add storageModel methods

src/Model/storageModel.ts

@@ -1 +1,28 @@
-// this file is responsible for reading and writing persistent data; all storage shall be handled by this file.
+// this file is responsible for reading and writing persistent data; all storage shall be handled by this file.
+
+import { parse, stringify } from "../utility";
+
+// basic
+export function store(key: string, value: string): void {
+  localStorage.setItem(key, value);
+}
+
+export function restore(key: string): string | null {
+  return localStorage.getItem(key);
+}
+
+// array
+export function storeArray(key: string, value: any[]): void {
+    const valueString = stringify(value);
+    store(key, valueString);
+}
+
+export function restoreArray(key: string): any[] | null {
+    const valueString = restore(key);
+    if (!valueString) return null;
+    
+    const parsed = parse(valueString);
+    if (!Array.isArray(parsed)) return null;
+
+    return parsed;
+}