1 files changed, 17 insertions, 0 deletions
diff --git a/src/tools/chmod-calculator/chmod-calculator.service.ts b/src/tools/chmod-calculator/chmod-calculator.service.ts
new file mode 100644
index 0000000..8953551
--- /dev/null
+++ b/src/tools/chmod-calculator/chmod-calculator.service.ts
@@ -0,0 +1,17 @@
+import _ from 'lodash';
+import type { GroupPermissions, Permissions } from './chmod-calculator.types';
+
+export { computeChmodOctalRepresentation };
+
+function computeChmodOctalRepresentation({ permissions }: { permissions: Permissions }): string {
+  const permissionValue = { read: 4, write: 2, execute: 1 };
+
+  const getGroupPermissionValue = (permission: GroupPermissions) =>
+    _.reduce(permission, (acc, isPermSet, key) => acc + (isPermSet ? _.get(permissionValue, key, 0) : 0), 0);
+
+  return [
+    getGroupPermissionValue(permissions.owner),
+    getGroupPermissionValue(permissions.group),
+    getGroupPermissionValue(permissions.public),
+  ].join('');
+}