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package deeplink
import (
"github.com/go-faster/errors"
"github.com/gotd/td/internal/ascii"
)
// ValidateDomain validate given domain (user) name
func ValidateDomain(domain string) error {
return checkDomainSymbols(domain)
}
// checkDomainSymbols check that domain contains only a-z, A-Z, 0-9 and '_'
// symbols.
func checkDomainSymbols(domain string) error {
switch {
case domain == "":
return errors.New("is empty")
case len(domain) > 32:
return errors.New("is too big")
case !ascii.IsLatinLower(rune(domain[0])):
return errors.New("must start with lower letter")
case domain[len(domain)-1] == '_':
return errors.New("must not end with '_'")
}
for i, r := range domain {
switch {
case !ascii.IsLatinLetter(r) && !ascii.IsDigit(r) && r != '_':
case i > 0 && domain[i] == '_' && domain[i] == domain[i-1]:
default:
continue
}
return errors.Errorf("unexpected %c at %d", r, i)
}
return nil
}