// Package proxy...
//
// Description : 正向代理的实现
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2021-08-06 2:07 下午
package proxy

import (
	"compress/gzip"
	"io"
	"io/ioutil"
	"net/http"
	"net/http/httputil"
	"strings"
)

// Forward 正向代理的实现
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2:08 下午 2021/8/6
func Forward(rw http.ResponseWriter, req *http.Request, serverConfig *Server) {

	if !strings.HasPrefix(serverConfig.URI, "/") {
		serverConfig.URI = "/" + serverConfig.URI
	}
	// 请求重写方法
	director := func(req *http.Request) {
		req.URL.Scheme = serverConfig.Scheme
		// req.URL.Host = projectDetail.GetProjectDetail().Domain + ":" + fmt.Sprintf("%v", projectDetail.GetProjectDetail().Port)
		// req.Host = projectDetail.GetProjectDetail().Domain + ":" + fmt.Sprintf("%v", projectDetail.GetProjectDetail().Port)
		req.Host = serverConfig.Host
		req.URL.Host = serverConfig.Host
		req.URL.Path = serverConfig.URI
		req.RequestURI = serverConfig.URI
		// 写入重写的请求Header
		for k, v := range serverConfig.RewriteRequestHeader {
			req.Header.Set(k, v)
		}
	}
	// TODO : 重写响应数据
	modifyResponseFunc := func(rep *http.Response) error {
		return nil
	}
	p := &httputil.ReverseProxy{Director: director, ModifyResponse: modifyResponseFunc}
	p.ServeHTTP(rw, req)
}

// getResultCompressType 获取返回结果的压缩方式
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 9:11 下午 2021/9/11
func getResultCompressType(res *http.Response) string {
	return strings.ToLower(res.Header.Get("Content-Encoding"))
}

// getResponseData 解析响应数据
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 9:15 下午 2021/9/11
func getResponseData(res *http.Response) ([]byte, error) {
	var (
		responseData []byte
		err          error
	)
	switch getResultCompressType(res) {
	case "gzip":
		var gzipData io.Reader
		if gzipData, err = gzip.NewReader(res.Body); nil == err {
			// gzip 处理过的数据
			responseData, err = ioutil.ReadAll(gzipData)
		}
	default:
		// 默认没有任何压缩
		responseData, err = io.ReadAll(res.Body)
	}
	return responseData, err
}