<?php
/*
    SEHS3245 Web Systems and Technologies Project
    Otaku 網上公仔商店 - 購物車頁面和PHP後端處理
    
    作者: [學生姓名]
    學號: [學生學號]
    創建日期: 2025年11月17日
    
    檔案功能:
    - 購物車頁面顯示
    - AJAX 購物車操作處理
    - PHP Session 管理
    - 商品数量管理
    - 購物車清空功能
    
    PHP 功能:
    1. addToCart() - 添加商品到購物車
    2. updateQuantity() - 更新商品數量
    3. removeFromCart() - 移除商品
    4. clearCart() - 清空購物車
    5. calculateCartTotal() - 計算總價格
*/

// 啟動 Session：用於在伺服器端儲存購物車數據
session_start();

// 設定錯誤報告
error_reporting(E_ALL);
ini_set('display_errors', 1);

// 設定字符編碼
header('Content-Type: text/html; charset=utf-8');

// 處理 AJAX 請求
if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['action'])) {
    header('Content-Type: application/json');
    
    switch ($_POST['action']) {
        case 'add_to_cart':
            addToCart($_POST['product_id'], $_POST['product_name'], $_POST['price'], $_POST['quantity']);
            break;
        case 'update_quantity':
            updateQuantity($_POST['product_id'], $_POST['quantity']);
            break;
        case 'remove_from_cart':
            removeFromCart($_POST['product_id']);
            break;
        case 'clear_cart':
            clearCart();
            break;
        case 'get_cart':
            getCart();
            break;
    }
    exit;
}

// ===== 購物車功能函數 =====
/**
 * 添加商品到購物車
 * @param string $productId - 商品ID
 * @param string $productName - 商品名稱
 * @param float $price - 商品價格
 * @param int $quantity - 購買數量
 */
function addToCart($productId, $productName, $price, $quantity) {
    // 初始化購物車陣列（如果不存在）
    if (!isset($_SESSION['cart'])) {
        $_SESSION['cart'] = array();
    }
    
    $quantity = intval($quantity);
    $price = floatval($price);
    
    if (isset($_SESSION['cart'][$productId])) {
        $_SESSION['cart'][$productId]['quantity'] += $quantity;
    } else {
        $_SESSION['cart'][$productId] = array(
            'name' => $productName,
            'price' => $price,
            'quantity' => $quantity,
            'added_time' => time()
        );
    }
    
    echo json_encode(array('status' => 'success', 'message' => '商品已加入購物車'));
}

function updateQuantity($productId, $quantity) {
    $quantity = intval($quantity);
    
    if (isset($_SESSION['cart'][$productId])) {
        if ($quantity <= 0) {
            unset($_SESSION['cart'][$productId]);
        } else {
            $_SESSION['cart'][$productId]['quantity'] = $quantity;
        }
        echo json_encode(array('status' => 'success', 'message' => '數量已更新'));
    } else {
        echo json_encode(array('status' => 'error', 'message' => '商品不存在'));
    }
}

function removeFromCart($productId) {
    if (isset($_SESSION['cart'][$productId])) {
        unset($_SESSION['cart'][$productId]);
        echo json_encode(array('status' => 'success', 'message' => '商品已移除'));
    } else {
        echo json_encode(array('status' => 'error', 'message' => '商品不存在'));
    }
}

function clearCart() {
    $_SESSION['cart'] = array();
    echo json_encode(array('status' => 'success', 'message' => '購物車已清空'));
}

function getCart() {
    $cart = isset($_SESSION['cart']) ? $_SESSION['cart'] : array();
    $total = 0;
    $totalItems = 0;
    
    foreach ($cart as $item) {
        $total += $item['price'] * $item['quantity'];
        $totalItems += $item['quantity'];
    }
    
    echo json_encode(array(
        'status' => 'success',
        'cart' => $cart,
        'total' => $total,
        'totalItems' => $totalItems
    ));
}

