分享码有效期，支持表达式

internal/config/share_code_ttl.go

@@ -0,0 +1,59 @@
+package config
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const shareCodeTTLMax = 365 * 24 * time.Hour
+
+// parseShareCodeTTL parses SHARE_CODE_TTL_MIN values:
+//   - bare number (e.g. "30") = minutes (backward compatible)
+//   - with suffix: m (minutes), h (hours), d (days), e.g. "30m", "24h", "30d"
+func parseShareCodeTTL(raw string) (time.Duration, error) {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return 30 * time.Minute, nil
+	}
+
+	if n, err := strconv.Atoi(raw); err == nil {
+		if n <= 0 {
+			return 0, fmt.Errorf("must be positive")
+		}
+		d := time.Duration(n) * time.Minute
+		if d > shareCodeTTLMax {
+			return 0, fmt.Errorf("exceeds maximum of 365d")
+		}
+		return d, nil
+	}
+
+	if len(raw) < 2 {
+		return 0, fmt.Errorf("invalid format %q", raw)
+	}
+
+	unit := strings.ToLower(string(raw[len(raw)-1]))
+	numStr := raw[:len(raw)-1]
+	n, err := strconv.Atoi(numStr)
+	if err != nil || n <= 0 {
+		return 0, fmt.Errorf("invalid format %q", raw)
+	}
+
+	var d time.Duration
+	switch unit {
+	case "m":
+		d = time.Duration(n) * time.Minute
+	case "h":
+		d = time.Duration(n) * time.Hour
+	case "d":
+		d = time.Duration(n) * 24 * time.Hour
+	default:
+		return 0, fmt.Errorf("unknown unit %q (use m, h, or d)", unit)
+	}
+
+	if d > shareCodeTTLMax {
+		return 0, fmt.Errorf("exceeds maximum of 365d")
+	}
+	return d, nil
+}