<?php
/**
 * AKSRT PayPal Gateway — PayPal 支付网关
 *
 * 使用 WordPress HTTP API 直接调用 PayPal REST API，无需第三方 SDK。
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_PayPal_Gateway implements AKSRT_Payment_Gateway_Interface {

    public function get_id(): string {
        return 'paypal';
    }

    public function get_name(): string {
        return __('PayPal', 'aksrt');
    }

    public function is_configured(): bool {
        $config = $this->get_config();
        return !empty($config['client_id']) && !empty($config['client_secret']);
    }

    public function create_payment(array $order): array {
        if (!$this->is_configured()) {
            return ['success' => false, 'message' => __('PayPal 未配置', 'aksrt')];
        }

        $config = $this->get_config();
        $order_number = $order['order_number'] ?? '';
        $amount = (float) ($order['amount'] ?? 0);
        $subject = $order['subject'] ?? __('订单支付', 'aksrt');
        $currency = $config['currency'] ?? 'USD';

        try {
            $response = $this->api_request('POST', '/v2/checkout/orders', [
                'intent' => 'CAPTURE',
                'purchase_units' => [[
                    'reference_id' => $order_number,
                    'description'  => $subject,
                    'amount'       => [
                        'currency_code' => $currency,
                        'value'         => number_format($amount, 2, '.', ''),
                    ],
                ]],
                'application_context' => [
                    'return_url'  => home_url('/wp-json/aksrt/v1/payment/paypal/return?order=' . $order_number),
                    'cancel_url'  => home_url('/wp-json/aksrt/v1/payment/paypal/cancel?order=' . $order_number),
                    'brand_name'  => get_bloginfo('name'),
                    'user_action' => 'PAY_NOW',
                ],
            ]);

            if ($response['status'] === 201) {
                $data = $response['body'];
                $approveUrl = '';
                foreach ($data['links'] ?? [] as $link) {
                    if ($link['rel'] === 'approve') {
                        $approveUrl = $link['href'];
                        break;
                    }
                }

                return [
                    'success'      => true,
                    'payment_url'  => $approveUrl,
                    'payment_data' => [
                        'order_number' => $order_number,
                        'paypal_id'    => $data['id'] ?? '',
                    ],
                    'message'      => __('PayPal 订单已创建', 'aksrt'),
                ];
            }

            return ['success' => false, 'message' => $response['body']['message'] ?? __('PayPal 创建失败', 'aksrt')];
        } catch (\Exception $e) {
            return ['success' => false, 'message' => $e->getMessage()];
        }
    }

    public function verify_callback(WP_REST_Request $request): array {
        try {
            $body = json_decode($request->get_body(), true);
            $eventType = $body['event_type'] ?? '';

            if ($eventType !== 'CHECKOUT.ORDER.APPROVED') {
                return ['success' => false, 'message' => __('非支付完成事件', 'aksrt')];
            }

            $resource = $body['resource'] ?? [];
            $orderNumber = '';
            $amount = 0;

            foreach ($resource['purchase_units'] ?? [] as $unit) {
                $orderNumber = $unit['reference_id'] ?? '';
                $amount = (float) ($unit['amount']['value'] ?? 0);
                break;
            }

            return [
                'success'        => true,
                'order_number'   => $orderNumber,
                'amount'         => $amount,
                'transaction_id' => $resource['id'] ?? '',
                'status'         => 'paid',
            ];
        } catch (\Exception $e) {
            return ['success' => false, 'message' => $e->getMessage()];
        }
    }

    public function query_status(string $order_number): array {
        return [
            'success' => true,
            'status'  => 'pending',
            'message' => __('PayPal 状态通过 Webhook 更新', 'aksrt'),
        ];
    }

    public function refund(string $order_number, float $amount): array {
        return [
            'success' => false,
            'message' => __('PayPal 退款需要通过后台手动处理', 'aksrt'),
        ];
    }

    private function get_config(): array {
        // 优先从统一设置读取（schema 保存的 key）
        if (class_exists('AKSRT_Settings')) {
            $all = AKSRT_Settings::get_all();
            if (!empty($all['paypal_client_id'])) {
                return [
                    'client_id'     => $all['paypal_client_id'] ?? '',
                    'client_secret' => $all['paypal_client_secret'] ?? '',
                    'currency'      => $all['paypal_currency'] ?? 'USD',
                    'mode'          => !empty($all['paypal_sandbox']) ? 'sandbox' : 'live',
                ];
            }
        }
        // 回退到独立 option
        $settings = get_option('aksrt_payment_paypal', []);
        return is_array($settings) ? $settings : [];
    }

