package com.it.rattan.config;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {

    }

    /**
     * 跨域过滤器 - 支持凭证，最高优先级
     */
    @Bean
    public FilterRegistrationBean<Filter> corsFilterRegistration() {
        FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new CorsFilter());
        registration.addUrlPatterns("/*");
        registration.setName("corsFilter");
        registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registration;
    }

    /**
     * CORS 过滤器实现
     */
    private static class CorsFilter implements Filter {
        @Override
        public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
                throws IOException, ServletException {
            HttpServletResponse response = (HttpServletResponse) res;
            HttpServletRequest request = (HttpServletRequest) req;

            String origin = request.getHeader("Origin");
            if (origin != null) {
                response.setHeader("Access-Control-Allow-Origin", origin);
            } else {
                response.setHeader("Access-Control-Allow-Origin", "*");
            }
            response.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
            response.setHeader("Access-Control-Allow-Headers", "*");
            response.setHeader("Access-Control-Allow-Credentials", "true");
            response.setHeader("Access-Control-Expose-Headers", "Authorization");
            response.setHeader("Access-Control-Max-Age", "3600");

            if ("OPTIONS".equalsIgnoreCase(request.getMethod())) {
                response.setStatus(HttpServletResponse.SC_OK);
                return;
            }

            chain.doFilter(req, res);
        }
    }
}