utils/validators.go

package utils

import (
	"net/url"
	"os"
	"regexp"

	"github.com/google/uuid"
)

// DoesFileExist returns true, if a file exists (and actually is a file)
func DoesFileExist(p string) bool {
	s, err := os.Stat(p)
	if os.IsNotExist(err) {
		return false
	}

	if s.IsDir() {
		return false
	}

	return true
}

// DoesFolderExist returns true, if a folder exists (and actually is a folder)
func DoesFolderExist(p string) bool {
	s, err := os.Stat(p)
	if os.IsNotExist(err) {
		return false
	}

	if !s.IsDir() {
		return false
	}

	return true
}

// DoesStringContainsNonWhitelistedSubstrings returns false if s contains substrings which are not in whitelist
func DoesStringContainsNonWhitelistedSubstrings(s string, whitelist map[string]string) bool {
	for _, char := range s {
		_, charIsWhitelisted := whitelist[string(char)]
		if !charIsWhitelisted {
			return true
		}
	}

	return false
}

// IsStringInSliceOfStrings returns true, if slice contains target
func IsStringInSliceOfStrings(slice []string, target string) bool {
	for _, v := range slice {
		if v == target {
			return true
		}
	}

	return false
}

// IsValidEmail returns true, if s is a email address.
func IsValidEmail(s string) bool {
	// Used Regex instead of mail.ParseAddress(), as the latter incorrectly recognizes samples such as “bad@domain” as a valid address
	// Shoutout to emailregex.com for the almighty regular expression
	return regexp.MustCompile(
		`(?:[a-z0-9!#$%&'*+/=?^_{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])`,
	).MatchString(s)
}

// IsValidURL returns true, if s is a valid URL
func IsValidURL(s string) bool {
	u, err := url.Parse(s)
	if err != nil || u.Scheme == "" || u.Host == "" {
		return false
	}

	return true
}

// IsValidUUID returns true, if s is a valid UUID
func IsValidUUID(s string) bool {
	_, err := uuid.Parse(s)
	return err == nil
}