/*
 * Copyright 2002-2018 the original author or 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
 *
 *      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.springframework.web.bind.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.core.annotation.AliasFor;

/**
 * Annotation for mapping web requests onto methods in request-handling classes
 * with flexible method signatures.
 *
 * <p>Both Spring MVC and Spring WebFlux support this annotation through a
 * {@code RequestMappingHandlerMapping} and {@code RequestMappingHandlerAdapter}
 * in their respective modules and package structure. For the exact list of
 * supported handler method arguments and return types in each, please use the
 * reference documentation links below:
 * <ul>
 * <li>Spring MVC
 * <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-arguments">Method Arguments</a>
 * and
 * <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-return-types">Return Values</a>
 * </li>
 * <li>Spring WebFlux
 * <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-ann-arguments">Method Arguments</a>
 * and
 * <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-ann-return-types">Return Values</a>
 * </li>
 * </ul>
 *
 * <p><strong>Note:</strong> This annotation can be used both at the class and
 * at the method level. In most cases, at the method level applications will
 * prefer to use one of the HTTP method specific variants
 * {@link GetMapping @GetMapping}, {@link PostMapping @PostMapping},
 * {@link PutMapping @PutMapping}, {@link DeleteMapping @DeleteMapping}, or
 * {@link PatchMapping @PatchMapping}.</p>
 *
 * <p><b>NOTE:</b> When using controller interfaces (e.g. for AOP proxying),
 * make sure to consistently put <i>all</i> your mapping annotations - such as
 * {@code @RequestMapping} and {@code @SessionAttributes} - on
 * the controller <i>interface</i> rather than on the implementation class.
 *
 * @author Juergen Hoeller
 * @author Arjen Poutsma
 * @author Sam Brannen
 * @since 2.5
 * @see GetMapping
 * @see PostMapping
 * @see PutMapping
 * @see DeleteMapping
 * @see PatchMapping
 * @see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter
 * @see org.springframework.web.reactive.result.method.annotation.RequestMappingHandlerAdapter
 */
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Mapping
public @interface RequestMapping {

	/**
	 * Assign a name to this mapping.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used on both levels, a combined name is derived by concatenation
	 * with "#" as separator.
	 * @see org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder
	 * @see org.springframework.web.servlet.handler.HandlerMethodMappingNamingStrategy
	 */
	String name() default "";

	/**
	 * The primary mapping expressed by this annotation.
	 * <p>This is an alias for {@link #path}. For example
	 * {@code @RequestMapping("/foo")} is equivalent to
	 * {@code @RequestMapping(path="/foo")}.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit
	 * this primary mapping, narrowing it for a specific handler method.
	 */
	@AliasFor("path")
	String[] value() default {};

	/**
	 * The path mapping URIs (e.g. "/myPath.do").
	 * Ant-style path patterns are also supported (e.g. "/myPath/*.do").
	 * At the method level, relative paths (e.g. "edit.do") are supported
	 * within the primary mapping expressed at the type level.
	 * Path mapping URIs may contain placeholders (e.g. "/${connect}").
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit
	 * this primary mapping, narrowing it for a specific handler method.
	 * @see org.springframework.web.bind.annotation.ValueConstants#DEFAULT_NONE
	 * @since 4.2
	 */
	@AliasFor("value")
	String[] path() default {};

	/**
	 * The HTTP request methods to map to, narrowing the primary mapping:
	 * GET, POST, HEAD, OPTIONS, PUT, PATCH, DELETE, TRACE.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit
	 * this HTTP method restriction (i.e. the type-level restriction
	 * gets checked before the handler method is even resolved).
	 */
	RequestMethod[] method() default {};

	/**
	 * The parameters of the mapped request, narrowing the primary mapping.
	 * <p>Same format for any environment: a sequence of "myParam=myValue" style
	 * expressions, with a request only mapped if each such parameter is found
	 * to have the given value. Expressions can be negated by using the "!=" operator,
	 * as in "myParam!=myValue". "myParam" style expressions are also supported,
	 * with such parameters having to be present in the request (allowed to have
	 * any value). Finally, "!myParam" style expressions indicate that the
	 * specified parameter is <i>not</i> supposed to be present in the request.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit
	 * this parameter restriction (i.e. the type-level restriction
	 * gets checked before the handler method is even resolved).
	 * <p>Parameter mappings are considered as restrictions that are enforced at
	 * the type level. The primary path mapping (i.e. the specified URI value)
	 * still has to uniquely identify the target handler, with parameter mappings
	 * simply expressing preconditions for invoking the handler.
	 */
	String[] params() default {};

	/**
	 * The headers of the mapped request, narrowing the primary mapping.
	 * <p>Same format for any environment: a sequence of "My-Header=myValue" style
	 * expressions, with a request only mapped if each such header is found
	 * to have the given value. Expressions can be negated by using the "!=" operator,
	 * as in "My-Header!=myValue". "My-Header" style expressions are also supported,
	 * with such headers having to be present in the request (allowed to have
	 * any value). Finally, "!My-Header" style expressions indicate that the
	 * specified header is <i>not</i> supposed to be present in the request.
	 * <p>Also supports media type wildcards (*), for headers such as Accept
	 * and Content-Type. For instance,
	 * <pre class="code">
	 * &#064;RequestMapping(value = "/something", headers = "content-type=text/*")
	 * </pre>
	 * will match requests with a Content-Type of "text/html", "text/plain", etc.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit
	 * this header restriction (i.e. the type-level restriction
	 * gets checked before the handler method is even resolved).
	 * @see org.springframework.http.MediaType
	 */
	String[] headers() default {};

	/**
	 * The consumable media types of the mapped request, narrowing the primary mapping.
	 * <p>The format is a single media type or a sequence of media types,
	 * with a request only mapped if the {@code Content-Type} matches one of these media types.
	 * Examples:
	 * <pre class="code">
	 * consumes = "text/plain"
	 * consumes = {"text/plain", "application/*"}
	 * </pre>
	 * Expressions can be negated by using the "!" operator, as in "!text/plain", which matches
	 * all requests with a {@code Content-Type} other than "text/plain".
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings override
	 * this consumes restriction.
	 * @see org.springframework.http.MediaType
	 * @see javax.servlet.http.HttpServletRequest#getContentType()
	 */
	String[] consumes() default {};

	/**
	 * The producible media types of the mapped request, narrowing the primary mapping.
	 * <p>The format is a single media type or a sequence of media types,
	 * with a request only mapped if the {@code Accept} matches one of these media types.
	 * Examples:
	 * <pre class="code">
	 * produces = "text/plain"
	 * produces = {"text/plain", "application/*"}
	 * produces = MediaType.APPLICATION_JSON_UTF8_VALUE
	 * </pre>
	 * <p>It affects the actual content type written, for example to produce a JSON response
	 * with UTF-8 encoding, {@link org.springframework.http.MediaType#APPLICATION_JSON_UTF8_VALUE} should be used.
	 * <p>Expressions can be negated by using the "!" operator, as in "!text/plain", which matches
	 * all requests with a {@code Accept} other than "text/plain".
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings override
	 * this produces restriction.
	 * @see org.springframework.http.MediaType
	 */
	String[] produces() default {};

}
