E-Commerce Shopping Cart System

import java.util.*;

class Product {
    private String productId;
    private String name;
    private String category;
    private double price;
    private int stock;
    
    public Product(String productId, String name, String category, double price, int stock) {
        this.productId = productId;
        this.name = name;
        this.category = category;
        this.price = price;
        this.stock = stock;
    }
    
    public String getProductId() { return productId; }
    public String getName() { return name; }
    public String getCategory() { return category; }
    public double getPrice() { return price; }
    public int getStock() { return stock; }
    
    public boolean reduceStock(int quantity) {
        if (stock >= quantity) {
            stock -= quantity;
            return true;
        }
        return false;
    }
    
    public void addStock(int quantity) {
        stock += quantity;
    }
    
    public void displayProduct() {
        System.out.printf("%-10s %-30s %-15s ₹%8.2f Stock: %d\n",
            productId, name, category, price, stock);
    }
}

class CartItem {
    private Product product;
    private int quantity;
    
    public CartItem(Product product, int quantity) {
        this.product = product;
        this.quantity = quantity;
    }
    
    public Product getProduct() { return product; }
    public int getQuantity() { return quantity; }
    
    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
    
    public void incrementQuantity(int amount) {
        this.quantity += amount;
    }
    
    public double getSubtotal() {
        return product.getPrice() * quantity;
    }
}

class Coupon {
    private String code;
    private double discountPercentage;
    private double minPurchase;
    private boolean isActive;
    
    public Coupon(String code, double discountPercentage, double minPurchase) {
        this.code = code;
        this.discountPercentage = discountPercentage;
        this.minPurchase = minPurchase;
        this.isActive = true;
    }
    
    public String getCode() { return code; }
    public double getDiscountPercentage() { return discountPercentage; }
    public double getMinPurchase() { return minPurchase; }
    public boolean isActive() { return isActive; }
    
    public boolean isApplicable(double cartTotal) {
        return isActive && cartTotal >= minPurchase;
    }
}

class ShoppingCart {
    private HashMap<String, CartItem> items;
    private Coupon appliedCoupon;
    
    public ShoppingCart() {
        items = new HashMap<>();
        appliedCoupon = null;
    }
    
    public void addItem(Product product, int quantity) {
        if (!product.reduceStock(quantity)) {
            System.out.println("✗ Insufficient stock! Available: " + product.getStock());
            return;
        }
        
        CartItem existing = items.get(product.getProductId());
        if (existing != null) {
            existing.incrementQuantity(quantity);
            System.out.println("✓ Updated quantity for " + product.getName());
        } else {
            items.put(product.getProductId(), new CartItem(product, quantity));
            System.out.println("✓ Added " + product.getName() + " to cart");
        }
    }
    
    public void removeItem(String productId) {
        CartItem item = items.remove(productId);
        if (item != null) {
            item.getProduct().addStock(item.getQuantity());
            System.out.println("✓ Removed from cart");
        } else {
            System.out.println("✗ Item not in cart");
        }
    }
    
    public void updateQuantity(String productId, int newQuantity) {
        CartItem item = items.get(productId);
        if (item == null) {
            System.out.println("✗ Item not in cart");
            return;
        }
        
        int difference = newQuantity - item.getQuantity();
        if (difference > 0) {
            if (!item.getProduct().reduceStock(difference)) {
                System.out.println("✗ Insufficient stock!");
                return;
            }
        } else if (difference < 0) {
            item.getProduct().addStock(-difference);
        }
        
        item.setQuantity(newQuantity);
        System.out.println("✓ Quantity updated");
    }
    
    public double getSubtotal() {
        double total = 0;
        for (CartItem item : items.values()) {
            total += item.getSubtotal();
        }
        return total;
    }
    
    public boolean applyCoupon(Coupon coupon) {
        double subtotal = getSubtotal();
        if (coupon.isApplicable(subtotal)) {
            appliedCoupon = coupon;
            System.out.println("✓ Coupon " + coupon.getCode() + " applied!");
            return true;
        } else {
            System.out.printf("✗ Minimum purchase of ₹%.2f required\n", coupon.getMinPurchase());
            return false;
        }
    }
    
    public double getDiscount() {
        if (appliedCoupon == null) return 0;
        return getSubtotal() * appliedCoupon.getDiscountPercentage() / 100;
    }
    
    public double getTotal() {
        return getSubtotal() - getDiscount();
    }
    
    public void displayCart() {
        if (items.isEmpty()) {
            System.out.println("\n🛒 Your cart is empty");
            return;
        }
        
