/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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 libcore.java.lang.reflect;

import java.lang.annotation.Annotation;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import junit.framework.TestCase;

public final class AnnotationsTest extends TestCase {

    public void testClassDirectAnnotations() {
        assertAnnotatedElement(Type.class, AnnotationA.class, AnnotationB.class);
    }

    public void testClassInheritedAnnotations() {
        assertAnnotatedElement(ExtendsType.class, AnnotationB.class);
    }

    public void testConstructorAnnotations() throws Exception {
        Constructor<Type> constructor = Type.class.getConstructor();
        assertAnnotatedElement(constructor, AnnotationA.class, AnnotationC.class);
    }

    public void testFieldAnnotations() throws Exception {
        Field field = Type.class.getField("field");
        assertAnnotatedElement(field, AnnotationA.class, AnnotationD.class);
    }

    public void testMethodAnnotations() throws Exception {
        Method method = Type.class.getMethod("method", String.class, String.class);
        assertAnnotatedElement(method, AnnotationB.class, AnnotationC.class);
    }

    public void testParameterAnnotations() throws Exception {
        Method method = Type.class.getMethod("method", String.class, String.class);
        Annotation[][] parameterAnnotations = method.getParameterAnnotations();
        assertEquals(2, parameterAnnotations.length);
        assertEquals(set(AnnotationB.class, AnnotationD.class),
                annotationsToTypes(parameterAnnotations[0]));
        assertEquals(set(AnnotationC.class, AnnotationD.class),
                annotationsToTypes(parameterAnnotations[1]));
    }

    @Retention(RetentionPolicy.RUNTIME)
    public @interface AnnotationA {}

    @Inherited
    @Retention(RetentionPolicy.RUNTIME)
    public @interface AnnotationB {}

    @Retention(RetentionPolicy.RUNTIME)
    public @interface AnnotationC {}

    @Retention(RetentionPolicy.RUNTIME)
    public @interface AnnotationD {}

    @AnnotationA @AnnotationB
    public static class Type {
        @AnnotationA @AnnotationC public Type() {}
        @AnnotationA @AnnotationD public String field;
        @AnnotationB @AnnotationC public void method(@AnnotationB @AnnotationD String parameter1,
                @AnnotationC @AnnotationD String parameter2) {}
    }

    public static class ExtendsType extends Type {}


    private void assertAnnotatedElement(
            AnnotatedElement element, Class<? extends Annotation>... expectedAnnotations) {
        Set<Class<? extends Annotation>> actualTypes = annotationsToTypes(element.getAnnotations());
        Set<Class<? extends Annotation>> expectedTypes = set(expectedAnnotations);
        assertEquals(expectedTypes, actualTypes);

        // getAnnotations() should be consistent with isAnnotationPresent() and getAnnotation()
        assertPresent(expectedTypes.contains(AnnotationA.class), element, AnnotationA.class);
        assertPresent(expectedTypes.contains(AnnotationB.class), element, AnnotationB.class);
        assertPresent(expectedTypes.contains(AnnotationC.class), element, AnnotationC.class);

        try {
            element.isAnnotationPresent(null);
            fail();
        } catch (NullPointerException expected) {
        }

        try {
            element.getAnnotation(null);
            fail();
        } catch (NullPointerException expected) {
        }
    }

    private Set<Class<? extends Annotation>> annotationsToTypes(Annotation[] annotations) {
        Set<Class<? extends Annotation>> result = new HashSet<Class<? extends Annotation>>();
        for (Annotation annotation : annotations) {
            result.add(annotation.annotationType());
        }
        return result;
    }

    private void assertPresent(boolean present, AnnotatedElement element,
            Class<? extends Annotation> annotation) {
        if (present) {
            assertNotNull(element.getAnnotation(annotation));
            assertTrue(element.isAnnotationPresent(annotation));
        } else {
            assertNull(element.getAnnotation(annotation));
            assertFalse(element.isAnnotationPresent(annotation));
        }
    }

    private <T> Set<T> set(T... instances) {
        return new HashSet<T>(Arrays.asList(instances));
    }
}