muonsoft / validation

import "errors"

var (

	ErrTooShort          = errors.New("too short")

	ErrTooLong           = errors.New("too long")

	ErrTooLarge          = errors.New("too large")

	ErrInvalidCharacters = errors.New("invalid characters")

)

var ulidChars = newCharSet("0123456789ABCDEFGHJKMNPQRSTVWXYZabcdefghjkmnpqrstvwxyz")

// ULID validates whether the value is a valid ULID (Universally Unique Lexicographically Sortable Identifier).

// See https://github.com/ulid/spec for ULID specifications.

//

// Possible errors:

//   - [ErrTooShort] on values with length less than 26;

//   - [ErrTooLong] on values with length greater than 26;

//   - [ErrInvalidCharacters] on values with unexpected characters;

//   - [ErrTooLarge] on too big value (larger than '7ZZZZZZZZZZZZZZZZZZZZZZZZZ').

func ULID(value string) error {

	if len(value) < 26 {

		return ErrTooShort

	}

	if len(value) > 26 {

		return ErrTooLong

	}

	for _, c := range value {

		if !ulidChars.Contains(c) {

			return ErrInvalidCharacters

		}

	}

	// Largest valid ULID is '7ZZZZZZZZZZZZZZZZZZZZZZZZZ'

	// See https://github.com/ulid/spec#overflow-errors-when-parsing-base32-strings

	if value[0] > '7' {

		return ErrTooLarge

	}

	return nil

}

type charSet map[rune]struct{}

func (s charSet) Contains(c rune) bool {

	_, exist := s[c]

	return exist

}