const Cart = (function () {
	const STORAGE_KEY = "cart";
	const TAX_RATE = 0.05;
	let couponDiscount = 0;

	// ─────────────────────────────
	// Internal
	// ─────────────────────────────
	function getCart() {
		return JSON.parse(localStorage.getItem(STORAGE_KEY)) || [];
	}

	function saveCart(cart) {
		localStorage.setItem(STORAGE_KEY, JSON.stringify(cart));
		window.dispatchEvent(new Event("cartUpdated"));
	}

	function findItem(cart, id) {
		return cart.find((item) => item.id === id);
	}

	// ─────────────────────────────
	// Public API
	// ─────────────────────────────

	function addItem(product, quantity = 1) {
		const cart = getCart();
		const existing = findItem(cart, product.id);

		if (existing) {
			existing.quantity += quantity;
		} else {
			cart.push({
				id: product.id,
				name: product.basic.name,
				price: product.pricing.price,
				image: product.media.mainImage,
				quantity,
			});
		}

		saveCart(cart);
	}

	function removeItem(id) {
		const cart = getCart().filter((item) => item.id !== id);
		saveCart(cart);
	}

	function updateQuantity(id, quantity) {
		const cart = getCart();
		const item = findItem(cart, id);
		if (!item) return;

		item.quantity = Math.max(1, quantity);
		saveCart(cart);
	}

	function clear() {
		localStorage.removeItem(STORAGE_KEY);
		window.dispatchEvent(new Event("cartUpdated"));
	}

	function applyCoupon(code) {
		if (code === "MEDI10") {
			couponDiscount = 0.1;
			window.dispatchEvent(new Event("cartUpdated"));
			return true;
		}

		couponDiscount = 0;
		window.dispatchEvent(new Event("cartUpdated"));
		return false;
	}

	function getTotals() {
		const cart = getCart();

		const subtotal = cart.reduce(
			(sum, item) => sum + item.price * item.quantity,
			0
		);

		const tax = subtotal * TAX_RATE;
		const discount = subtotal * couponDiscount;
		const total = subtotal - discount;

		return {
			subtotal,
			tax,
			discount,
			total,
		};
	}

	function getTotalCount() {
		return getCart().reduce((sum, item) => sum + item.quantity, 0);
	}

	return {
		getCart,
		addItem,
		removeItem,
		updateQuantity,
		clear,
		applyCoupon,
		getTotals,
		getTotalCount,
	};
})();