/*
 * Copyright 2002-2020 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.servlet.config.annotation;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.springframework.context.ApplicationContext;
import org.springframework.http.HttpStatus;
import org.springframework.lang.Nullable;
import org.springframework.util.AntPathMatcher;
import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
import org.springframework.web.util.pattern.PathPattern;

Assists with the registration of simple automated controllers pre-configured
with status code and/or a view.
Author:
Rossen Stoyanchev, Keith Donald
Since:
3.1/**
 * Assists with the registration of simple automated controllers pre-configured
 * with status code and/or a view.
 *
 * @author Rossen Stoyanchev
 * @author Keith Donald
 * @since 3.1
 */
public class ViewControllerRegistry {

	@Nullable
	private ApplicationContext applicationContext;

	private final List<ViewControllerRegistration> registrations = new ArrayList<>(4);

	private final List<RedirectViewControllerRegistration> redirectRegistrations = new ArrayList<>(10);

	private int order = 1;


	
Class constructor with ApplicationContext. 
Since:
4.3.12/**
	 * Class constructor with {@link ApplicationContext}.
	 * @since 4.3.12
	 */
	public ViewControllerRegistry(@Nullable ApplicationContext applicationContext) {
		this.applicationContext = applicationContext;
	}


	
Map a URL path or pattern to a view controller to render a response with
the configured status code and view.
Patterns such as "/admin/**" or "/articles/{articlename:\\w+}" are supported. For pattern syntax see PathPattern when parsed patterns are enabled or AntPathMatcher otherwise. The syntax is largely the same with PathPattern more tailored for web usage and more efficient. 
Note: If an @RequestMapping method is mapped to a URL for any HTTP method then a view controller cannot handle the same URL. For this reason it is recommended to avoid splitting URL handling across an annotated controller and a view controller. /**
	 * Map a URL path or pattern to a view controller to render a response with
	 * the configured status code and view.
	 * <p>Patterns such as {@code "/admin/**"} or {@code "/articles/{articlename:\\w+}"}
	 * are supported. For pattern syntax see {@link PathPattern} when parsed
	 * patterns are {@link PathMatchConfigurer#setPatternParser enabled} or
	 * {@link AntPathMatcher} otherwise. The syntax is largely the same with
	 * {@link PathPattern} more tailored for web usage and more efficient.
	 * <p><strong>Note:</strong> If an {@code @RequestMapping} method is mapped
	 * to a URL for any HTTP method then a view controller cannot handle the
	 * same URL. For this reason it is recommended to avoid splitting URL
	 * handling across an annotated controller and a view controller.
	 */
	public ViewControllerRegistration addViewController(String urlPathOrPattern) {
		ViewControllerRegistration registration = new ViewControllerRegistration(urlPathOrPattern);
		registration.setApplicationContext(this.applicationContext);
		this.registrations.add(registration);
		return registration;
	}

	
Map a view controller to the given URL path or pattern in order to redirect
to another URL.
For pattern syntax see PathPattern when parsed patterns are enabled or AntPathMatcher otherwise. The syntax is largely the same with PathPattern more tailored for web usage and more efficient. 
By default the redirect URL is expected to be relative to the current
ServletContext, i.e. as relative to the web application root.
Since:
4.1/**
	 * Map a view controller to the given URL path or pattern in order to redirect
	 * to another URL.
	 * <p>For pattern syntax see {@link PathPattern} when parsed patterns
	 * are {@link PathMatchConfigurer#setPatternParser enabled} or
	 * {@link AntPathMatcher} otherwise. The syntax is largely the same with
	 * {@link PathPattern} more tailored for web usage and more efficient.
	 * <p>By default the redirect URL is expected to be relative to the current
	 * ServletContext, i.e. as relative to the web application root.
	 * @since 4.1
	 */
	public RedirectViewControllerRegistration addRedirectViewController(String urlPath, String redirectUrl) {
		RedirectViewControllerRegistration registration = new RedirectViewControllerRegistration(urlPath, redirectUrl);
		registration.setApplicationContext(this.applicationContext);
		this.redirectRegistrations.add(registration);
		return registration;
	}

	
Map a simple controller to the given URL path (or pattern) in order to
set the response status to the given code without rendering a body.
For pattern syntax see PathPattern when parsed patterns are enabled or AntPathMatcher otherwise. The syntax is largely the same with PathPattern more tailored for web usage and more efficient. 
Since:
4.1/**
	 * Map a simple controller to the given URL path (or pattern) in order to
	 * set the response status to the given code without rendering a body.
	 * <p>For pattern syntax see {@link PathPattern} when parsed patterns
	 * are {@link PathMatchConfigurer#setPatternParser enabled} or
	 * {@link AntPathMatcher} otherwise. The syntax is largely the same with
	 * {@link PathPattern} more tailored for web usage and more efficient.
	 * @since 4.1
	 */
	public void addStatusController(String urlPath, HttpStatus statusCode) {
		ViewControllerRegistration registration = new ViewControllerRegistration(urlPath);
		registration.setApplicationContext(this.applicationContext);
		registration.setStatusCode(statusCode);
		registration.getViewController().setStatusOnly(true);
		this.registrations.add(registration);
	}

	
Specify the order to use for the HandlerMapping used to map view controllers relative to other handler mappings configured in Spring MVC. 
By default this is set to 1, i.e. right after annotated controllers,
which are ordered at 0.
/**
	 * Specify the order to use for the {@code HandlerMapping} used to map view
	 * controllers relative to other handler mappings configured in Spring MVC.
	 * <p>By default this is set to 1, i.e. right after annotated controllers,
	 * which are ordered at 0.
	 */
	public void setOrder(int order) {
		this.order = order;
	}


	
Return the HandlerMapping that contains the registered view controller mappings, or null for no registrations. 
Since:
4.3.12/**
	 * Return the {@code HandlerMapping} that contains the registered view
	 * controller mappings, or {@code null} for no registrations.
	 * @since 4.3.12
	 */
	@Nullable
	protected SimpleUrlHandlerMapping buildHandlerMapping() {
		if (this.registrations.isEmpty() && this.redirectRegistrations.isEmpty()) {
			return null;
		}

		Map<String, Object> urlMap = new LinkedHashMap<>();
		for (ViewControllerRegistration registration : this.registrations) {
			urlMap.put(registration.getUrlPath(), registration.getViewController());
		}
		for (RedirectViewControllerRegistration registration : this.redirectRegistrations) {
			urlMap.put(registration.getUrlPath(), registration.getViewController());
		}

		return new SimpleUrlHandlerMapping(urlMap, this.order);
	}

}