<?php
/**
 * @package AKSRT
 */

namespace AKSRT\Payment;

defined('ABSPATH') || exit;

/**
 * 支付网关管理器（注册/回调路由/到账）。
 */

class Gateway {

    private static $instance = null;
    private $gateways = [];

    public static function get_instance(): self {
        if (null === self::$instance) self::$instance = new self();
        return self::$instance;
    }

    /**
     * 注册网关
     */
    public function register(string $id, GatewayInterface $gateway): void {
        $this->gateways[$id] = $gateway;
    }

    /**
     * 获取网关
     */
    public function get_gateway(string $id): ?GatewayInterface {
        return $this->gateways[$id] ?? null;
    }

    /**
     * 获取所有已注册网关
     *
     * @return GatewayInterface[]
     */
    public function get_all(): array {
        return $this->gateways;
    }

    /**
     * 获取可用网关列表（已配置的）
     */
    public function get_available(): array {
        $available = [];
        foreach ($this->gateways as $id => $gateway) {
            if ($gateway->is_configured()) {
                $available[$id] = $gateway;
            }
        }
        return $available;
    }

    /**
     * 获取网关状态摘要（用于后台展示）
     */
    public function get_status_summary(): array {
        $summary = [];
        foreach ($this->gateways as $id => $gateway) {
            $summary[] = [
                'id'          => $id,
                'name'        => $gateway->get_name(),
                'configured'  => $gateway->is_configured(),
                'available'   => $gateway->is_configured(),
            ];
        }
        return $summary;
    }

    /**
     * 绑定支付回调路由。必须在 functions.php 中初始化。
     *
     * 此前网关 create_payment() 把 notify_url/return_url 指向
     * /wp-json/aksrt/v1/payment/{gateway}/{notify|return|cancel}，但这些路由
     * 从未注册，导致所有跳转型网关（支付宝/微信/PayPal/Stripe）无法完成支付。
     */
    public function init(): void {
        add_action('rest_api_init', [$this, 'register_routes']);
    }

    public function register_routes(): void {
        $args = [
            'methods'             => ['GET', 'POST'],
            'permission_callback' => '__return_true', // 真实性由各网关签名校验保证
            'args'                => [
                'gateway' => ['sanitize_callback' => 'sanitize_key'],
            ],
        ];

        register_rest_route('aksrt/v1', '/payment/(?P<gateway>[a-z0-9_]+)/notify', array_merge($args, [
            'callback' => [$this, 'handle_notify'],
        ]));
        register_rest_route('aksrt/v1', '/payment/(?P<gateway>[a-z0-9_]+)/return', array_merge($args, [
            'callback' => [$this, 'handle_return'],
        ]));
        register_rest_route('aksrt/v1', '/payment/(?P<gateway>[a-z0-9_]+)/cancel', array_merge($args, [
            'callback' => [$this, 'handle_cancel'],
        ]));
    }

    /**
     * 异步通知（服务器到服务器）。验签 → 到账 → 输出网关期望的 ACK。
     */
    public function handle_notify(\WP_REST_Request $request) {
        $gateway_id = sanitize_key((string) $request->get_param('gateway'));
        $gateway = $this->get_gateway($gateway_id);
        if (!$gateway) {
            return new \WP_REST_Response('gateway not found', 404);
        }

        $verify    = $gateway->verify_callback($request);
        $verified  = !empty($verify['success']);
        $paid      = $verified && ($verify['status'] ?? '') === 'paid';
        $processed = $verified;

        if ($paid) {
            // Only ACK paid notifications after the order was actually synchronized.
            $processed = $this->complete_order($gateway_id, $verify);
        }

