/**
 * Royal Red Bull - Cart Logic Manager
 * Handles persistent storage between index.html and cart.html
 */

// 1. Initialize cart by pulling from LocalStorage (browser memory)
// If nothing is saved, start with an empty array []
let cart = JSON.parse(localStorage.getItem('cart_data')) || [];

/**
 * Adds a product to the cart and saves it to memory
 * @param {Object} product - The product object from products.js
 */
function addToCart(product) {
    // Check if the item already exists in the cart using its ID
    const existingItem = cart.find(item => item.id === product.id);
    
    if (existingItem) {
        // If it exists, increase the quantity count
        existingItem.quantity = (existingItem.quantity || 1) + 1;
    } else {
        // If it's a new item, add it to the list with quantity 1
        cart.push({ 
            ...product, 
            quantity: 1 
        });
    }
    
    // Save the updated list to the browser's LocalStorage
    saveCart();
}

/**
 * Saves the current cart array to LocalStorage as a string
 */
function saveCart() {
    localStorage.setItem('cart_data', JSON.stringify(cart));
}

/**
 * Calculates the total number of items currently in the cart
 * @returns {number} Total quantity
 */
function getCartCount() {
    return cart.reduce((total, item) => total + (item.quantity || 1), 0);
}

/**
 * Clears the entire cart (Optional helper)
 */
function clearCart() {
    cart = [];
    localStorage.removeItem('cart_data');
}