<?php
session_start();
require_once 'db/config.php';

// Check if user is logged in, if not, redirect to login page
if (!isset($_SESSION['user_id'])) {
    // For now, we'll use a hardcoded user_id for simplicity.
    // In a real application, you would redirect to a login page.
    $_SESSION['user_id'] = 1; // Hardcoded user_id for demonstration
}

$user_id = $_SESSION['user_id'];
$action = $_POST['action'] ?? '';

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    if ($action === 'add') {
        $menu_item_id = $_POST['menu_item_id'] ?? null;
        $quantity = $_POST['quantity'] ?? 1;

        if ($menu_item_id) {
            try {
                $pdo = db();
                
                // Check if the item is already in the cart
                $stmt = $pdo->prepare("SELECT * FROM cart WHERE user_id = ? AND menu_item_id = ?");
                $stmt->execute([$user_id, $menu_item_id]);
                $existing_item = $stmt->fetch();

                if ($existing_item) {
                    // If item exists, update the quantity
                    $new_quantity = $existing_item['quantity'] + $quantity;
                    $update_stmt = $pdo->prepare("UPDATE cart SET quantity = ? WHERE id = ?");
                    $update_stmt->execute([$new_quantity, $existing_item['id']]);
                } else {
                    // If item does not exist, insert it
                    $insert_stmt = $pdo->prepare("INSERT INTO cart (user_id, menu_item_id, quantity) VALUES (?, ?, ?)");
                    $insert_stmt->execute([$user_id, $menu_item_id, $quantity]);
                }

                echo json_encode(['success' => true, 'message' => 'Item added to cart.']);

            } catch (PDOException $e) {
                http_response_code(500);
                echo json_encode(['success' => false, 'message' => 'Database error: ' . $e->getMessage()]);
            }
        } else {
            http_response_code(400);
            echo json_encode(['success' => false, 'message' => 'Menu item ID is required.']);
        }
    }
}
?>