site clone with golang

go

package main 

import (
    "log"
    "io"
    "strings"
    "net/http"
    _ "bufio"
    "net/url"
    "io/ioutil"
    "os"
    "path/filepath"
)

type MyHandler struct {

}

var sourceDomain string = ""
var downloadFolder string = ""

func copyHeaders(dst, src http.Header) {
    for k, _ := range dst {
        dst.Del(k)
    }

    for k, vs := range src {
        for _, v := range vs {
            dst.Add(k, v)
        }
    }
}

func (handler *MyHandler) fakeIt(uri string, req *http.Request) (res *http.Response){
    url := strings.Join([]string{sourceDomain, uri}, "")
    method := req.Method
    formData := req.PostForm
    log.Printf("Fetch from %s and method %s and data %s", url, method, formData.Encode())

    if method == "GET" {
        client := &http.Client{}
        resp, _ := client.Get(url)

        return resp
    } else if method == "POST" {
        // TODO:: 
        log.Printf("暂时不支持 POST")
    }

    return nil
}

func (handler *MyHandler) generateFileHandler(uri string, req *http.Request) (w *os.File){

    domainName := strings.Replace(sourceDomain, "https://", "", 1)
    log.Printf("Domain name is %s", domainName)

    downloadDir := filepath.Join(downloadFolder, domainName)
    err := os.MkdirAll(downloadDir, 0766)
    if err != nil {
        log.Fatal("创建主目录失败")
    }
    log.Printf("创建主目录成功")

    // 根据uri 来创建目录
    URLObj, _ := url.Parse(uri)
    simplerURI := URLObj.RequestURI()

    subDir := simplerURI[1:]

    // 检查是不是 HTML 文件
    dotIndex := strings.LastIndex(simplerURI, ".")
    if dotIndex == -1 {
        subDir = strings.Join([]string{subDir, "html"}, ".")
    }

    downloadFileTo := filepath.Join(downloadDir, subDir)
    log.Printf("下载到: %s", downloadFileTo)

    downloadFileDir := filepath.Dir(downloadFileTo)
    err = os.MkdirAll(downloadFileDir, 0777) 

    if err != nil {
        log.Printf("创建下载目录 %s 失败 %v", downloadFileDir, err)
    }

    var f *os.File
    if _, err = os.Stat(downloadFileTo); os.IsNotExist(err) {

        f, err = os.Create(downloadFileTo)
        if err != nil {
            log.Printf("创建 %s 文件失败 %v ", downloadFileTo, err)
        }
    } else {
        f, _ = os.Open(downloadFileTo)
        log.Printf("文件已存在 %s ", downloadFileTo)
    }

    return f

}

// HTTP 服务器
func (handler *MyHandler) ServeHTTP (w http.ResponseWriter, req *http.Request) {
    uri := req.URL.String()
    resp := handler.fakeIt(uri, req)

    log.Printf("Status: %s ", resp.Status)

    copyHeaders(w.Header(), resp.Header)
    w.WriteHeader(resp.StatusCode)

    fileHandler := handler.generateFileHandler(uri, req)

    contentBodyBytes, _ := ioutil.ReadAll(resp.Body)

    contentStr := string(contentBodyBytes)

    if uri == "/activity" {
        changeContentStr := strings.Replace(contentStr, "./build", "/activity/build", -1)
        contentBodyBytes = []byte(changeContentStr)
    }

    fileHandler.Write(contentBodyBytes)

    fileHandler.Seek(0, 0)

    nr, err := io.Copy(w, fileHandler)

    log.Printf("Content copied %v and error is %v (the response body content length is %d )", nr, err, resp.ContentLength)

    //defer resp.Body.Close()
    defer fileHandler.Close()

}

func main() {
    handler := MyHandler{}
    log.Printf("%s", "Server Listen on :8182")
    http.ListenAndServe(":8182", &handler)