/*
 * 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
 *
 *      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 org.apache.juneau.annotation;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

import java.lang.annotation.*;

import org.apache.juneau.*;

/**
 * Annotation that can be applied to classes to control how they are marshalled.
 *
 * <p>
 * Can be used in the following locations:
 * <ul>
 *    <li>Marshalled classes.
 *    <li><ja>@Rest</ja>-annotated classes and <ja>@RestOp</ja>-annotated methods when an {@link #on()} value is specified.
 * </ul>
 *
 * <p>
 * This annotation is typically only applied to non-bean classes.  The {@link Bean @Bean} annotation contains equivalent
 * functionality for bean classes.
 *
 */
@Documented
@Target({ METHOD, TYPE })
@Retention(RUNTIME)
@Inherited
@Repeatable(MarshalledAnnotation.Array.class)
@ContextApply(MarshalledAnnotation.Applier.class)
public @interface Marshalled {

   /**
    * Optional description for the exposed API.
    *
    * @return The annotation value.
    * @since 9.2.0
    */
   String[] description() default {};

   /**
    * POJO example.
    *
    * <p>
    * Specifies an example of the specified class in Simplified JSON format.
    *
    * <p>
    * Examples are used in cases such as POJO examples in Swagger documents.
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    <ja>@Marshalled</ja>(example=<js>"{foo:'bar'}"</js>)
    *    <jk>public class</jk> MyClass {...}
    * </p>
    *
    * <h5 class='section'>Notes:</h5><ul>
    *    <li class='note'>
    *       Setting applies to specified class and all subclasses.
    *    <li class='note'>
    *       Keys are the class of the example.
    *       <br>Values are JSON 5 representation of that class.
    *    <li class='note'>
    *       POJO examples can also be defined on classes via the following:
    *       <ul class='spaced-list'>
    *          <li>A static field annotated with {@link Example @Example}.
    *          <li>A static method annotated with {@link Example @Example} with zero arguments or one {@link BeanSession} argument.
    *          <li>A static method with name <c>example</c> with no arguments or one {@link BeanSession} argument.
    *       </ul>
    *    <li class='note'>
    *       Supports <a class="doclink" href="https://juneau.apache.org/docs/topics/DefaultVarResolver">VarResolver.DEFAULT</a> (e.g. <js>"$C{myConfigVar}"</js>).
    * </ul>
    *
    * <h5 class='section'>See Also:</h5><ul>
    *    <li class='ja'>{@link Example}
    * </ul>
    *
    * @return The annotation value.
    */
   String example() default "";

   /**
    * Implementation class.
    *
    * <p>
    * For interfaces and abstract classes this method can be used to specify an implementation class for the
    * interface/abstract class so that instances of the implementation class are used when instantiated (e.g. during a
    * parse).
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    <ja>@Marshalled</ja>(implClass=MyInterfaceImpl.<jk>class</jk>)
    *    <jk>public class</jk> MyInterface {...}
    * <p>
    *
    * @return The annotation value.
    */
   Class<?> implClass() default void.class;

   /**
    * Dynamically apply this annotation to the specified classes.
    *
    * <p>
    * Used in conjunction with {@link org.apache.juneau.BeanContext.Builder#applyAnnotations(Class...)} to dynamically apply an annotation to an existing class.
    * It is ignored when the annotation is applied directly to classes.
    *
    * <p>
    * The following example shows the equivalent methods for applying the {@link Bean @Bean} annotation to REST methods:
    * <p class='bjava'>
    *    <jc>// Class with explicit annotation.</jc>
    *    <ja>@Marshalled</ja>(example=<js>"{foo:'bar'}"</js>)
    *    <jk>public class</jk> A {...}
    *
    *    <jc>// Class with annotation applied via @BeanConfig</jc>
    *    <jk>public class</jk> B {...}
    *
    *    <jc>// Java REST method with @BeanConfig annotation.</jc>
    *    <ja>@RestOp</ja>(...)
    *    <ja>@Marshalled</ja>(on=<js>"B"</js>, example=<js>"{foo:'bar'}"</js>)
    *    <jk>public void</jk> doFoo() {...}
    * </p>
    *
    * <h5 class='section'>Valid patterns:</h5>
    * <ul class='spaced-list'>
    *  <li>Classes:
    *       <ul>
    *          <li>Fully qualified:
    *             <ul>
    *                <li><js>"com.foo.MyClass"</js>
    *             </ul>
    *          <li>Fully qualified inner class:
    *             <ul>
    *                <li><js>"com.foo.MyClass$Inner1$Inner2"</js>
    *             </ul>
    *          <li>Simple:
    *             <ul>
    *                <li><js>"MyClass"</js>
    *             </ul>
    *          <li>Simple inner:
    *             <ul>
    *                <li><js>"MyClass$Inner1$Inner2"</js>
    *                <li><js>"Inner1$Inner2"</js>
    *                <li><js>"Inner2"</js>
    *             </ul>
    *       </ul>
    *    <li>A comma-delimited list of anything on this list.
    * </ul>
    *
    * <h5 class='section'>See Also:</h5><ul>
    *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/DynamicallyAppliedAnnotations">Dynamically Applied Annotations</a>
    * </ul>
    *
    * @return The annotation value.
    */
   String[] on() default {};

   /**
    * Dynamically apply this annotation to the specified classes.
    *
    * <p>
    * Identical to {@link #on()} except allows you to specify class objects instead of a strings.
    *
    * <h5 class='section'>See Also:</h5><ul>
    *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/DynamicallyAppliedAnnotations">Dynamically Applied Annotations</a>
    * </ul>
    *
    * @return The annotation value.
    */
   Class<?>[] onClass() default {};
}