feat: add Kiro OAuth web, rate limiter, metrics, fingerprint, background refresh and model converter

internal/translator/kiro/common/utf8_stream.go

@@ -0,0 +1,97 @@
+package common
+
+import (
+	"unicode/utf8"
+)
+
+type UTF8StreamParser struct {
+	buffer []byte
+}
+
+func NewUTF8StreamParser() *UTF8StreamParser {
+	return &UTF8StreamParser{
+		buffer: make([]byte, 0, 64),
+	}
+}
+
+func (p *UTF8StreamParser) Write(data []byte) {
+	p.buffer = append(p.buffer, data...)
+}
+
+func (p *UTF8StreamParser) Read() (string, bool) {
+	if len(p.buffer) == 0 {
+		return "", false
+	}
+
+	validLen := p.findValidUTF8End(p.buffer)
+	if validLen == 0 {
+		return "", false
+	}
+
+	result := string(p.buffer[:validLen])
+	p.buffer = p.buffer[validLen:]
+
+	return result, true
+}
+
+func (p *UTF8StreamParser) Flush() string {
+	if len(p.buffer) == 0 {
+		return ""
+	}
+	result := string(p.buffer)
+	p.buffer = p.buffer[:0]
+	return result
+}
+
+func (p *UTF8StreamParser) Reset() {
+	p.buffer = p.buffer[:0]
+}
+
+func (p *UTF8StreamParser) findValidUTF8End(data []byte) int {
+	if len(data) == 0 {
+		return 0
+	}
+
+	end := len(data)
+	for i := 1; i <= 3 && i <= len(data); i++ {
+		b := data[len(data)-i]
+		if b&0x80 == 0 {
+			break
+		}
+		if b&0xC0 == 0xC0 {
+			size := p.utf8CharSize(b)
+			available := i
+			if size > available {
+				end = len(data) - i
+			}
+			break
+		}
+	}
+
+	if end > 0 && !utf8.Valid(data[:end]) {
+		for i := end - 1; i >= 0; i-- {
+			if utf8.Valid(data[:i+1]) {
+				return i + 1
+			}
+		}
+		return 0
+	}
+
+	return end
+}
+
+func (p *UTF8StreamParser) utf8CharSize(b byte) int {
+	if b&0x80 == 0 {
+		return 1
+	}
+	if b&0xE0 == 0xC0 {
+		return 2
+	}
+	if b&0xF0 == 0xE0 {
+		return 3
+	}
+	if b&0xF8 == 0xF0 {
+		return 4
+	}
+	return 1
+}