestEnum.POODLE, Enums.getIfPresent(TestEnum.class, "POODLE").get());
    }
  
    public void testGetIfPresent_caseSensitive() {
      assertFalse(Enums.getIfPresent(TestEnum.class, "cHEETO").isPresent());
      assertFalse(Enums.getIfPresent(TestEnum.class, "Honda").isPresent());
      assertFalse(Enums.getIfPresent(TestEnum.class, "poodlE").isPresent());
    }
  
    public void testGetIfPresent_whenNoMatchingConstant() {
      assertEquals(Optional.absent(), Enums.getIfPresent(TestEnum.class, "WOMBAT"));
    }
  
    @GwtIncompatible("weak references")
    public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
      WeakReference<?> shadowLoaderReference = doTestClassUnloading();
      GcFinalization.awaitClear(shadowLoaderReference);
    }
  
    // Create a second ClassLoader and use it to get a second version of the TestEnum class.
    // Run Enums.getIfPresent on that other TestEnum and then return a WeakReference containing the
    // new ClassLoader. If Enums.getIfPresent does caching that prevents the shadow TestEnum
    // (and therefore its ClassLoader) from being unloaded, then this WeakReference will never be
    // cleared.
    @GwtIncompatible("weak references")
    private WeakReference<?> doTestClassUnloading() throws Exception {
      URLClassLoader myLoader = (URLClassLoader) getClass().getClassLoader();
      URLClassLoader shadowLoader = new URLClassLoader(myLoader.getURLs(), null);
      @SuppressWarnings("unchecked")
      Class<TestEnum> shadowTestEnum =
          (Class<TestEnum>) Class.forName(TestEnum.class.getName(), false, shadowLoader);
      assertNotSame(shadowTestEnum, TestEnum.class);
      Set<TestEnum> shadowConstants = new HashSet<TestEnum>();
      for (TestEnum constant : TestEnum.values()) {
        Optional<TestEnum> result = Enums.getIfPresent(shadowTestEnum, constant.name());
        assertTrue(result.isPresent());
        shadowConstants.add(result.get());
     }
     assertEquals(ImmutableSet.copyOf(shadowTestEnum.getEnumConstants()), shadowConstants);
     Optional<TestEnum> result = Enums.getIfPresent(shadowTestEnum, "blibby");
     assertFalse(result.isPresent());
     return new WeakReference<ClassLoader>(shadowLoader);
   }
 
   public void testStringConverter_convert() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals(TestEnum.CHEETO, converter.convert("CHEETO"));
     assertEquals(TestEnum.HONDA, converter.convert("HONDA"));
     assertEquals(TestEnum.POODLE, converter.convert("POODLE"));
     assertNull(converter.convert(null));
     assertNull(converter.reverse().convert(null));
   }
 
   public void testStringConverter_convertError() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     try {
       converter.convert("xxx");
       fail();
     } catch (IllegalArgumentException expected) {
     }
   }
 
   public void testStringConverter_reverse() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertEquals("CHEETO", converter.reverse().convert(TestEnum.CHEETO));
     assertEquals("HONDA", converter.reverse().convert(TestEnum.HONDA));
     assertEquals("POODLE", converter.reverse().convert(TestEnum.POODLE));
   }
 
   @GwtIncompatible("NullPointerTester")
   public void testStringConverter_nullPointerTester() throws Exception {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicInstanceMethods(converter);
   }
 
   public void testStringConverter_nullConversions() {
     Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
     assertNull(converter.convert(null));
     assertNull(converter.reverse().convert(null));
   }
 
   @GwtIncompatible("Class.getName()")
   public void testStringConverter_toString() {
     assertEquals(
         "Enums.stringConverter(com.google.common.base.EnumsTest$TestEnum.class)",
         Enums.stringConverter(TestEnum.class).toString());
   }
 
   public void testStringConverter_serialization() {
     SerializableTester.reserializeAndAssert(Enums.stringConverter(TestEnum.class));
   }
 
   @GwtIncompatible("NullPointerTester")
   public void testNullPointerExceptions() {
     NullPointerTester tester = new NullPointerTester();
     tester.testAllPublicStaticMethods(Enums.class);
   }
 
   @Retention(RetentionPolicy.RUNTIME)
   private @interface ExampleAnnotation {}
 
   private enum AnEnum {
     @ExampleAnnotation FOO,
     BAR
   }
 
   @GwtIncompatible("reflection")
   public void testGetField() {
     Field foo = Enums.getField(AnEnum.FOO);
     assertEquals("FOO", foo.getName());
     assertTrue(foo.isAnnotationPresent(ExampleAnnotation.class));
 
     Field bar = Enums.getField(AnEnum.BAR);
     assertEquals("BAR", bar.getName());
     assertFalse(bar.isAnnotationPresent(ExampleAnnotation.class));
   }
 }