        // 网关各自要求的 ACK 格式
        if ($gateway_id === 'wechatpay' && method_exists($gateway, 'output_callback_response')) {
            $gateway->output_callback_response(['success' => $processed]); // exit
        }
        if ($gateway_id === 'alipay' || str_starts_with($gateway_id, 'epay')) {
            // 支付宝 / 易支付异步通知要求返回纯文本 success，否则会重复通知
            if (method_exists($gateway, 'output_callback_response')) {
                $gateway->output_callback_response(['success' => $processed]); // exit
            }
            header('Content-Type: text/plain; charset=utf-8');
            echo $processed ? 'success' : 'fail';
            exit;
        }

        // Stripe / PayPal webhook：200 表示已接收；处理失败返回 400 触发重试
        return new \WP_REST_Response(['received' => $processed], $processed ? 200 : 400);
    }

    /**
     * 用户浏览器同步返回。尽力确认到账（兜底异步通知延迟），再跳回订单中心。
     */
    public function handle_return(\WP_REST_Request $request) {
        $gateway_id = sanitize_key((string) $request->get_param('gateway'));
        // Providers echo back whatever number we submitted, which for a re-pay is an
        // attempt-suffixed out_trade_no. Map it to the local order for query + redirect.
        $provider_ref = sanitize_text_field((string) ($request->get_param('order')
            ?: $request->get_param('out_trade_no')
            ?: ''));
        $order_number = $this->local_order_number($provider_ref);
        $gateway = $this->get_gateway($gateway_id);
        $status  = 'pending';

        if ($gateway) {
            if ($gateway_id === 'alipay' || str_starts_with($gateway_id, 'epay')) {
                // 支付宝 / 易支付同步返回带签名参数，可直接验签作为到账兜底
                $verify = $gateway->verify_callback($request);
                if (!empty($verify['success'])) {
                    if ($order_number === '') {
                        $order_number = $this->local_order_number(
                            sanitize_text_field((string) ($verify['order_number'] ?? ''))
                        );
                    }
                    if (($verify['status'] ?? '') === 'paid' && $this->complete_order($gateway_id, $verify)) {
                        $status = 'success';
                    } elseif ($order_number !== '') {
                        // Synchronous returns generally omit trade_status; query after signature verification.
                        $query = $gateway->query_status($provider_ref !== '' ? $provider_ref : $order_number);
                        if (!empty($query['success']) && ($query['status'] ?? '') === 'paid') {
                            if (empty($query['order_number'])) {
                                $query['order_number'] = $order_number;
                            }
                            if ($this->complete_order($gateway_id, $query)) {
                                $status = 'success';
                            }
                        }
                    }
                }
            } elseif ($gateway_id === 'paypal' && method_exists($gateway, 'capture_order')) {
                // PayPal v2：用户批准后在 return 时捕获（token = PayPal 订单号）
                $paypal_order_id = sanitize_text_field((string) ($request->get_param('token') ?: ''));
                if ($paypal_order_id !== '') {
                    $cap = $gateway->capture_order($paypal_order_id);
                    if (!empty($cap['success']) && ($cap['status'] ?? '') === 'paid') {
                        $captured_ref = sanitize_text_field((string) ($cap['order_number'] ?? ''));
                        $captured_order = $this->local_order_number($captured_ref);
                        if ($captured_order === ''
                            || ($order_number !== '' && !hash_equals($order_number, $captured_order))) {
                            $this->redirect_to_orders($order_number, 'pending');
                            return null;
                        }
                        $order_number = $captured_order;
                        if ($this->complete_order($gateway_id, $cap)) {
                            $status = 'success';
                        }
                    }
                }
            } elseif ($order_number !== '') {
                // 其余网关：用返回时的 provider ref 查询该次尝试；local number 仅用于跳转。
                $q = $gateway->query_status($provider_ref !== '' ? $provider_ref : $order_number);
                if (!empty($q['success']) && ($q['status'] ?? '') === 'paid') {
                    if (empty($q['order_number'])) {
                        $q['order_number'] = $order_number;
                    }
                    if ($this->complete_order($gateway_id, $q)) {
                        $status = 'success';
                    }
                }
            }
        }

