<?php

/**
 * Custom Paypal gateway for Acadlix.
 *
 * IMPORTANT:
 * This is NOT the PayPal PHP SDK.
 * No third-party PayPal library is bundled or loaded.
 *
 * @package Acadlix
 */

namespace Yuvayana\Acadlix\Common\Payments\Gateways;

use Yuvayana\Acadlix\Common\Models\Order;

defined('ABSPATH') || exit();

use Yuvayana\Acadlix\Common\Payments\PaymentGatewayInterface;
use Exception;
use WP_Error;
use WP_REST_Response;

// Prevent class re-declaration when another plugin loads a class with the same FQCN.
if (!class_exists(__NAMESPACE__ . '\\Paypal')) {
  class Paypal implements PaymentGatewayInterface
  {
    const API_URL_TEST = 'https://api-m.sandbox.paypal.com';
    const API_URL_LIVE = 'https://api-m.paypal.com';
    const CONNECTION_TIMEOUT = 30;

    protected bool $is_paypal_active;
    protected string $paypal_url;
    protected bool $sandbox;
    protected string $client_id;
    protected string $secret_key;
    protected string $webhook_id;
    protected float $amount;
    protected string $currency;
    protected array $billing_info;
    protected array $order_items;

    public function __construct()
    {
      $this->sandbox = acadlix()->helper()->acadlix_get_option('acadlix_paypal_sandbox') === 'yes';
      $this->paypal_url = $this->sandbox ? self::API_URL_TEST : self::API_URL_LIVE;
      $this->client_id = acadlix()->helper()->acadlix_get_option('acadlix_paypal_client_id');
      $this->secret_key = acadlix()->helper()->acadlix_get_option('acadlix_paypal_secret_key');
      $this->webhook_id = acadlix()->helper()->acadlix_get_option('acadlix_paypal_webhook_id');
      $this->is_paypal_active = acadlix()->helper()->acadlix_get_option('acadlix_paypal_active') === 'yes';
    }

    public function is_paypal_active()
    {
      if ($this->is_paypal_active && $this->client_id && $this->secret_key && $this->webhook_id) {
        return true;
      }
      return false;
    }

    public function setAmount(float $amount): self
    {
      $this->amount = $amount;
      return $this;
    }

    public function setCurrency(string $currency): self
    {
      $this->currency = $currency;
      return $this;
    }

    public function setBillingInfo(array $billing_info): self
    {
      $this->billing_info = $billing_info;
      return $this;
    }

    public function setOrderItems(array $order_items): self
    {
      $this->order_items = $order_items;
      return $this;
    }

    protected function formatPayPalAmount($amount)
    {
      // Round safely to 2 decimal places
      $rounded = round((float) $amount, 2);

      // Format with 2 decimals as string
      return number_format($rounded, 2, '.', '');
    }

    protected function getPayPalAccessToken(): ?string
    {
      $header = [
        'Authorization' => 'Basic ' . base64_encode($this->client_id . ':' . $this->secret_key),
        'Content-Type' => 'application/x-www-form-urlencoded',
      ];
      $body = [
        'grant_type' => 'client_credentials'
      ];
      $response = wp_remote_post($this->paypal_url . '/v1/oauth2/token', [
        'headers' => $header,
        'body' => $body,
      ]);

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

      $result = wp_remote_retrieve_body($response);
      $result = json_decode($result);

      $status_code = wp_remote_retrieve_response_code($response);

      if ($status_code < 200 || $status_code > 299) {
        throw new Exception(esc_html($result->error_description));
      }

      return $result->access_token ?? null;
    }

    protected function get_request_headers(): array
    {
      if (!$this->getPayPalAccessToken()) {
        throw new Exception('PayPal access token failed');
      }
      return [
        'Authorization' => 'Bearer ' . $this->getPayPalAccessToken(),
        'Content-Type' => 'application/json',
      ];
    }

    protected function createConnection($url, $method, $data = [], $retry = 1)
    {
      $args = [
        'method' => $method,
        'headers' => $this->get_request_headers(),
        'timeout' => self::CONNECTION_TIMEOUT,
      ];

      if ($method !== 'GET' && !empty($data)) {
        $args['body'] = wp_json_encode($data);
      }

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

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

      $result = wp_remote_retrieve_body($response);
      $result = json_decode($result);

