package com.nepxion.discovery.plugin.strategy.service.aop;

/**
 * <p>Title: Nepxion Discovery</p>
 * <p>Description: Nepxion Discovery</p>
 * <p>Copyright: Copyright (c) 2017-2050</p>
 * <p>Company: Nepxion</p>
 * @author Haojun Ren
 * @version 1.0
 */

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

public class RestTemplateStrategyInterceptor implements ClientHttpRequestInterceptor {
    private static final Logger LOG = LoggerFactory.getLogger(RestTemplateStrategyInterceptor.class);

    private String requestHeaders;

    public RestTemplateStrategyInterceptor(String requestHeaders) {
        this.requestHeaders = requestHeaders.toLowerCase();

        LOG.info("------------- RestTemplate Proxy Information -----------");
        LOG.info("RestTemplate interceptor headers are '{}'", requestHeaders);
        LOG.info("-------------------------------------------------");
    }

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {     
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        if (attributes == null) {
            return execution.execute(request, body);
        }

        HttpServletRequest previousRequest = attributes.getRequest();

        Enumeration<String> headerNames = previousRequest.getHeaderNames();
        if (headerNames == null) {
            return execution.execute(request, body);
        }

        HttpHeaders headers = request.getHeaders();

        while (headerNames.hasMoreElements()) {
            String headerName = headerNames.nextElement();
            String header = previousRequest.getHeader(headerName);

            if (requestHeaders.contains(headerName.toLowerCase())) {
                headers.add(headerName, header);
            }
        }

        return execution.execute(request, body);
    }
}