<?php
header('Content-Type: application/json');
session_start();

$servername = "localhost";
$username = "root";
$password = "root";
$dbname = "cyberpunk";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die(json_encode(['success' => false, 'message' => '连接数据库失败: ' . $conn->connect_error]));
}

// 检查用户是否已登录
if (!isset($_SESSION['id'])) {
    die(json_encode(['success' => false, 'message' => '用户未登录，请先登录。']));
}

$user_id = $_SESSION['id'];
$purchase_items = isset($_POST['purchase_items']) && is_array($_POST['purchase_items']) ? $_POST['purchase_items'] : [];
$delivery_address = isset($_POST['delivery_address']) && is_array($_POST['delivery_address']) ? $_POST['delivery_address'] : [];

// 确保所有地址字段都存在且非空
if (
    !isset($delivery_address['address_line_1']) || empty($delivery_address['address_line_1']) ||
    !isset($delivery_address['city']) || empty($delivery_address['city']) ||
    !isset($delivery_address['state_province']) || empty($delivery_address['state_province']) ||
    !isset($delivery_address['country']) || empty($delivery_address['country']) ||
    !isset($delivery_address['postal_code']) || empty($delivery_address['postal_code'])
) {
    die(json_encode(['success' => false, 'message' => '缺失或无效的送货地址信息']));
}

if (empty($purchase_items)) {
    die(json_encode(['success' => false, 'message' => '未接收到要购买的商品ID。']));
}

// 查询用户余额和商品详情
$sql = "
    SELECT u.Money, v.id AS vehicle_id, v.brand, v.price
    FROM users u
    INNER JOIN vehicle v ON v.id IN (" . implode(',', $purchase_items) . ")
    WHERE u.id = ?
";
$stmt = $conn->prepare($sql);

if (!$stmt) {
    handleQueryError($conn, "预处理查询用户余额和商品详情 SQL 语句失败");
}

$stmt->bind_param("i", $user_id);
$stmt->execute();
$result = $stmt->get_result();

$user_balance = null;
$vehicles_data = [];
while ($row = $result->fetch_assoc()) {
    if ($row['Money']) {
        $user_balance = $row['Money'];
    }
    $vehicles_data[$row['vehicle_id']] = [
        'brand' => $row['brand'],
        'price' => $row['price'],
    ];
}
$stmt->close();

if ($user_balance === null) {
    die(json_encode(['success' => false, 'message' => '用户余额查询失败。']));
}

// 计算商品总价
$total_price = array_sum(array_column($vehicles_data, 'price'));

// 判断余额是否足够
if ($user_balance < $total_price) {
    die(json_encode([
        'success' => false,
        'message' => '余额不足，无法购买所选商品。',
        'remaining_balance' => $user_balance,
    ]));
}

// 扣除用户余额（假设交易成功）
$new_balance = $user_balance - $total_price;
$sql = "UPDATE users SET Money = ? WHERE id = ?";
$stmt = $conn->prepare($sql);

if (!$stmt) {
    handleQueryError($conn, "预处理更新用户余额 SQL 语句失败");
}

$stmt->bind_param("di", $new_balance, $user_id);
$stmt->execute();
$affected_rows = $stmt->affected_rows;
$stmt->close();

if ($affected_rows > 0) {
    // 删除购物车中的商品
    $sql = "DELETE FROM user_cart WHERE user_id = ? AND vehicle_id IN (?)";
    $stmt = $conn->prepare($sql);

    if (!$stmt) {
        handleQueryError($conn, "预处理删除购物车商品 SQL 语句失败");
    }

    $stmt->bind_param("is", $user_id, implode(',', $purchase_items));
    $stmt->execute();
    $affected_rows = $stmt->affected_rows;

    if ($affected_rows > 0) {
        // 插入购买记录到 purchase_records 表
        $sql = "INSERT INTO purchase_records (user_id, vehicle_id, purchase_date) VALUES (?, ?, NOW())";
        $stmt = $conn->prepare($sql);

        if (!$stmt) {
            handleQueryError($conn, "预处理插入购买记录 SQL 语句失败");
        }

        foreach ($purchase_items as $vehicle_id) {
            $stmt->bind_param("ii", $user_id, $vehicle_id);
            $stmt->execute();
        }

        // 插入订单数据到 orders 表
        $sql = "INSERT INTO orders (user_id, vehicle_id, brand, price, purchase_date, address_line_1, city, state_province, country, postal_code) VALUES (?, ?, ?, ?, NOW(), ?, ?, ?, ?, ?)";
        $stmt = $conn->prepare($sql);

        if (!$stmt) {
            handleQueryError($conn, "预处理插入订单数据 SQL 语句失败");
        }

        $insertion_errors = [];  // 存储插入订单时的错误信息

        foreach ($purchase_items as $vehicle_id) {
            $vehicle_data = $vehicles_data[$vehicle_id];
            $stmt->bind_param(
                "iisssssss",
                $user_id,
                $vehicle_id,
                $vehicle_data['brand'],
                $vehicle_data['price'],
                $delivery_address['address_line_1'],
                $delivery_address['city'],
                $delivery_address['state_province'],
                $delivery_address['country'],
                $delivery_address['postal_code']
            );

            if (!$stmt->execute()) {
                $insertion_errors[] = [
                    'vehicle_id' => $vehicle_id,
                    'error' => $stmt->error,
                ];
            }
        }

        $stmt->close();

        if (!empty($insertion_errors)) {
            $error_messages = array_map(function ($error) {
                return "订单插入失败 (车辆ID: {$error['vehicle_id']}): {$error['error']}";
            }, $insertion_errors);

            die(json_encode([
                'success' => false,
                'message' => '部分订单插入失败: ' . implode('; ', $error_messages),
                'remaining_balance' => $new_balance,
            ]));
        }

        $response = [
            'success' => true,
            'message' => '购买成功，车辆已发车至您的车库中！',
            'remaining_balance' => $new_balance,
        ];
    } else {
        $response = [
            'success' => false,
            'message' => '删除购物车商品时发生错误。',
            'remaining_balance' => $new_balance,
        ];
    }
} else {
    $response = [
        'success' => false,
        'message' => '更新用户余额时发生错误，请稍后再试。',
        'remaining_balance' => $user_balance,
    ];
}

// 输出 JSON 数据
echo json_encode($response);

$conn->close();

function handleQueryError(mysqli $conn, string $error_message): void
{
    $conn_error = $conn->error;
    die(json_encode([
        'success' => false,
        'message' => "$error_message: $conn_error",
    ]));
}