// 計算購物車總計
function calculateCartTotal() {
    if (!isset($_SESSION['cart']) || empty($_SESSION['cart'])) {
        return 0;
    }
    
    $total = 0;
    foreach ($_SESSION['cart'] as $item) {
        $total += $item['price'] * $item['quantity'];
    }
    return $total;
}

// 計算購物車商品總數
function getCartItemCount() {
    if (!isset($_SESSION['cart']) || empty($_SESSION['cart'])) {
        return 0;
    }
    
    $count = 0;
    foreach ($_SESSION['cart'] as $item) {
        $count += $item['quantity'];
    }
    return $count;
}

// 獲取購物車內容用於顯示
$cartItems = isset($_SESSION['cart']) ? $_SESSION['cart'] : array();
$cartTotal = calculateCartTotal();
$cartItemCount = getCartItemCount();
?>

<!DOCTYPE html>
<html lang="zh-TW">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>購物車 - Otaku</title>
    <link rel="stylesheet" href="../css/style.css">
    <style>
        .cart-container {
            background: white;
            border-radius: 15px;
            padding: 2rem;
            box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
            margin-bottom: 2rem;
        }
        
        .cart-item {
            display: flex;
            align-items: center;
            padding: 1.5rem 0;
            border-bottom: 1px solid #eee;
        }
        
        .cart-item:last-child {
            border-bottom: none;
        }
        
        .item-info {
            flex: 1;
            margin-left: 1rem;
        }
        
        .item-name {
            font-weight: 600;
            color: #2c3e50;
            margin-bottom: 0.5rem;
        }
        
        .item-price {
            color: #e74c3c;
            font-weight: bold;
        }
        
        .quantity-controls {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            margin: 0 1rem;
        }
        
        .quantity-btn {
            background: #667eea;
            color: white;
            border: none;
            border-radius: 50%;
            width: 30px;
            height: 30px;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        
        .quantity-btn:hover {
            background: #5a67d8;
        }
        
        .remove-btn {
            background: #ff6b6b;
            color: white;
            border: none;
            padding: 0.5rem 1rem;
            border-radius: 20px;
            cursor: pointer;
            transition: all 0.3s ease;
        }
        
        .remove-btn:hover {
            background: #ff5252;
        }
        
        .cart-summary {
            text-align: right;
            padding: 2rem;
            background: #f8f9fa;
            border-radius: 10px;
            margin-top: 2rem;
        }
        
        .total-price {
            font-size: 1.5rem;
            font-weight: bold;
            color: #e74c3c;
            margin-bottom: 1rem;
        }
        
        .checkout-btn {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            padding: 15px 40px;
            border-radius: 25px;
            font-size: 1.1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
        }
        
        .checkout-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 25px rgba(102, 126, 234, 0.4);
        }
        
        .empty-cart {
            text-align: center;
            padding: 3rem;
            color: #666;
        }
        
        .empty-cart h2 {
            margin-bottom: 1rem;
            color: #2c3e50;
        }
        
        .continue-shopping {
            display: inline-block;
            margin-top: 2rem;
            padding: 12px 24px;
            background: #667eea;
            color: white;
            text-decoration: none;
            border-radius: 25px;
            transition: all 0.3s ease;
        }
        
        .continue-shopping:hover {
            background: #5a67d8;
            transform: translateY(-2px);
        }
    </style>
</head>
<body>
    <nav class="navbar">
        <div class="nav-container">
            <div class="logo">
                <!-- 網站標誌，點擊返回首頁 -->
                <a href="index.html">Otaku</a>
            </div>
            <ul class="nav-menu">
                <li><a href="../../index.html">首頁</a></li>
                <li><a href="../html/anime-figures.html">卡通動漫</a></li>
                <li><a href="../html/game-figures.html">遊戲角色</a></li>
                <li><a href="../html/limited-figures.html">限定收藏</a></li>
                <li><a href="cart.php" class="active">購物車 <span id="cart-count"><?php echo $cartItemCount; ?></span></a></li>
            </ul>
        </div>
    </nav>

