/
asset_client.go
127 lines (107 loc) · 3.35 KB
/
asset_client.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
package main
import (
"flag"
"fmt"
log "github.com/echocat/slf4g"
"io"
"io/ioutil"
"mime"
"net/http"
"os"
"path/filepath"
"sync"
)
var (
assetsFolder = flag.String("assets", "assets", "Folder to put downloaded assets to.")
)
type assetClient struct {
cache map[string]string
mutex sync.Mutex
}
func newAssetClient() *assetClient {
return &assetClient{
cache: make(map[string]string),
}
}
func (instance *assetClient) retrieve(sourceUrl string) (resultAsset string, err error) {
instance.mutex.Lock()
defer instance.mutex.Unlock()
l := log.With("url", sourceUrl)
defer func() {
if err == nil {
l.With("file", resultAsset).Info("Asset downloaded.")
}
}()
if cached := instance.cache[sourceUrl]; cached != "" {
return cached, nil
}
resp, err := http.Get(sourceUrl)
if err != nil {
return "", fmt.Errorf("cannot download '%s': %w", sourceUrl, err)
}
if resp.Body == nil {
return "", fmt.Errorf("no response body while try to download '%s': %d - %s", sourceUrl, resp.StatusCode, resp.Status)
}
defer func() {
if cErr := resp.Body.Close(); cErr != nil && err == nil {
err = cErr
}
}()
if resp.StatusCode != http.StatusOK {
return "", fmt.Errorf("unexpected status while try to download '%s': %d - %s", sourceUrl, resp.StatusCode, resp.Status)
}
contentType := resp.Header.Get("Content-Type")
if contentType == "" {
return "", fmt.Errorf("no Content-Type header present try to download '%s': %d - %s", sourceUrl, resp.StatusCode, resp.Status)
}
ext, err := instance.contentTypeToExt(contentType, sourceUrl)
if err != nil {
return "", err
}
return instance.retrieveFromReader(resp.Body, sourceUrl, ext)
}
func (instance *assetClient) contentTypeToExt(contentType, sourceUrl string) (string, error) {
ext, err := mime.ExtensionsByType(contentType)
if err != nil {
return "", fmt.Errorf("illegal Content-Type header present try to download '%s': %s - %w", sourceUrl, contentType, err)
}
if len(ext) <= 0 {
return "", fmt.Errorf("illegal Content-Type header present try to download '%s': %s", sourceUrl, contentType)
}
for _, candidate := range ext {
if candidate == ".jpg" {
return candidate, nil
}
}
return ext[0], nil
}
func (instance *assetClient) retrieveFromReader(source io.Reader, sourceRef, ext string) (string, error) {
if err := os.MkdirAll(*assetsFolder, 755); err != nil {
return "", fmt.Errorf("cannot create target folder '%s' to store the '%s' inside: %w", *assetsFolder, sourceRef, err)
}
w, err := ioutil.TempFile(*assetsFolder, "~*"+ext)
if err != nil {
return "", fmt.Errorf("cannot temporary file: %w", err)
}
defer func() {
_ = w.Close()
}()
r := newSha256reader(source)
if _, err = io.Copy(w, r); err != nil {
return "", fmt.Errorf("cannot download '%s' to '%s': %w", sourceRef, w.Name(), err)
}
if err := w.Close(); err != nil {
return "", fmt.Errorf("cannot closed '%s' after downloaded from '%s': %w", w.Name(), sourceRef, err)
}
target := filepath.Join(*assetsFolder, fmt.Sprintf("%s%s", r.SumString(), ext))
if err := os.Rename(w.Name(), target); err != nil {
return "", fmt.Errorf("cannot rename '%s' to '%s' after downloaded from '%s': %w", w.Name(), target, sourceRef, err)
}
return filepath.Base(target), nil
}
func (instance *assetClient) cleanTarget() error {
if err := os.RemoveAll(*assetsFolder); err != nil && !os.IsNotExist(err) {
return err
}
return nil
}