chore: Clean converter code and add doc

common/convert/base64.go

@@ -0,0 +1,45 @@
+package convert
+
+import (
+	"encoding/base64"
+	"strings"
+)
+
+var (
+	encRaw = base64.RawStdEncoding
+	enc    = base64.StdEncoding
+)
+
+// DecodeBase64 try to decode content from the given bytes,
+// which can be in base64.RawStdEncoding, base64.StdEncoding or just plaintext.
+func DecodeBase64(buf []byte) []byte {
+	result, err := tryDecodeBase64(buf)
+	if err != nil {
+		return buf
+	}
+	return result
+}
+
+func tryDecodeBase64(buf []byte) ([]byte, error) {
+	dBuf := make([]byte, encRaw.DecodedLen(len(buf)))
+	n, err := encRaw.Decode(dBuf, buf)
+	if err != nil {
+		n, err = enc.Decode(dBuf, buf)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return dBuf[:n], nil
+}
+
+func urlSafe(data string) string {
+	return strings.NewReplacer("+", "-", "/", "_").Replace(data)
+}
+
+func decodeUrlSafe(data string) string {
+	dcBuf, err := base64.RawURLEncoding.DecodeString(data)
+	if err != nil {
+		return ""
+	}
+	return string(dcBuf)
+}

common/convert/converter.go

@@ -2,7 +2,6 @@ package convert
 
 import (
 	"bytes"
-	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"net/url"
@@ -10,23 +9,6 @@ import (
 	"strings"
 )
 
-var (
-	encRaw = base64.RawStdEncoding
-	enc    = base64.StdEncoding
-)
-
-func DecodeBase64(buf []byte) []byte {
-	dBuf := make([]byte, encRaw.DecodedLen(len(buf)))
-	n, err := encRaw.Decode(dBuf, buf)
-	if err != nil {
-		n, err = enc.Decode(dBuf, buf)
-		if err != nil {
-			return buf
-		}
-	}
-	return dBuf[:n]
-}
-
 // ConvertsV2Ray convert V2Ray subscribe proxies data to clash proxies config
 func ConvertsV2Ray(buf []byte) ([]map[string]any, error) {
 	data := DecodeBase64(buf)
@@ -450,18 +432,6 @@ func ConvertsV2Ray(buf []byte) ([]map[string]any, error) {
 	return proxies, nil
 }
 
-func urlSafe(data string) string {
-	return strings.ReplaceAll(strings.ReplaceAll(data, "+", "-"), "/", "_")
-}
-
-func decodeUrlSafe(data string) string {
-	dcBuf, err := base64.RawURLEncoding.DecodeString(data)
-	if err != nil {
-		return ""
-	}
-	return string(dcBuf)
-}
-
 func uniqueName(names map[string]int, name string) string {
 	if index, ok := names[name]; ok {
 		index++