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diff --git a/apps/files_sharing/src/lib/SharePermissionsToolBox.js b/apps/files_sharing/src/lib/SharePermissionsToolBox.js
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+++ b/apps/files_sharing/src/lib/SharePermissionsToolBox.js
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+/**
+ * @copyright 2022 Louis Chmn <louis@chmn.me>
+ *
+ * @author Louis Chmn <louis@chmn.me>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+export const ATOMIC_PERMISSIONS = {
+	NONE: 0,
+	READ: 1,
+	UPDATE: 2,
+	CREATE: 4,
+	DELETE: 8,
+	SHARE: 16,
+}
+
+export const BUNDLED_PERMISSIONS = {
+	READ_ONLY: ATOMIC_PERMISSIONS.READ,
+	UPLOAD_AND_UPDATE: ATOMIC_PERMISSIONS.READ | ATOMIC_PERMISSIONS.UPDATE | ATOMIC_PERMISSIONS.CREATE | ATOMIC_PERMISSIONS.DELETE,
+	FILE_DROP: ATOMIC_PERMISSIONS.CREATE,
+	ALL: ATOMIC_PERMISSIONS.UPDATE | ATOMIC_PERMISSIONS.CREATE | ATOMIC_PERMISSIONS.READ | ATOMIC_PERMISSIONS.DELETE | ATOMIC_PERMISSIONS.SHARE,
+}
+
+/**
+ * Return whether a given permissions set contains some permissions.
+ *
+ * @param {number} initialPermissionSet - the permissions set.
+ * @param {number} permissionsToCheck - the permissions to check.
+ * @return {boolean}
+ */
+export function hasPermissions(initialPermissionSet, permissionsToCheck) {
+	return initialPermissionSet !== ATOMIC_PERMISSIONS.NONE && (initialPermissionSet & permissionsToCheck) === permissionsToCheck
+}
+
+/**
+ * Return whether a given permissions set is valid.
+ *
+ * @param {number} permissionsSet - the permissions set.
+ *
+ * @return {boolean}
+ */
+export function permissionsSetIsValid(permissionsSet) {
+	// Must have at least READ or CREATE permission.
+	if (!hasPermissions(permissionsSet, ATOMIC_PERMISSIONS.READ) && !hasPermissions(permissionsSet, ATOMIC_PERMISSIONS.CREATE)) {
+		return false
+	}
+
+	// Must have READ permission if have UPDATE or DELETE.
+	if (!hasPermissions(permissionsSet, ATOMIC_PERMISSIONS.READ) && (
+		hasPermissions(permissionsSet, ATOMIC_PERMISSIONS.UPDATE) || hasPermissions(permissionsSet, ATOMIC_PERMISSIONS.DELETE)
+	)) {
+		return false
+	}
+
+	return true
+}
+
+/**
+ * Add some permissions to an initial set of permissions.
+ *
+ * @param {number} initialPermissionSet - the initial permissions.
+ * @param {number} permissionsToAdd - the permissions to add.
+ *
+ * @return {number}
+ */
+export function addPermissions(initialPermissionSet, permissionsToAdd) {
+	return initialPermissionSet | permissionsToAdd
+}
+
+/**
+ * Remove some permissions from an initial set of permissions.
+ *
+ * @param {number} initialPermissionSet - the initial permissions.
+ * @param {number} permissionsToSubtract - the permissions to remove.
+ *
+ * @return {number}
+ */
+export function subtractPermissions(initialPermissionSet, permissionsToSubtract) {
+	return initialPermissionSet & ~permissionsToSubtract
+}
+
+/**
+ * Toggle some permissions from  an initial set of permissions.
+ *
+ * @param {number} initialPermissionSet - the permissions set.
+ * @param {number} permissionsToToggle - the permissions to toggle.
+ *
+ * @return {number}
+ */
+export function togglePermissions(initialPermissionSet, permissionsToToggle) {
+	if (hasPermissions(initialPermissionSet, permissionsToToggle)) {
+		return subtractPermissions(initialPermissionSet, permissionsToToggle)
+	} else {
+		return addPermissions(initialPermissionSet, permissionsToToggle)
+	}
+}
+
+/**
+ * Return whether some given permissions can be toggled from a permission set.
+ *
+ * @param {number} permissionSet - the initial permissions set.
+ * @param {number} permissionsToToggle - the permissions to toggle.
+ *
+ * @return {boolean}
+ */
+export function canTogglePermissions(permissionSet, permissionsToToggle) {
+	return permissionsSetIsValid(togglePermissions(permissionSet, permissionsToToggle))
+}