      $status_code = wp_remote_retrieve_response_code($response);

      if ($status_code === 401) {
        throw new Exception(esc_html($result->error_description));
      }

      return $result;
    }

    protected function returnUrl()
    {
      $thankyou_page_id = acadlix()->helper()->acadlix_get_option('acadlix_thankyou_page_id');
      $nonce = wp_create_nonce('acadlix_payment_nonce');
      $url = add_query_arg("nonce", $nonce, get_permalink($thankyou_page_id));
      return esc_url($url);
    }

    protected function cancelUrl()
    {
      return add_query_arg('cancelled', true, $this->returnUrl());
    }

    protected function getOrderBody(): array
    {
      $billing_info = $this->billing_info;
      $body = [
        'intent' => 'CAPTURE',
        'purchase_units' => [
          [
            'amount' => [
              'currency_code' => $this->currency,
              'value' => $this->formatPayPalAmount($this->amount),
            ],
          ]
        ],
        'payment_source' => [
          'paypal' => [
            'experience_context' => [
              'shipping_preference' => 'NO_SHIPPING',
              'user_action' => 'PAY_NOW',
              'locale' => str_replace('_', '-', get_locale()),
              'return_url' => $this->returnUrl(),
              'cancel_url' => $this->cancelUrl(),
              'payment_method_preference' => 'IMMEDIATE_PAYMENT_REQUIRED',
            ],
          ],
        ],
      ];
      if (isset($billing_info) && null !== $billing_info['country_code']) {
        $body['purchase_units'][0]['shipping'] = [
          'name' => [
            'full_name' => $billing_info['first_name'] . ' ' . $billing_info['last_name'],
          ],
          'email_address' => $billing_info['email'] ?? '',
          'address' => [
            'address_line_1' => $billing_info['address'] ?? '',
            'admin_area_2' => $billing_info['city'] ?? '',
            'admin_area_1' => $billing_info['city'] ?? '',
            'postal_code' => $billing_info['zip_code'] ?? '',
            'country_code' => $billing_info['country_code'] ?? '',
          ],
        ];

        $body['payment_source']['paypal']['experience_context']['shipping_preference'] = 'SET_PROVIDED_ADDRESS';
      } else {
        $body['payment_source']['paypal']['experience_context']['shipping_preference'] = 'NO_SHIPPING';
      }
      return $body;
    }

    protected function createPaypalOrder()
    {
      $body = $this->getOrderBody();

      $result = $this->createConnection(
        $this->paypal_url . '/v2/checkout/orders',
        'POST',
        $body
      );

      if (isset($result->details)) {
        throw new Exception(esc_html(trim($result->details[0]->description)));
      } elseif (isset($result->message)) {
        throw new Exception(esc_html(trim($result->message)));
      }

      if (isset($result->id)) {
        return $result;
      }
      throw new Exception('Something went wrong. Please try again later.');
    }

    protected function getPaypalOrderDetail($paypal_order_id)
    {
      $result = $this->createConnection(
        $this->paypal_url . '/v2/checkout/orders/' . $paypal_order_id,
        'GET'
      );

      if (!isset($result->status) || $paypal_order_id !== $result->id) {
        throw new Exception('Something went wrong. Please try again later.');
      }

      return $result;
    }

    protected function capturePayment($paypal_order_id)
    {
      $result = $this->createConnection(
        $this->paypal_url . '/v2/checkout/orders/' . $paypal_order_id . '/capture',
        'POST'
      );

      if (isset($result->message) || $paypal_order_id === $result->id) {
        return $result;
      }

      throw new Exception('Something went wrong. Please try again later.');
    }

    protected function get_action_link($payment_order, $action)
    {
      foreach ($payment_order->links as $link) {
        if ($action === $link->rel) {
          return $link->href;
        }
      }
      return null;
    }

    public function getOrder($paypal_order_id)
    {
      $order_meta = acadlix()
        ->model()
        ->orderMeta()
        ->where('meta_key', 'paypal_order_id')
        ->where('meta_value', $paypal_order_id)
        ->first();
      return $order_meta
        ? acadlix()->model()->order()->find($order_meta->order_id)
        : null;
    }

    protected function successOrder($order)
    {
      if (!$order) {
        throw new Exception('Order not found');
      }

