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
}