完成客服工作台闭环

server/internal/handler/message_validation.go

@@ -0,0 +1,45 @@
+package handler
+
+import (
+	"encoding/base64"
+	"errors"
+	"strings"
+	"unicode/utf8"
+)
+
+const (
+	maxTextMessageLength = 2000
+	maxImageMessageSize  = 5 * 1024 * 1024
+)
+
+func validateMessageContent(messageType, content string) (string, error) {
+	switch messageType {
+	case "text":
+		content = strings.TrimSpace(content)
+		if content == "" {
+			return "", errors.New("消息内容不能为空")
+		}
+		if utf8.RuneCountInString(content) > maxTextMessageLength {
+			return "", errors.New("单条文本消息不能超过 2000 字")
+		}
+		return content, nil
+	case "image":
+		parts := strings.SplitN(content, ",", 2)
+		if len(parts) != 2 {
+			return "", errors.New("图片格式无效")
+		}
+		if parts[0] != "data:image/jpeg;base64" && parts[0] != "data:image/png;base64" && parts[0] != "data:image/gif;base64" {
+			return "", errors.New("仅支持 jpg、png、gif 图片")
+		}
+		bytes, err := base64.StdEncoding.DecodeString(parts[1])
+		if err != nil || len(bytes) == 0 {
+			return "", errors.New("图片内容无效")
+		}
+		if len(bytes) > maxImageMessageSize {
+			return "", errors.New("图片不能超过 5 MB")
+		}
+		return content, nil
+	default:
+		return "", errors.New("不支持的消息类型")
+	}
+}