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|
package resolver
import (
"encoding/base64"
"fmt"
"net/url"
"strings"
)
type DataURL struct {
mimeType string
data string
isBase64 bool
}
func ParseDataURL(url string) (parsed DataURL, ok bool) {
if strings.HasPrefix(url, "data:") {
if comma := strings.IndexByte(url, ','); comma != -1 {
parsed.mimeType = url[len("data:"):comma]
parsed.data = url[comma+1:]
if strings.HasSuffix(parsed.mimeType, ";base64") {
parsed.mimeType = parsed.mimeType[:len(parsed.mimeType)-len(";base64")]
parsed.isBase64 = true
}
ok = true
}
}
return
}
type MIMEType uint8
const (
MIMETypeUnsupported MIMEType = iota
MIMETypeTextCSS
MIMETypeTextJavaScript
MIMETypeApplicationJSON
)
func (parsed DataURL) DecodeMIMEType() MIMEType {
// Remove things like ";charset=utf-8"
mimeType := parsed.mimeType
if semicolon := strings.IndexByte(mimeType, ';'); semicolon != -1 {
mimeType = mimeType[:semicolon]
}
// Hard-code a few supported types
switch mimeType {
case "text/css":
return MIMETypeTextCSS
case "text/javascript":
return MIMETypeTextJavaScript
case "application/json":
return MIMETypeApplicationJSON
default:
return MIMETypeUnsupported
}
}
func (parsed DataURL) DecodeData() (string, error) {
// Try to read base64 data
if parsed.isBase64 {
bytes, err := base64.StdEncoding.DecodeString(parsed.data)
if err != nil {
return "", fmt.Errorf("could not decode base64 data: %s", err.Error())
}
return string(bytes), nil
}
// Try to read percent-escaped data
content, err := url.PathUnescape(parsed.data)
if err != nil {
return "", fmt.Errorf("could not decode percent-escaped data: %s", err.Error())
}
return content, nil
}
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