Local file storage (#5763)

Co-authored-by: Tom Moor <tom.moor@gmail.com>

server/validation.ts

@@ -1,6 +1,8 @@
 import isArrayLike from "lodash/isArrayLike";
+import sanitize from "sanitize-filename";
 import { Primitive } from "utility-types";
 import validator from "validator";
+import isIn from "validator/lib/isIn";
 import isUUID from "validator/lib/isUUID";
 import parseMentionUrl from "@shared/utils/parseMentionUrl";
 import { SLUG_URL_REGEX } from "@shared/utils/urlHelpers";
@@ -170,6 +172,30 @@ export const assertCollectionPermission = (
   assertIn(value, [...Object.values(CollectionPermission), null], message);
 };
 
+export class ValidateKey {
+  public static isValid = (key: string) => {
+    const parts = key.split("/").slice(0, -1);
+    return (
+      parts.length === 3 &&
+      isIn(parts[0], ["uploads", "public"]) &&
+      isUUID(parts[1]) &&
+      isUUID(parts[2])
+    );
+  };
+
+  public static sanitize = (key: string) => {
+    const [filename] = key.split("/").slice(-1);
+    return key
+      .split("/")
+      .slice(0, -1)
+      .join("/")
+      .concat(`/${sanitize(filename)}`);
+  };
+
+  public static message =
+    "Must be of the form uploads/<uuid>/<uuid>/<name> or public/<uuid>/<uuid>/<name>";
+}
+
 export class ValidateDocumentId {
   /**
    * Checks if documentId is valid. A valid documentId is either