address.go

package email

import (
	"regexp"
	"strings"
)

var emailRegexp *regexp.Regexp = regexp.MustCompile(`[a-zA-Z0-9\-+~_%]+[a-zA-Z0-9\-+~_%.]*@([a-z0-9]+[a-z0-9\-]*\.)+[a-z][a-z]+`)

// NormalizeAddress trims space and converts the domain to lower case.
func NormalizeAddress(address string) string {
	address = strings.TrimSpace(address)
	i := strings.Index(address, "@")
	if i == -1 {
		return address
	}
	return address[:i+1] + strings.ToLower(address[i+1:])
}

func NormalizeAddressLowercase(address string) string {
	return strings.ToLower(strings.TrimSpace(address))
}

func CompareAddressesCaseinsensitive(addressA, addressB string) bool {
	return NormalizeAddressLowercase(addressA) == NormalizeAddressLowercase(addressB)
}

// ValidateAddress uses a simplified regular expression for checking
// email addresses. Please report real world addresses that are not working as bug.
func ValidateAddress(address string) (normalizedAddress string, err error) {
	normalizedAddress = NormalizeAddress(address)
	valid := emailRegexp.Match([]byte(normalizedAddress))
	if !valid {
		return "", ErrInvalidEmailAddress(address)
	}
	return normalizedAddress, nil
}

type ErrInvalidEmailAddress string

func (self ErrInvalidEmailAddress) Error() string {
	return "Invalid email address: " + string(self)
}