        System.out.println("\n╔══════════════════════════════════════════════════════════════╗");
        System.out.println("║                    YOUR SHOPPING CART                        ║");
        System.out.println("╚══════════════════════════════════════════════════════════════╝");
        
        System.out.printf("\n%-10s %-30s %-8s %-10s %-10s\n",
            "ID", "Product", "Price", "Qty", "Subtotal");
        System.out.println("─".repeat(70));
        
        for (CartItem item : items.values()) {
            Product product = item.getProduct();
            System.out.printf("%-10s %-30s ₹%8.2f %-10d ₹%10.2f\n",
                product.getProductId(), product.getName(), product.getPrice(),
                item.getQuantity(), item.getSubtotal());
        }
        
        System.out.println("─".repeat(70));
        System.out.printf("%-60s ₹%10.2f\n", "Subtotal:", getSubtotal());
        
        if (appliedCoupon != null) {
            System.out.printf("%-60s -₹%10.2f\n",
                "Discount (" + appliedCoupon.getCode() + " " +
                appliedCoupon.getDiscountPercentage() + "%):", getDiscount());
        }
        
        System.out.println("═".repeat(70));
        System.out.printf("%-60s ₹%10.2f\n", "TOTAL:", getTotal());
        System.out.println("═".repeat(70));
    }
    
    public void checkout() {
        if (items.isEmpty()) {
            System.out.println("✗ Cart is empty!");
            return;
        }
        
        System.out.println("\n╔══════════════════════════════════════════════════════════════╗");
        System.out.println("║                    ORDER INVOICE                             ║");
        System.out.println("╚══════════════════════════════════════════════════════════════╝");
        System.out.println("Order Date: " + new Date());
        System.out.println("Order ID: ORD" + System.currentTimeMillis());
        
        displayCart();
        
        System.out.println("\n✓ Order placed successfully!");
        System.out.println("Thank you for shopping with us!");
        
        items.clear();
        appliedCoupon = null;
    }
    
    public boolean isEmpty() {
        return items.isEmpty();
    }
}

class Store {
    private HashMap<String, Product> catalog;
    private HashMap<String, Coupon> coupons;
    
    public Store() {
        catalog = new HashMap<>();
        coupons = new HashMap<>();
        loadSampleData();
    }
    
    private void loadSampleData() {
        addProduct(new Product("ELEC001", "Laptop", "Electronics", 45000, 10));
        addProduct(new Product("ELEC002", "Smartphone", "Electronics", 15000, 25));
        addProduct(new Product("ELEC003", "Headphones", "Electronics", 2000, 50));
        addProduct(new Product("BOOK001", "Java Programming", "Books", 500, 100));
        addProduct(new Product("FASH001", "T-Shirt", "Fashion", 300, 200));
        
        addCoupon(new Coupon("SAVE10", 10, 1000));
        addCoupon(new Coupon("SAVE20", 20, 5000));
        addCoupon(new Coupon("MEGA50", 50, 20000));
    }
    
    public void addProduct(Product product) {
        catalog.put(product.getProductId(), product);
    }
    
    public void addCoupon(Coupon coupon) {
        coupons.put(coupon.getCode(), coupon);
    }
    
    public Product getProduct(String productId) {
        return catalog.get(productId);
    }
    
    public Coupon getCoupon(String code) {
        return coupons.get(code.toUpperCase());
    }
    
    public void displayCatalog() {
        System.out.println("\n╔══════════════════════════════════════════════════════════════╗");
        System.out.println("║                    PRODUCT CATALOG                           ║");
        System.out.println("╚══════════════════════════════════════════════════════════════╝\n");
        
