muonsoft / validation

import (

	"errors"

	"net/url"

)

var (

	ErrUnexpectedProtocol = errors.New("unexpected protocol")

)

// URL is used to validate that value is a valid absolute URL string, which means that a protocol (or scheme)

// is required. By default (if no protocols are passed), the function checks only for

// the http:// and https:// protocols. Use the protocols argument to configure the list of expected protocols.

//

// If value is not a valid URL the function will return one of the errors:

//	• parsing error from url.Parse method if value cannot be parsed as an URL;

//	• ErrUnexpectedProtocol if protocol is not matching one of the listed protocols;

//	• ErrInvalid if value is not matching the regular expression.

func URL(value string, protocols ...string) error {

	return validateURL(value, false, protocols...)

}

// RelativeURL is used to validate that value is a valid absolute or relative URL string. The protocol is considered

// optional when validating the syntax of the given URL. This means that both http:// and https:// are valid

// but also relative URLs that contain no protocol (e.g. //example.com). By default, the function checks

// only for the http:// and https:// protocols. Use the protocols argument to configure

// the list of expected protocols.

//

// If value is not a valid URL the function will return one of the errors:

//	• parsing error from url.Parse method if value cannot be parsed as an URL;

//	• ErrUnexpectedProtocol if protocol is not matching one of the listed protocols or it is not a relative URL;

//	• ErrInvalid if value is not matching the regular expression.

func RelativeURL(value string, protocols ...string) error {

	return validateURL(value, true, protocols...)

}

func validateProtocol(u *url.URL, isRelative bool, protocols []string) error {

	if isRelative && u.Scheme == "" {

		return nil

	}

	for _, protocol := range protocols {

		if protocol == u.Scheme {

			return nil

		}

	}

	return ErrUnexpectedProtocol

}