      $order->success_order();
      $message = 'Order status updated to success';
      $order->createActivityLog($message);
      
      if ($order->order_items()->count() > 0) {
        foreach ($order->order_items as $item) {
          $cart = acadlix()
            ->model()
            ->courseCart()
            ->where('user_id', $order->user_id)
            ->where('item_id', $item->item_id)
            ->where('type', $item->type)
            ->first();
          if ($cart) {
            $cart->delete();
          }
        }
      }
      return ['success' => true, 'message' => 'Order captured successfully'];
    }

    public function failedOrder($order, $message = '')
    {
      if (!$order) {
        throw new Exception('Order not found');
      }
      $order->failed_order();
      $msg = 'Order status updated to failed';
      $order->createActivityLog($msg);
      $order->updateOrCreateMeta('failure_reason', $message);
      return ['success' => true, 'message' => $message];
    }

    public function processOrder(): array|object|null
    {
      if (!$this->is_paypal_active()) {
        throw new Exception('PayPal not active');
      }
      $result = $this->createPaypalOrder();
      $result->redirect_url = $this->get_action_link($result, 'payer-action');
      return $result;
    }

    public function verifyWebhook(array $data): WP_REST_Response|WP_Error
    {
      try {
        if (!$this->is_paypal_active()) {
          throw new Exception('PayPal not active');
        }

        $headers = $data['headers'] ?? [];
        $body = $data['stream'] ?? '';
        $verify_payload = [
          'auth_algo' => $headers['paypal_auth_algo'],
          'cert_url' => $headers['paypal_cert_url'],
          'transmission_id' => $headers['paypal_transmission_id'],
          'transmission_sig' => $headers['paypal_transmission_sig'],
          'transmission_time' => $headers['paypal_transmission_time'],
          'webhook_id' => $this->webhook_id,
          'webhook_event' => json_decode($body),
        ];

        $url = $this->paypal_url . '/v1/notifications/verify-webhook-signature';
        $result = $this->createConnection($url, 'POST', $verify_payload);

        if (!isset($result->verification_status) || $result->verification_status !== 'SUCCESS') {
          throw new Exception('PayPal webhook verification failed: ' . $result->verification_status);
        }
        $event = json_decode($body);
        switch ($event->event_type) {
          case 'CHECKOUT.ORDER.APPROVED':
            $paypal_order_id = $event->resource->id ?? '';
            $response = $this->orderCapture($paypal_order_id);
            $response = new WP_REST_Response($response, 200);
            break;
          default:
            $response = new WP_REST_Response(['message' => 'Event ignored'], 200);
            break;
        }
        return $response;
      } catch (Exception $e) {
        return new WP_Error(
          'webhook_error',
          __('PayPal webhook error: ', 'acadlix') . esc_html($e->getMessage()),
          ['status' => 500]
        );
      }
    }

    protected function orderCapture($paypal_order_id)
    {
      try {
        if (empty($paypal_order_id)) {
          throw new Exception('PayPal order id not found');
        }
        $order = $this->getOrder($paypal_order_id);
        if (!$order) {
          throw new Exception('Order not found');
        }

        if ($order->status == Order::STATUS_SUCCESS) {
          return ['success' => true, 'message' => 'Order already processed'];
        }

        $order_details = $this->getPaypalOrderDetail($paypal_order_id);

        if ($order_details->status !== 'APPROVED') {
          return $this->failedOrder($order, 'Order not approved');
        }

        // capture order if order status is approved.
        $capture = $this->capturePayment($paypal_order_id);

        if (isset($capture->details)) {
          $this->failedOrder($order, $capture->details[0]->description);
        } elseif (isset($capture->message)) {
          return $this->failedOrder($paypal_order_id, $capture->message);
        }

        if ($capture->status !== 'COMPLETED') {
          return $this->failedOrder($order, $capture->message);
        }

        return $this->successOrder($order);
      } catch (Exception $e) {
        throw new Exception(esc_html($e->getMessage()));
      }
    }

    public function verifyOrder($paypal_order_id): void
    {
      try {
        if (!$this->is_paypal_active()) {
          throw new Exception('PayPal not active');
        }
        if (!$paypal_order_id) {
          throw new Exception('PayPal order id not found');
        }
        $this->orderCapture($paypal_order_id);
      } catch (Exception $e) {
        return;
      }
    }
  }
}