package com.github.tangyi.gateway.config;

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.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

import static io.netty.handler.codec.http.cookie.CookieHeaderNames.MAX_AGE;
import static org.springframework.web.cors.CorsConfiguration.ALL;

/**
 * 跨域配置
 *
 * @author tangyi
 * @date 2019/07/06 17:12
 */
@Configuration
public class CorsConfig {

    @Bean
    public WebFilter corsFilter() {
        return (ServerWebExchange ctx, WebFilterChain chain) -> {
            ServerHttpRequest request = ctx.getRequest();
            if (!CorsUtils.isCorsRequest(request))
                return chain.filter(ctx);
            HttpHeaders requestHeaders = request.getHeaders();
            ServerHttpResponse response = ctx.getResponse();
            HttpMethod requestMethod = requestHeaders.getAccessControlRequestMethod();
            HttpHeaders headers = response.getHeaders();
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, requestHeaders.getOrigin());
            headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, requestHeaders.getAccessControlRequestHeaders());
            if (requestMethod != null)
                headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
            headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, ALL);
            headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, MAX_AGE);
            if (request.getMethod() == HttpMethod.OPTIONS) {
                response.setStatusCode(HttpStatus.OK);
                return Mono.empty();
            }
            return chain.filter(ctx);
        };
    }
}
