package main

import (

"bytes"

"errors"

"encoding/base64"

"crypto/md5"

"fmt"

"io"

"io/ioutil"

"net/http"

)

// *** Hash Functions ***

func key2path(key []byte) string {

mkey := md5.Sum(key)

b64key := base64.StdEncoding.EncodeToString(key)

// 2 byte layers deep, meaning a fanout of 256

// optimized for 2^24 = 16M files per volume server

return fmt.Sprintf("/%02x/%02x/%s", mkey[0], mkey[1], b64key)

}

func key2volume(key []byte, volumes []string) string {

// this is an intelligent way to pick the volume server for a file

// stable in the volume server name (not position!)

// and if more are added the correct portion will move (yay md5!)

var best_score []byte = nil

var ret string = ""

for _, v := range volumes {

hash := md5.New()

hash.Write(key)

hash.Write([]byte(v))

score := hash.Sum(nil)

if best_score == nil || bytes.Compare(best_score, score) == -1 {

best_score = score

ret = v

}

}

//fmt.Println(string(key), ret, best_score)

return ret

}

// *** Remote Access Functions ***

func remote_delete(remote string) error {

req, err := http.NewRequest("DELETE", remote, nil)

if err != nil {

return err

}

resp, err := http.DefaultClient.Do(req)

if err != nil {

return err

}

defer resp.Body.Close()

if resp.StatusCode != 204 {

return fmt.Errorf("remote_delete: wrong status code %d", resp.StatusCode)

}

return nil

}

func remote_put(remote string, length int64, body io.Reader) error {

req, err := http.NewRequest("PUT", remote, body)

if err != nil {

return err

}

req.ContentLength = length

resp, err := http.DefaultClient.Do(req)

if err != nil {

return err

}

defer resp.Body.Close()

if resp.StatusCode != 201 && resp.StatusCode != 204 {

return fmt.Errorf("remote_put: wrong status code %d", resp.StatusCode)

}

return nil

}

func remote_get(remote string) (string, error) {

resp, err := http.Get(remote)

if err != nil {

return "", err

}

if resp.StatusCode != 200 {

return "", errors.New(fmt.Sprintf("remote_get: wrong status code %d", resp.StatusCode))

}

defer resp.Body.Close()

body, err := ioutil.ReadAll(resp.Body)

if err != nil {

return "", err

}

return string(body), nil

}