        $this->redirect_to_orders($order_number, $status);
        return null;
    }

    /**
     * 用户取消支付，跳回订单中心。
     */
    public function handle_cancel(\WP_REST_Request $request) {
        $provider_ref = sanitize_text_field((string) ($request->get_param('order')
            ?: $request->get_param('out_trade_no')
            ?: ''));
        $this->redirect_to_orders($this->local_order_number($provider_ref), 'cancelled');
        return null;
    }

    /**
     * Map a provider out_trade_no back to the local order number (identity when unknown).
     */
    private function local_order_number(string $provider_ref): string {
        if ($provider_ref === '' || !class_exists('AKSRT\\Payment\\OrderRepository')) {
            return $provider_ref;
        }
        $order = OrderRepository::get_instance()->resolve_by_out_trade_no($provider_ref);
        if (!$order) {
            return $provider_ref;
        }
        return sanitize_text_field((string) ($order['order_number'] ?? $provider_ref));
    }

    /**
     * Whether a pending order can be reconciled against an external provider.
     *
     * This is the single gate used by the order view and the actual reconcile
     * operation, so ordinary detail reads never trigger provider I/O.
     *
     * @param array<string,mixed>|null $order
     */
    public function needs_reconciliation(?array $order): bool {
        return null !== $this->reconciliation_gateway($order);
    }

    /**
     * Reconcile a pending external order against the configured provider.
     *
     * @param array<string,mixed>|null $order
     */
    public function reconcile_order(string $order_number, ?array $order = null): ?array {
        if ($order_number === '' || !class_exists('AKSRT\\Payment\\OrderRepository')) {
            return $order;
        }
        $repo  = OrderRepository::get_instance();
        $order = is_array($order) ? $order : $repo->get($order_number);
        $gateway = $this->reconciliation_gateway($order);
        if (!$gateway) {
            return $order;
        }
        $gateway_id = sanitize_key((string) ($order['payment_method'] ?? ''));

        $throttle_key = 'aksrt_reconcile_' . hash('sha256', $order_number);
        if (get_transient($throttle_key)) {
            return $order;
        }
        set_transient($throttle_key, 1, 5);

        $lock = PaymentAttemptLock::acquire('reconcile_' . $order_number);
        if ($lock === false) {
            return $repo->get($order_number) ?: $order;
        }
        try {
            $provider_ref = OrderRepository::provider_out_trade_no($order);
            $query = $gateway->query_status($provider_ref);
            if (!empty($query['success']) && ($query['status'] ?? '') === 'paid') {
                if (empty($query['order_number'])) {
                    $query['order_number'] = $provider_ref;
                }
                $this->complete_order($gateway_id, $query);
            }
        } catch (\Throwable $e) {
            if (defined('WP_DEBUG') && WP_DEBUG) {
                error_log(sprintf('[AKSRT Payment] reconcile failed order=%s gateway=%s: %s', $order_number, $gateway_id, $e->getMessage()));
            }
        } finally {
            PaymentAttemptLock::release('reconcile_' . $order_number, $lock);
        }

        return $repo->get($order_number) ?: $order;
    }

    /**
     * @param array<string,mixed>|null $order
     */
    private function reconciliation_gateway(?array $order): ?GatewayInterface {
        if (!is_array($order) || !in_array((string) ($order['status'] ?? ''), [Order::STATUS_CREATED, Order::STATUS_PENDING], true)) {
            return null;
        }

        $gateway_id = sanitize_key((string) ($order['payment_method'] ?? ''));
        if ($gateway_id === '' || in_array($gateway_id, ['balance', 'points', 'manual_review'], true)) {
            return null;
        }
        $gateway = $this->get_gateway($gateway_id);
        return $gateway && $gateway->is_configured() ? $gateway : null;
    }

