Implement owner setup and browser authentication sessions

internal/domain/identity.go

@@ -0,0 +1,73 @@
+package domain
+
+import (
+	"errors"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"golang.org/x/text/cases"
+	"golang.org/x/text/unicode/norm"
+)
+
+const (
+	MinimumPasswordRunes = 12
+	MaximumPasswordBytes = 1024
+	MaximumIdentityRunes = 128
+)
+
+var (
+	ErrInvalidUsername    = errors.New("invalid username")
+	ErrInvalidDisplayName = errors.New("invalid display name")
+	ErrInvalidPassword    = errors.New("invalid password")
+)
+
+type OwnerIdentity struct {
+	Username    string
+	UsernameKey string
+	DisplayName string
+}
+
+func NewOwnerIdentity(username, displayName string) (OwnerIdentity, error) {
+	username, usernameKey, err := NormalizeUsername(username)
+	if err != nil {
+		return OwnerIdentity{}, err
+	}
+	displayName = norm.NFC.String(strings.TrimSpace(displayName))
+	if !validIdentityText(displayName) {
+		return OwnerIdentity{}, ErrInvalidDisplayName
+	}
+	return OwnerIdentity{
+		Username:    username,
+		UsernameKey: usernameKey,
+		DisplayName: displayName,
+	}, nil
+}
+
+func NormalizeUsername(username string) (string, string, error) {
+	username = norm.NFC.String(strings.TrimSpace(username))
+	if !validIdentityText(username) {
+		return "", "", ErrInvalidUsername
+	}
+	return username, cases.Fold().String(username), nil
+}
+
+func ValidatePassword(password string) error {
+	if !utf8.ValidString(password) || len(password) > MaximumPasswordBytes || utf8.RuneCountInString(password) < MinimumPasswordRunes {
+		return ErrInvalidPassword
+	}
+	return nil
+}
+
+func validIdentityText(value string) bool {
+	count := utf8.RuneCountInString(value)
+	if count == 0 || count > MaximumIdentityRunes {
+		return false
+	}
+	for _, character := range value {
+		if unicode.IsControl(character) {
+			return false
+		}
+	}
+	return true
+}