refactor: move spa to frontend folder

frontend/spa/src/ShoppingCart.js

@@ -0,0 +1,63 @@
+import {reactive} from "vue";
+
+class ShoppingCart {
+    constructor() {
+        this.items = reactive([]);
+        this.storageKey = 'shoppingCart';
+        this.storage = Telegram.WebApp.DeviceStorage;
+
+        this._load()
+            .then(items => {
+                this.items = items;
+                console.log(items);
+            })
+            .catch(error => console.log(error));
+    }
+
+    async addItem(productId, productName, quantity, options = {}) {
+        this.items.push({ productId: productId, productName: productName, quantity, options });
+        this._save(this.items);
+    }
+
+    has(productId) {
+        const item = this.getItem(productId);
+        console.log(item);
+        return this.getItem(productId) !== null;
+    }
+
+    getItem(productId) {
+        return this.items.find(item => item.productId === productId) ?? null;
+    }
+
+    getItems() {
+        return this.items;
+    }
+
+    clear() {
+        this.storage.deleteItem(this.storageKey)
+    }
+
+    async _load() {
+        return new Promise((resolve, reject) => {
+            this.storage.getItem(this.storageKey, (error, value) => {
+                if (error) {
+                    console.error(error);
+                    reject([]);
+                }
+
+                try {
+                    resolve(value ? JSON.parse(value) : []);
+                } catch (error) {
+                    console.error(error);
+                    reject([]);
+                }
+            });
+        });
+    }
+
+    _save(items) {
+        this.storage.setItem(this.storageKey, JSON.stringify(items));
+    }
+}
+
+export default ShoppingCart;