    /**
     * 幂等、带金额校验的订单完成。仅由验签通过的回调调用。
     *
     * @param string $gateway_id 网关 ID
     * @param array  $verify     网关 verify_callback / query 结果
     * @return bool
     */
    public function complete_order(string $gateway_id, array $verify): bool {
        $provider_out_trade_no = sanitize_text_field((string) ($verify['order_number'] ?? ''));
        if ($provider_out_trade_no === '' || !class_exists('AKSRT\\Payment\\OrderRepository')) {
            return false;
        }

        $repo  = OrderRepository::get_instance();
        // Callbacks may carry attempt-suffixed out_trade_no (…P2); map back to local order.
        $order = $repo->resolve_by_out_trade_no($provider_out_trade_no);
        if (!$order) {
            return false;
        }
        $order_number = sanitize_text_field((string) ($order['order_number'] ?? ''));
        if ($order_number === '') {
            return false;
        }

        $stored_gateway = sanitize_key((string) ($order['payment_method'] ?? ''));
        if ($stored_gateway === '' || !hash_equals($stored_gateway, sanitize_key($gateway_id))) {
            return false;
        }

        // Provider-confirmed external payments must include an exact amount and transaction ID.
        $expected_currency = strtoupper((string) ($order['currency'] ?? ''));
        $paid_currency = strtoupper(sanitize_key((string) ($verify['currency'] ?? '')));
        $expected       = (float) ($order['amount'] ?? 0);
        $paid_amount    = (float) ($verify['amount'] ?? 0);
        $transaction_id = sanitize_text_field((string) ($verify['transaction_id'] ?? ''));
        if ($expected <= 0
            || $paid_amount <= 0
            || $transaction_id === ''
            || $expected_currency === ''
            || $paid_currency === ''
            || !hash_equals($expected_currency, $paid_currency)
            || abs($expected - $paid_amount) > 0.01) {
            if (defined('WP_DEBUG') && WP_DEBUG) {
                error_log(sprintf(
                    '[AKSRT Payment] invalid completion order=%s out_trade_no=%s expected=%.2f %s paid=%.2f %s transaction=%s gateway=%s',
                    $order_number,
                    $provider_out_trade_no,
                    $expected,
                    $expected_currency,
                    $paid_amount,
                    $paid_currency,
                    $transaction_id !== '' ? 'present' : 'missing',
                    $gateway_id
                ));
            }
            return false;
        }

        $current = (string) ($order['status'] ?? '');

        // 幂等：仅同一交易号的重复回调可视为成功。不同交易号意味着
        // 用户可能重复付款，不能静默 ACK 为已正确同步。
        if (in_array($current, ['paid', 'delivered', 'completed'], true)) {
            $stored_transaction = sanitize_text_field((string) ($order['payment_transaction_id'] ?? ''));
            return $stored_transaction !== '' && hash_equals($stored_transaction, $transaction_id);
        }
        // 只允许从未支付态完成
        if (!in_array($current, ['created', 'pending'], true)) {
            return false;
        }

        return $repo->update_status($order_number, Order::STATUS_PAID, [
            'payment_method'         => $gateway_id,
            'payment_transaction_id' => $transaction_id,
            'note'                   => __('支付网关回调确认到账。', 'aksrt'),
        ]);
    }

    private function redirect_to_orders(string $order_number, string $status): void {
        $url = add_query_arg(array_filter([
            'payment' => sanitize_key($status),
            'order'   => $order_number,
        ]), $this->orders_page_url());

        nocache_headers();
        wp_safe_redirect($url);
        exit;
    }

    private function orders_page_url(): string {
        $pages = get_posts([
            'post_type'      => 'page',
            'post_status'    => 'publish',
            'posts_per_page' => 1,
            'meta_key'       => '_wp_page_template',
            'meta_value'     => 'templates/pages/page-orders.php',
            'fields'         => 'ids',
            'no_found_rows'  => true,
        ]);

        if (!empty($pages)) {
            return (string) get_permalink((int) $pages[0]);
        }

        return home_url('/orders/');
    }
}