    /**
     * 捕获已批准的 PayPal 订单（v2 CAPTURE 必需步骤）。
     * 用户在 return_url 返回后调用，确认真正扣款。
     *
     * @param string $paypal_order_id PayPal 订单 ID（create 时返回的 id）
     * @return array{success:bool, order_number?:string, amount?:float, transaction_id?:string, status?:string, message?:string}
     */
    public function capture_order(string $paypal_order_id): array {
        if ($paypal_order_id === '') {
            return ['success' => false, 'message' => __('缺少 PayPal 订单号', 'aksrt')];
        }

        try {
            $response = $this->api_request('POST', '/v2/checkout/orders/' . rawurlencode($paypal_order_id) . '/capture');
            $body = $response['body'];

            if (in_array($response['status'], [200, 201], true) && ($body['status'] ?? '') === 'COMPLETED') {
                $unit = $body['purchase_units'][0] ?? [];
                $capture = $unit['payments']['captures'][0] ?? [];
                return [
                    'success'        => true,
                    'order_number'   => $unit['reference_id'] ?? '',
                    'amount'         => (float) ($capture['amount']['value'] ?? 0),
                    'transaction_id' => $capture['id'] ?? ($body['id'] ?? ''),
                    'status'         => 'paid',
                ];
            }

            return ['success' => false, 'message' => $body['message'] ?? __('PayPal 捕获失败', 'aksrt')];
        } catch (\Exception $e) {
            return ['success' => false, 'message' => $e->getMessage()];
        }
    }

    /**
     * 获取 OAuth2 access token（v2 REST 必需）。
     */
    private function get_access_token(): string {
        $config = $this->get_config();
        $isSandbox = ($config['mode'] ?? 'live') === 'sandbox';
        $baseUrl = $isSandbox ? 'https://api-m.sandbox.paypal.com' : 'https://api-m.paypal.com';

        $response = wp_remote_post($baseUrl . '/v1/oauth2/token', [
            'headers' => [
                'Authorization' => 'Basic ' . base64_encode(($config['client_id'] ?? '') . ':' . ($config['client_secret'] ?? '')),
                'Content-Type'  => 'application/x-www-form-urlencoded',
            ],
            'body'    => 'grant_type=client_credentials',
            'timeout' => 30,
        ]);

        if (is_wp_error($response)) {
            throw new \Exception($response->get_error_message());
        }

        $body = json_decode(wp_remote_retrieve_body($response), true);
        $token = $body['access_token'] ?? '';
        if ($token === '') {
            throw new \Exception($body['error_description'] ?? __('PayPal 鉴权失败', 'aksrt'));
        }

        return (string) $token;
    }

    /**
     * 调用 PayPal REST API（带 OAuth2 Bearer token）
     */
    private function api_request(string $method, string $endpoint, array $data = []): array {
        $config = $this->get_config();
        $isSandbox = ($config['mode'] ?? 'live') === 'sandbox';
        $baseUrl = $isSandbox
            ? 'https://api-m.sandbox.paypal.com'
            : 'https://api-m.paypal.com';

        $url = $baseUrl . $endpoint;

        $headers = [
            'Content-Type'  => 'application/json',
            'Authorization' => 'Bearer ' . $this->get_access_token(),
        ];

        $args = [
            'method'  => $method,
            'headers' => $headers,
            'timeout' => 30,
        ];
        if (!empty($data)) {
            $args['body'] = wp_json_encode($data);
        }

        $response = wp_remote_request($url, $args);

        if (is_wp_error($response)) {
            throw new \Exception($response->get_error_message());
        }

        $status = wp_remote_retrieve_response_code($response);
        $body = json_decode(wp_remote_retrieve_body($response), true);

        return [
            'status' => $status,
            'body'   => $body ?: [],
        ];
    }
}