package server

import (
	"errors"
	"strconv"
	"strings"
)

const (
	_byte     = 1
	kilobyte = _byte * 1000
	megabyte = kilobyte * 1000
	gigabyte = megabyte * 1000
)

func parseBandwidth(s string) (uint64, error) {
	s = strings.ToLower(strings.TrimSpace(s))
	split := 0
	for i, c := range s {
		if c < '0' || c > '9' {
			split = i
			break
		}
	}
	if split == 0 {
		return 0, errors.New("invalid bandwidth format")
	}
	v, err := strconv.ParseUint(s[:split], 10, 64)
	if err != nil {
		return 0, err
	}
	unit := strings.TrimSpace(s[split:])

	switch unit {
	case "b", "bps":
		return v / 8, nil
	case "k", "kb", "kbps":
		return v * kilobyte / 8, nil
	case "m", "mb", "mbps":
		return v * megabyte / 8, nil
	case "g", "gb", "gbps":
		return v * gigabyte / 8, nil
	default:
		return 0, errors.New("unsupported bandwidth unit")
	}
}