Adding a NowPayments plugin (troubleshooting)

So I am trying to make a plugin that adds another gateway for NowPayments payment with xmr (monero) cryptocurrency.

https://imgur.com/a/yttNviK some screens from the menus for the plugin. The problem is when I am trying to checkout I get no redirection to the nowpayments site and I get to the confirmation page saying I paid with 0 dollars and the payment method is blank. I get no specific errors either so I definitely need help to get this plugin working. Maybe you can help me?

Here is my code for the ipn handler and I know this works cause I have tested it with postman app and with a curl command.

<?php
// Enable error reporting for debugging
error_reporting(E_ALL);
ini_set('display_errors', 1);
ini_set('log_errors', 1);
ini_set('error_log', '/path/to/php-error.log'); // Update this path

error_log('IPN Handler Started');

// Retrieve the secret key
$secret = 'your-secret-key'; // Ensure this is correct

// Get the raw POST data
$payload = file_get_contents('php://input');
error_log('Received Payload: ' . $payload);

// Get the signature from the headers
$signature = isset($_SERVER['HTTP_X_NOWPAYMENTS_SIG']) ? $_SERVER['HTTP_X_NOWPAYMENTS_SIG'] : '';
error_log('Received Signature: ' . $signature);

// Calculate the expected signature
$calculated_signature = hash_hmac('sha512', $payload, $secret);
error_log('Calculated Signature: ' . $calculated_signature);

// Verify the signature
if ($calculated_signature === $signature) {
    error_log('Signature verified successfully.');

    // Decode the payload
    $data = json_decode($payload, true);
    if ($data === null) {
        error_log('JSON Decode Error: ' . json_last_error_msg());
    } else {
        error_log('Decoded Data: ' . print_r($data, true));

        // Process the payment status
        if (isset($data['status']) && $data['status'] === 'paid') {
            error_log('Payment confirmed for order: ' . $data['order_id']);
            // Handle the payment logic here
        } else {
            error_log('Invalid status: ' . $data['status']);
        }
    }
} else {
    error_log('Signature verification failed');
    error_log('Received Signature: ' . $signature);
    error_log('Calculated Signature: ' . $calculated_signature);
}

// Send response
http_response_code(200);
exit();
?>

and here is the main plugin code that probably needs some revising:

<?php
/*
Plugin Name: Paid Memberships Pro - Add NowPayments
Plugin URI: https://example.com
Description: Add NowPayments as a Payment Option for Monero and other cryptocurrencies.
Version: 0.2
Author: Your Name
Author URI: https://example.com
Text Domain: pmpro-add-nowpayments
Domain Path: /languages
*/

// Load plugin text domain
function pmpro_add_nowpayments_i18n() {
    load_plugin_textdomain('pmpro-add-nowpayments', false, basename(dirname(__FILE__)) . '/languages'); 
}
add_action('plugins_loaded', 'pmpro_add_nowpayments_i18n', 10);

// Register plugin styles
function pmpro_add_nowpayments_register_styles() {
    wp_register_style('pmpro-add-nowpayments-styles', plugins_url('css/pmpro-add-nowpayments.css', __FILE__));
    wp_enqueue_style('pmpro-add-nowpayments-styles');
}
add_action('wp_enqueue_scripts', 'pmpro_add_nowpayments_register_styles');

// Add NowPayments to gateways
function pmproaddnowpayments_pmpro_gateways($gateways) {
    $gateways['nowpayments'] = __('NowPayments (Cryptocurrency)', 'pmpro-add-nowpayments');
    return $gateways;
}


add_filter('pmpro_gateways', 'pmproaddnowpayments_pmpro_gateways');

add_action('pmpro_checkout_before_payment_information_fields', function() {
    global $pmpro_requirebilling;
});


// Log the current billing requirement at checkout
function log_billing_requirement_in_checkout() {
    global $pmpro_requirebilling;
    error_log('Billing requirement during checkout (before filter): ' . (isset($pmpro_requirebilling) ? $pmpro_requirebilling : 'Not set'));
}
add_action('pmpro_checkout_boxes', 'log_billing_requirement_in_checkout');

// Log billing requirement after filter is applied
function log_billing_requirement($require_billing) {
    return $require_billing;
}
add_filter('pmpro_require_billing', 'log_billing_requirement', 15);

function pmproaddnowpayments_disable_billing($require_billing) {
    global $gateway, $pmpro_requirebilling;

    if ($gateway === 'nowpayments') {
        $pmpro_requirebilling = false;  // Force it globally here
        error_log('Billing requirement set to false for NowPayments.');
        return false;
    }

    return $require_billing;
}

add_filter('pmpro_require_billing', 'pmproaddnowpayments_disable_billing', 50); 

function pmproaddnowpayments_set_gateway() {
    global $gateway;

