package com.ruoyi.gateway.config;

import org.springframework.beans.factory.annotation.Autowired;
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.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
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 com.ruoyi.gateway.handler.ValidateCodeHandler;
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 ruoyi
 */
@Configuration
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, Content-Type, Authorization, credential, X-XSRF-TOKEN, token, username, client, request-origin, sign, nonce_str, timestamp, X-Login-Session";
	private static final String ALLOWED_METHODS = "GET,POST,PUT,DELETE,OPTIONS,HEAD";
	private static final String ALLOWED_EXPOSE = "*";
	private static final String MAX_AGE = "18000";

	@Autowired
	private ValidateCodeHandler validateCodeHandler;

	@SuppressWarnings("rawtypes")
	@Bean
	public RouterFunction routerFunction() {
		return RouterFunctions.route(
				RequestPredicates.GET("/code"),
				validateCodeHandler);
	}

	/**
	 * 跨域配置
	 */
	@Bean
	public WebFilter corsFilter() {
		return (ServerWebExchange ctx, WebFilterChain chain) -> {
			ServerHttpRequest request = ctx.getRequest();
			if (CorsUtils.isCorsRequest(request)) {
				ServerHttpResponse response = ctx.getResponse();
				// 所有跨域响应（含预检 OPTIONS）统一在提交前设置 CORS 头
				response.beforeCommit(() -> {
					applyCorsHeaders(request, response);
					return Mono.empty();
				});
				if (request.getMethod() == HttpMethod.OPTIONS) {
					response.setStatusCode(HttpStatus.OK);
					return Mono.empty();
				}
			}
			return chain.filter(ctx);
		};
	}

	private void applyCorsHeaders(ServerHttpRequest request, ServerHttpResponse response) {
		HttpHeaders headers = response.getHeaders();
		String origin = request.getHeaders().getOrigin();
		headers.set("Access-Control-Allow-Headers", ALLOWED_HEADERS);
		headers.set("Access-Control-Allow-Methods", ALLOWED_METHODS);
		headers.set("Access-Control-Expose-Headers", ALLOWED_EXPOSE);
		headers.set("Access-Control-Max-Age", MAX_AGE);
		if (origin != null) {
			// 反射请求来源，支持携带凭据（Allow-Origin 为 * 时浏览器会拒绝 Allow-Credentials）
			headers.set("Access-Control-Allow-Origin", origin);
			headers.set("Access-Control-Allow-Credentials", "true");
			headers.set(HttpHeaders.VARY, HttpHeaders.ORIGIN);
		}
		else {
			headers.set("Access-Control-Allow-Origin", "*");
		}
	}
}