        System.out.printf("%-10s %-30s %-15s %-10s %-8s\n",
            "ID", "Name", "Category", "Price", "Stock");
        System.out.println("─".repeat(80));
        
        for (Product product : catalog.values()) {
            product.displayProduct();
        }
    }
    
    public void displayCoupons() {
        System.out.println("\n╔══════════════════════════════════════════════════════════════╗");
        System.out.println("║                    AVAILABLE COUPONS                         ║");
        System.out.println("╚══════════════════════════════════════════════════════════════╝\n");
        
        for (Coupon coupon : coupons.values()) {
            System.out.printf("Code: %-10s | %d%% OFF | Min Purchase: ₹%.2f\n",
                coupon.getCode(), (int)coupon.getDiscountPercentage(), coupon.getMinPurchase());
        }
    }
}

public class ECommerceShoppingCart {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Store store = new Store();
        ShoppingCart cart = new ShoppingCart();
        
        System.out.println("╔═══════════════════════════════════════════════╗");
        System.out.println("║        WELCOME TO ONLINE STORE                ║");
        System.out.println("╚═══════════════════════════════════════════════╝\n");
        
        boolean running = true;
        
        while (running) {
            System.out.println("\n" + "═".repeat(50));
            System.out.println("              SHOPPING MENU");
            System.out.println("═".repeat(50));
            System.out.println("  1. Browse Products");
            System.out.println("  2. Add to Cart");
            System.out.println("  3. View Cart");
            System.out.println("  4. Update Quantity");
            System.out.println("  5. Remove from Cart");
            System.out.println("  6. Apply Coupon");
            System.out.println("  7. View Coupons");
            System.out.println("  8. Checkout");
            System.out.println("  0. Exit");
            System.out.println("═".repeat(50));
            System.out.print("Enter choice: ");
            
            int choice = scanner.nextInt();
            scanner.nextLine();
            
            switch (choice) {
                case 1:
                    store.displayCatalog();
                    break;
                    
                case 2:
                    store.displayCatalog();
                    System.out.print("\nEnter Product ID: ");
                    String pid = scanner.nextLine();
                    Product product = store.getProduct(pid);
                    if (product != null) {
                        System.out.print("Enter quantity: ");
                        int qty = scanner.nextInt();
                        cart.addItem(product, qty);
                    } else {
                        System.out.println("✗ Product not found!");
                    }
                    break;
                    
                case 3:
                    cart.displayCart();
                    break;
                    
                case 4:
                    System.out.print("\nEnter Product ID: ");
                    String pid2 = scanner.nextLine();
                    System.out.print("Enter new quantity: ");
                    int newQty = scanner.nextInt();
                    cart.updateQuantity(pid2, newQty);
                    break;
                    
                case 5:
                    System.out.print("\nEnter Product ID to remove: ");
                    String pid3 = scanner.nextLine();
                    cart.removeItem(pid3);
                    break;
                    
                case 6:
                    store.displayCoupons();
                    System.out.print("\nEnter Coupon Code: ");
                    String code = scanner.nextLine();
                    Coupon coupon = store.getCoupon(code);
                    if (coupon != null) {
                        cart.applyCoupon(coupon);
                    } else {
                        System.out.println("✗ Invalid coupon code!");
                    }
                    break;
                    
                case 7:
                    store.displayCoupons();
                    break;
                    
                case 8:
                    cart.checkout();
                    break;
                    
                case 0:
                    System.out.println("\n╔═══════════════════════════════════════════╗");
                    System.out.println("║   Thank you for shopping with us!         ║");
                    System.out.println("╚═══════════════════════════════════════════╝\n");
                    running = false;
                    break;
                    
                default:
                    System.out.println("\n✗ Invalid choice!");
            }
        }
        
        scanner.close();
    }
}