/*
 *      Copyright (c) 2018-2028, Chill Zhuang All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice,
 *  this list of conditions and the following disclaimer.
 *  Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in the
 *  documentation and/or other materials provided with the distribution.
 *  Neither the name of the dreamlu.net developer nor the names of its
 *  contributors may be used to endorse or promote products derived from
 *  this software without specific prior written permission.
 *  Author: Chill 庄骞 (smallchill@163.com)
 */

package org.springblade.gateway.config;

import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springblade.gateway.handler.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
import org.springframework.web.filter.reactive.HiddenHttpMethodFilter;
import org.springframework.web.reactive.function.server.RequestPredicates;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.RouterFunctions;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

/**
 * 路由配置信息
 *
 * @author Chill
 */
@Slf4j
@Configuration
@AllArgsConstructor
public class RouterFunctionConfiguration {

	/**
	 * 这里为支持的请求头，如果有自定义的header字段请自己添加
	 */
	private static final String ALLOWED_HEADERS = "x-requested-with, blade-auth, Content-Type, Authorization, credential, X-XSRF-TOKEN, token, username, client";
	private static final String ALLOWED_METHODS = "*";
	private static final String ALLOWED_ORIGIN = "*";
	private static final String ALLOWED_EXPOSE = "*";
	private static final String MAX_AGE = "18000L";

	private final HystrixFallbackHandler hystrixFallbackHandler;
	private final SwaggerResourceHandler swaggerResourceHandler;
	private final SwaggerSecurityHandler swaggerSecurityHandler;
	private final SwaggerUiHandler swaggerUiHandler;

	@Bean
	public WebFilter corsFilter() {
		return (ServerWebExchange ctx, WebFilterChain chain) -> {
			ServerHttpRequest request = ctx.getRequest();
			if (CorsUtils.isCorsRequest(request)) {
				ServerHttpResponse response = ctx.getResponse();
				HttpHeaders headers = response.getHeaders();
				headers.add("Access-Control-Allow-Headers", ALLOWED_HEADERS);
				headers.add("Access-Control-Allow-Methods", ALLOWED_METHODS);
				headers.add("Access-Control-Allow-Origin", ALLOWED_ORIGIN);
				headers.add("Access-Control-Expose-Headers", ALLOWED_EXPOSE);
				headers.add("Access-Control-Max-Age", MAX_AGE);
				headers.add("Access-Control-Allow-Credentials", "true");
				if (request.getMethod() == HttpMethod.OPTIONS) {
					response.setStatusCode(HttpStatus.OK);
					return Mono.empty();
				}
			}
			return chain.filter(ctx);
		};
	}

	@Bean
	public RouterFunction routerFunction() {
		return RouterFunctions.route(
			RequestPredicates.path("/fallback")
				.and(RequestPredicates.accept(MediaType.TEXT_PLAIN)), hystrixFallbackHandler)
			.andRoute(RequestPredicates.GET("/swagger-resources")
				.and(RequestPredicates.accept(MediaType.ALL)), swaggerResourceHandler)
			.andRoute(RequestPredicates.GET("/swagger-resources/configuration/ui")
				.and(RequestPredicates.accept(MediaType.ALL)), swaggerUiHandler)
			.andRoute(RequestPredicates.GET("/swagger-resources/configuration/security")
				.and(RequestPredicates.accept(MediaType.ALL)), swaggerSecurityHandler);

	}

	/**
	 * 解决springboot2.0.5版本出现的 Only one connection receive subscriber allowed.
	 * 参考：https://github.com/spring-cloud/spring-cloud-gateway/issues/541
	 */
	@Bean
	public HiddenHttpMethodFilter hiddenHttpMethodFilter() {
		return new HiddenHttpMethodFilter() {
			@Override
			public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
				return chain.filter(exchange);
			}
		};
	}

}