    <main class="main-content">
        <div class="container">
            <div class="page-header">
                <h1>購物車</h1>
                <p>您的購物車內容</p>
            </div>

            <?php if (empty($cartItems)): ?>
                <div class="cart-container">
                    <div class="empty-cart">
                        <h2>您的購物車是空的</h2>
                        <p>快去選購您喜歡的公仔吧！</p>
                        <a href="../html/anime-figures.html" class="continue-shopping">繼續購物</a>
                    </div>
                </div>
            <?php else: ?>
                <div class="cart-container">
                    <h2>購物車商品</h2>
                    
                    <?php foreach ($cartItems as $productId => $item): ?>
                        <div class="cart-item" id="item-<?php echo htmlspecialchars($productId); ?>">
                            <div class="item-info">
                                <div class="item-name"><?php echo htmlspecialchars($item['name']); ?></div>
                                <div class="item-price">HK$<?php echo number_format($item['price']); ?></div>
                                <div class="item-subtotal">小計: HK$<?php echo number_format($item['price'] * $item['quantity']); ?></div>
                            </div>
                            
                            <div class="quantity-controls">
                                <button class="quantity-btn" onclick="updateQuantity('<?php echo $productId; ?>', <?php echo $item['quantity'] - 1; ?>)">-</button>
                                <span class="quantity"><?php echo $item['quantity']; ?></span>
                                <button class="quantity-btn" onclick="updateQuantity('<?php echo $productId; ?>', <?php echo $item['quantity'] + 1; ?>)">+</button>
                            </div>
                            
                            <button class="remove-btn" onclick="removeFromCart('<?php echo $productId; ?>')">移除</button>
                        </div>
                    <?php endforeach; ?>
                    
                    <div class="cart-summary">
                        <div class="total-price">總計: HK$<?php echo number_format($cartTotal); ?></div>
                        <button class="checkout-btn" onclick="checkout()">立即結帳</button>
                    </div>
                </div>
            <?php endif; ?>

            <div class="page-navigation">
                <a href="../html/limited-figures.html" class="nav-btn">← 繼續購物</a>
            </div>
        </div>
    </main>

    <!-- 頁腳區域：顯示版權資訊 -->
    <footer class="footer">
        <div class="container">
            <p>&copy; 2025 Otaku. 版權所有.</p>
        </div>
    </footer>

    <script src="../js/script.js"></script>
    <script>
        /**
         * 更新商品數量
         * @param {string} productId - 商品ID
         * @param {number} newQuantity - 新的數量
         */
        function updateQuantity(productId, newQuantity) {
            if (newQuantity <= 0) {
                removeFromCart(productId);
                return;
            }
            
            fetch('cart.php', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded',
                },
                body: `action=update_quantity&product_id=${productId}&quantity=${newQuantity}`
            })
            .then(response => response.json())
            .then(data => {
                if (data.status === 'success') {
                    location.reload();
                } else {
                    alert(data.message);
                }
            })
            .catch(error => {
                console.error('Error:', error);
                alert('更新失敗，請稍後再試');
            });
        }
        
        /**
         * 從購物車移除商品
         * @param {string} productId - 要移除的商品ID
         */
        function removeFromCart(productId) {
            if (confirm('確定要移除此商品嗎？')) {
                fetch('cart.php', {
                    method: 'POST',
                    headers: {
                        'Content-Type': 'application/x-www-form-urlencoded',
                    },
                    body: `action=remove_from_cart&product_id=${productId}`
                })
                .then(response => response.json())
                .then(data => {
                    if (data.status === 'success') {
                        location.reload();
                    } else {
                        alert(data.message);
                    }
                })
                .catch(error => {
                    console.error('Error:', error);
                    alert('移除失敗，請稍後再試');
                });
            }
        }
        
        /**
         * 結帳功能：跳轉到感謝頁面
         */
        function checkout() {
            // 這裡會連接到第六個頁面（感謝頁面）
            window.location.href = 'thank-you.php';
        }
    </script>
</body>
</html>