    // Explicitly retrieve the selected gateway in case it's not set
    if (!isset($gateway) || empty($gateway)) {
        $gateway = pmpro_getOption("gateway"); // Or another way to retrieve the selected gateway
        error_log('Gateway not previously set, retrieved: ' . $gateway);
error_log('Price passed to NowPayments: ' . $amount_to_pay);
error_log('NowPayments data sent: ' . print_r($nowpayments_request, true));

    }
}
add_action('pmpro_checkout_before_processing', 'pmproaddnowpayments_set_gateway');


// Force NowPayments gateway to process payment (bypass billing requirement)
function pmproaddnowpayments_checkout_display() {
    global $gateway, $pmpro_requirebilling;

    error_log('pmproaddnowpayments_checkout_display hook fired, gateway: ' . $gateway);

    if ($gateway === 'nowpayments') {
        // Force billing to be false here just before rendering checkout
        $pmpro_requirebilling = false;
        error_log('Billing requirement forced to false during checkout display for NowPayments.');

        ?>
        <fieldset id="pmpro_payment_method" class="<?php echo esc_attr(pmpro_get_element_class('pmpro_form_fieldset', 'pmpro_payment_method')); ?>">
            <div class="<?php echo esc_attr(pmpro_get_element_class('pmpro_card')); ?>">
                <div class="<?php echo esc_attr(pmpro_get_element_class('pmpro_card_content')); ?>">
                    <legend class="<?php echo esc_attr(pmpro_get_element_class('pmpro_form_legend')); ?>">
                        <h2 class="<?php echo esc_attr(pmpro_get_element_class('pmpro_form_heading pmpro_font-large')); ?>">
                            <?php esc_html_e('Cryptocurrency Payment via NowPayments', 'pmpro-add-nowpayments'); ?>
                        </h2>
                    </legend>
                    <p><?php esc_html_e('You will be redirected to NowPayments to complete the payment.', 'pmpro-add-nowpayments'); ?></p>
                </div>
            </div>
        </fieldset>
        <?php
    }
}
add_action('pmpro_checkout_boxes', 'pmproaddnowpayments_checkout_display', 10);


// Process the payment with NowPayments
function pmproaddnowpayments_process_payment($order) {
    global $gateway;
    error_log('Processing payment through NowPayments, gateway: ' . $gateway);

    if ($gateway === 'nowpayments') {
        error_log('NowPayments gateway detected, processing...');

        // Check if the order has a valid ID and total
        if (!$order->id) {
            $order->code = $order->getRandomCode();  // Generate a new code
            $order->saveOrder();  // Save the new order
            error_log('Created new order with ID: ' . $order->id);
        }

        // Validate total
        if ($order->total == 0) {
            $order->total = pmpro_calculate_membership_cost($order->membership_id);
            error_log('Calculated Membership Cost: ' . $order->total);
        }

        // Save again if necessary
        if ($order->id > 0) {
            error_log('Order is now valid and being processed. ID: ' . $order->id);

        // NowPayments API credentials
        $options = get_option('pmpro_add_nowpayments_options');
        $api_key = isset($options['api_key']) ? $options['api_key'] : '';
        $sandbox_mode = isset($options['sandbox_mode']) ? (bool) $options['sandbox_mode'] : false;
        $webhook_url = isset($options['webhook_url']) ? $options['webhook_url'] : '';
error_log('NowPayments API Response: ' . print_r($response, true));


        if (empty($api_key)) {
            error_log('NowPayments API Key is missing.');
            return;
        }

        $endpoint = $sandbox_mode ? 'https://api-sandbox.nowpayments.io/v1/payment' : 'https://api.nowpayments.io/v1/payment';

        // Prepare the request body
        $body = array(
            'price_amount' => $order->total,
            'price_currency' => $order->currency,
            'pay_currency' => 'xmr',
            'ipn_callback_url' => $webhook_url,
            'order_id' => $order->id,
            'order_description' => 'Membership Payment',
        );

        error_log('Request Body: ' . json_encode($body));

$response = wp_remote_post($endpoint, array(
    'body' => json_encode($body),
    'headers' => array(
        'Content-Type' => 'application/json',
        'x-api-key' => $api_key
    ),
));

error_log('Response status: ' . wp_remote_retrieve_response_code($response));
error_log('Response body: ' . wp_remote_retrieve_body($response));

if (is_wp_error($response)) {
    error_log('Error response from NowPayments: ' . $response->get_error_message());
    return false;
}

