1 files changed, 45 insertions, 0 deletions
diff --git a/apps/files_sharing/src/services/GuestNameValidity.ts b/apps/files_sharing/src/services/GuestNameValidity.ts
new file mode 100644
index 00000000000..0557c5253ca
--- /dev/null
+++ b/apps/files_sharing/src/services/GuestNameValidity.ts
@@ -0,0 +1,45 @@
+/*!
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+import { InvalidFilenameError, InvalidFilenameErrorReason, validateFilename } from '@nextcloud/files'
+import { t } from '@nextcloud/l10n'
+
+/**
+ * Get the validity of a filename (empty if valid).
+ * This can be used for `setCustomValidity` on input elements
+ * @param name The filename
+ * @param escape Escape the matched string in the error (only set when used in HTML)
+ */
+export function getGuestNameValidity(name: string, escape = false): string {
+	if (name.trim() === '') {
+		return t('files', 'Names must not be empty.')
+	}
+
+	if (name.startsWith('.')) {
+		return t('files', 'Names must not start with a dot.')
+	}
+
+	try {
+		validateFilename(name)
+		return ''
+	} catch (error) {
+		if (!(error instanceof InvalidFilenameError)) {
+			throw error
+		}
+
+		switch (error.reason) {
+		case InvalidFilenameErrorReason.Character:
+			return t('files', '"{char}" is not allowed inside a name.', { char: error.segment }, undefined, { escape })
+		case InvalidFilenameErrorReason.ReservedName:
+			return t('files', '"{segment}" is a reserved name and not allowed.', { segment: error.segment }, undefined, { escape: false })
+		case InvalidFilenameErrorReason.Extension:
+			if (error.segment.match(/\.[a-z]/i)) {
+				return t('files', '"{extension}" is not an allowed name.', { extension: error.segment }, undefined, { escape: false })
+			}
+			return t('files', 'Names must not end with "{extension}".', { extension: error.segment }, undefined, { escape: false })
+		default:
+			return t('files', 'Invalid name.')
+		}
+	}
+}