🎨 新增兑换码功能，新增vip过期检测定时任务

utils/rand_code.go

@@ -9,6 +9,7 @@ import (
 
 const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 
+// GenerateInviteCode 生成邀请码，基于用户ID和随机数的MD5哈希
 func GenerateInviteCode(userID uint) string {
 	rand.Seed(time.Now().UnixNano())
 	// 拼接用户ID和随机数
@@ -34,3 +35,28 @@ func GenerateRandomString(length int) string {
 	}
 	return code
 }
+
+// GenerateRedeemCode 生成单个兑换码，格式为N7DY4kcf5z37hwz，随机大小写字母+数字
+func GenerateRedeemCode() string {
+	const codeCharset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	codeLen := 15
+	b := make([]byte, codeLen)
+	for i := range b {
+		b[i] = codeCharset[rand.Intn(len(codeCharset))]
+	}
+	return string(b)
+}
+
+// GenerateRedeemCodes 批量生成唯一兑换码，number为生成数量
+func GenerateRedeemCodes(number int) []string {
+	codesMap := make(map[string]struct{}, number)
+	for len(codesMap) < number {
+		code := GenerateRedeemCode()
+		codesMap[code] = struct{}{}
+	}
+	codes := make([]string, 0, number)
+	for code := range codesMap {
+		codes = append(codes, code)
+	}
+	return codes
+}