feat: finalize Go backend migration and deployment cutover

go-backend/internal/http/handler/captcha_state.go

@@ -0,0 +1,67 @@
+package handler
+
+import "time"
+
+const captchaTokenTTL = 5 * time.Minute
+
+func (h *Handler) storeCaptchaToken(token string) {
+	if h == nil {
+		return
+	}
+	token = normalizeCaptchaToken(token)
+	if token == "" {
+		return
+	}
+
+	h.captchaMu.Lock()
+	defer h.captchaMu.Unlock()
+
+	now := time.Now().UnixMilli()
+	h.pruneExpiredCaptchaTokensLocked(now)
+	h.captchaTokens[token] = now + int64(captchaTokenTTL/time.Millisecond)
+}
+
+func (h *Handler) consumeCaptchaToken(token string) bool {
+	if h == nil {
+		return false
+	}
+	token = normalizeCaptchaToken(token)
+	if token == "" {
+		return false
+	}
+
+	h.captchaMu.Lock()
+	defer h.captchaMu.Unlock()
+
+	now := time.Now().UnixMilli()
+	h.pruneExpiredCaptchaTokensLocked(now)
+	expiresAt, ok := h.captchaTokens[token]
+	if !ok || expiresAt <= now {
+		delete(h.captchaTokens, token)
+		return false
+	}
+	delete(h.captchaTokens, token)
+	return true
+}
+
+func (h *Handler) pruneExpiredCaptchaTokensLocked(now int64) {
+	for token, expiresAt := range h.captchaTokens {
+		if expiresAt <= now {
+			delete(h.captchaTokens, token)
+		}
+	}
+}
+
+func normalizeCaptchaToken(token string) string {
+	return trimToken(token)
+}
+
+func trimToken(token string) string {
+	for len(token) > 0 && (token[0] == ' ' || token[0] == '\t' || token[0] == '\n' || token[0] == '\r') {
+		token = token[1:]
+	}
+	for len(token) > 0 && (token[len(token)-1] == ' ' || token[len(token)-1] == '\t' || token[len(token)-1] == '\n' || token[len(token)-1] == '\r') {
+		token = token[:len(token)-1]
+	}
+	return token
+}