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

namespace AKSRT\Payment\Gateways;

defined('ABSPATH') || exit;

class PayPalGateway implements \AKSRT\Payment\GatewayInterface {

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

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

    public function is_configured(): bool {
        if (class_exists('\AKSRT\Settings\PaymentRuntime')
            && !\AKSRT\Settings\PaymentRuntime::is_gateway_enabled('paypal')) {
            return false;
        }
        $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();
        $order_number = (string) ($order['order_number'] ?? '');
        // Re-pay attempts carry a fresh provider number; the callback resolves it back.
        $out_trade_no = (string) ($order['out_trade_no'] ?? '');
        if ($out_trade_no === '') {
            $out_trade_no = class_exists('\AKSRT\Payment\OrderRepository')
                ? \AKSRT\Payment\OrderRepository::provider_out_trade_no($order)
                : $order_number;
        }
        $amount = $this->amount_string($order['amount'] ?? null);
        $subject = $order['subject'] ?? __('订单支付', 'aksrt');
        $order_currency = strtoupper((string) ($order['currency'] ?? ''));
        $currency = strtoupper((string) ($config['currency'] ?? 'USD'));
        if ($order_currency === '' || !hash_equals($order_currency, $currency)) {
            return ['success' => false, 'message' => __('PayPal 币种与订单币种不一致', 'aksrt')];
        }
		if ($order_number === '' || $out_trade_no === '' || $amount === null) {
			return ['success' => false, 'message' => __('订单金额无效', 'aksrt')];
		}

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

                if ($order_number !== '' && class_exists('\AKSRT\Payment\OrderRepository')) {
                    $persisted = \AKSRT\Payment\OrderRepository::get_instance()->merge_meta($order_number, [
                        'paypal_order_id' => (string) ($data['id'] ?? ''),
                    ]);
                    if (!$persisted) {
                        return ['success' => false, 'message' => __('PayPal 支付单保存失败，请重试', 'aksrt')];
                    }
                }

                return [
                    'success'      => true,
                    'payment_url'  => $approveUrl,
                    'payment_data' => [
                        'order_number' => $order_number,
                        'out_trade_no' => $out_trade_no,
                        '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 {
        // PayPal orders are finalized only by the authenticated capture call in handle_return().
        // Never treat an unsigned CHECKOUT.ORDER.APPROVED webhook as payment completion.
        return [
            'success' => false,
            'status'  => 'pending',
            'message' => __('PayPal 支付需在返回流程中完成捕获确认', 'aksrt'),
        ];
    }

    public function query_status(string $order_number): array {
        if (!$this->is_configured() || !class_exists('\AKSRT\Payment\OrderRepository')) {
            return ['success' => false, 'status' => 'pending', 'message' => __('PayPal 未配置', 'aksrt')];
        }
        $order = \AKSRT\Payment\OrderRepository::get_instance()->resolve_by_out_trade_no($order_number);
        $meta = is_array($order['meta_payload'] ?? null) ? $order['meta_payload'] : [];
        $paypal_order_id = sanitize_text_field((string) ($meta['paypal_order_id'] ?? ''));
        if ($paypal_order_id === '') {
            return ['success' => true, 'status' => 'pending', 'message' => __('PayPal 支付尚未建立', 'aksrt')];
        }
        try {
            $response = $this->api_request('GET', '/v2/checkout/orders/' . rawurlencode($paypal_order_id));
            $body = $response['body'];
            if ($response['status'] !== 200 || !is_array($body)) {
                return ['success' => false, 'status' => 'pending', 'message' => __('PayPal 状态查询失败', 'aksrt')];
            }
            if (($body['status'] ?? '') === 'APPROVED') {
                return $this->capture_order($paypal_order_id);
            }
            if (($body['status'] ?? '') === 'COMPLETED') {
                return $this->completed_order_evidence($body);
            }
            return ['success' => true, 'status' => 'pending', 'message' => __('PayPal 支付处理中', 'aksrt')];
        } catch (\Throwable $e) {
            return ['success' => false, 'status' => 'pending', 'message' => $e->getMessage()];
        }
    }

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

    private function get_config(): array {
        if (!class_exists('\AKSRT\Settings\Settings')) {
            return [];
        }
        $all = \AKSRT\Settings\Settings::get_all();
        return [
            'client_id'     => (string) ($all['paypal_client_id'] ?? ''),
            'client_secret' => (string) ($all['paypal_client_secret'] ?? ''),
            'currency'      => (string) ($all['paypal_currency'] ?? 'USD'),
            'mode'          => !empty($all['paypal_sandbox']) ? 'sandbox' : 'live',
        ];
    }

    /**
     * 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?:string, 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') {
                return $this->completed_order_evidence($body);
            }

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

    /** @param array<string,mixed> $body */
    private function completed_order_evidence(array $body): array {
        $unit = $body['purchase_units'][0] ?? [];
        $capture = $unit['payments']['captures'][0] ?? [];
		$amount = $this->amount_string($capture['amount']['value'] ?? null);
		if ($amount === null) {
			return ['success' => false, 'message' => __('PayPal 返回金额无效', 'aksrt')];
		}
        return [
            'success'        => true,
            'order_number'   => (string) ($unit['reference_id'] ?? ''),
            'amount'         => $amount,
            'currency'       => strtoupper((string) ($capture['amount']['currency_code'] ?? '')),
            'transaction_id' => (string) ($capture['id'] ?? ($body['id'] ?? '')),
            'status'         => 'paid',
        ];
    }

	private function amount_string(mixed $value): ?string {
		if (!is_string($value)) {
			return null;
		}
		try {
			$amount = \AKSRT\Ledger\AssetAmount::balance(trim($value));
			return $amount->minor() > 0 ? $amount->decimal() : null;
		} catch (\InvalidArgumentException $e) {
			return null;
		}
	}

    /**
     * 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 ?: [],
        ];
    }
}