feat/ai proxy vertex ai compatible (#3324)

plugins/wasm-go/extensions/ai-proxy/util/string.go

@@ -1,6 +1,10 @@
 package util
 
-import "regexp"
+import (
+	"regexp"
+	"strconv"
+	"strings"
+)
 
 func StripPrefix(s string, prefix string) string {
 	if len(prefix) != 0 && len(s) >= len(prefix) && s[0:len(prefix)] == prefix {
@@ -18,3 +22,43 @@ func MatchStatus(status string, patterns []string) bool {
 	}
 	return false
 }
+
+// unicodeEscapeRegex matches Unicode escape sequences like \uXXXX
+var unicodeEscapeRegex = regexp.MustCompile(`\\u([0-9a-fA-F]{4})`)
+
+// DecodeUnicodeEscapes decodes Unicode escape sequences (\uXXXX) in a string to UTF-8 characters.
+// This is useful when a JSON response contains ASCII-safe encoded non-ASCII characters.
+func DecodeUnicodeEscapes(input []byte) []byte {
+	result := unicodeEscapeRegex.ReplaceAllFunc(input, func(match []byte) []byte {
+		// match is like \uXXXX, extract the hex part (XXXX)
+		hexStr := string(match[2:6])
+		codePoint, err := strconv.ParseInt(hexStr, 16, 32)
+		if err != nil {
+			return match // return original if parse fails
+		}
+		return []byte(string(rune(codePoint)))
+	})
+	return result
+}
+
+// DecodeUnicodeEscapesInSSE decodes Unicode escape sequences in SSE formatted data.
+// It processes each line that starts with "data: " and decodes Unicode escapes in the JSON payload.
+func DecodeUnicodeEscapesInSSE(input []byte) []byte {
+	lines := strings.Split(string(input), "\n")
+	var result strings.Builder
+	for i, line := range lines {
+		if strings.HasPrefix(line, "data: ") {
+			// Decode Unicode escapes in the JSON payload
+			jsonData := line[6:]
+			decodedData := DecodeUnicodeEscapes([]byte(jsonData))
+			result.WriteString("data: ")
+			result.Write(decodedData)
+		} else {
+			result.WriteString(line)
+		}
+		if i < len(lines)-1 {
+			result.WriteString("\n")
+		}
+	}
+	return []byte(result.String())
+}