        $data = json_decode(wp_remote_retrieve_body($response), true);
        error_log('API Response: ' . print_r($data, true));

if (isset($data['payment_url'])) {
    error_log('Redirecting to NowPayments: ' . $data['payment_url']);
    wp_redirect($data['payment_url']);  // Redirect to NowPayments
    exit;  // Ensure script stops here after redirect
} else {
    error_log('Failed to retrieve payment URL from NowPayments.');
    return false;
}

    } else {
        error_log('Not NowPayments gateway, skipping.');
    }
}
add_action('pmpro_checkout_order', 'pmproaddnowpayments_process_payment', 10);
    error_log('pmpro_checkout_order Hook Fired');
}

// Add IPN handler to WordPress
add_action('init', 'pmproaddnowpayments_handle_ipn');

function pmproaddnowpayments_handle_ipn() {
    if (isset($_GET['action']) && $_GET['action'] === 'nowpayments_ipn') {
        error_log('Received IPN handler request');
        $payload = file_get_contents('php://input');
        error_log('Raw payload: ' . $payload);
        $data = json_decode($payload, true);
        error_log('Decoded data: ' . print_r($data, true));
        // Get raw POST data
        $payload = file_get_contents('php://input');
        error_log('Raw payload: ' . $payload);

        // Check if payload is empty
        if (empty($payload)) {
            error_log('Received empty payload');
            http_response_code(400); // Bad Request
            exit();
        }

        // Decode JSON payload
        $data = json_decode($payload, true);
        if (json_last_error() !== JSON_ERROR_NONE) {
            error_log('JSON decode error: ' . json_last_error_msg());
            http_response_code(400); // Bad Request
            exit();
        }

        // Log headers for debugging
        $headers = getallheaders();
        error_log('Headers: ' . print_r($headers, true));

        // Get secret and signature from headers
        $options = get_option('pmpro_add_nowpayments_options');
        $secret = isset($options['ipn_token']) ? $options['ipn_token'] : '';
        $signature = isset($_SERVER['HTTP_X_NOWPAYMENTS_SIG']) ? $_SERVER['HTTP_X_NOWPAYMENTS_SIG'] : '';

        // Log received signature
        error_log('Received signature: ' . $signature);

        // Sort parameters and generate the expected signature
        ksort($data);
        $sorted_request_json = json_encode($data);
        $calculated_signature = hash_hmac('sha512', $sorted_request_json, $secret);
        error_log('Calculated signature: ' . $calculated_signature);

        // Verify the IPN request
        if ($calculated_signature === $signature) {
            if (isset($data['status']) && $data['status'] === 'paid') {
                $order_id = $data['order_id'];

                // Fetch order and update status
                $order = new MemberOrder($order_id);
                if ($order) {
                    $order->status = 'success';
                    $order->saveOrder();

                    // Update membership level
                    pmpro_changeMembershipLevel($order->membership_id, $order->user_id);
                    error_log('Order marked as success: ' . $order_id);
                } else {
                    error_log('Order not found: ' . $order_id);   
                }
            } else {
                error_log('Invalid IPN status: ' . print_r($data, true));
            }
        } else {
            error_log('IPN signature verification failed');
        }

        // Send acknowledgment
        http_response_code(200);
        exit();
    }
}

// Add menu item for plugin settings
function pmpro_add_nowpayments_menu() {
    add_options_page(
        'NowPayments Settings',
        'NowPayments',
        'manage_options',
        'pmpro-add-nowpayments',
        'pmpro_add_nowpayments_settings_page'
    );
}
add_action('admin_menu', 'pmpro_add_nowpayments_menu');

// Display settings page
function pmpro_add_nowpayments_settings_page() {
    ?>
    <div class="wrap">
        <h1>NowPayments Settings</h1>
        <form method="post" action="options.php">
            <?php
            settings_fields('pmpro_add_nowpayments_options');
            do_settings_sections('pmpro-add-nowpayments');
            submit_button();
            ?>
        </form>
    </div>
    <?php
}

// Register settings
function pmpro_add_nowpayments_settings_init() {
    register_setting('pmpro_add_nowpayments_options', 'pmpro_add_nowpayments_options');

    add_settings_section(
        'pmpro_add_nowpayments_section',
        'NowPayments Payment Settings',
        null,
        'pmpro-add-nowpayments'
    );

    add_settings_field(
        'pmpro_add_nowpayments_api_key',
        'NowPayments API Key',
        'pmpro_add_nowpayments_api_key_field',
        'pmpro-add-nowpayments',
        'pmpro_add_nowpayments_section'
    );

    add_settings_field(
        'pmpro_add_nowpayments_ipn_token',
        'NowPayments IPN Token',
        'pmpro_add_nowpayments_ipn_token_field',
        'pmpro-add-nowpayments',
        'pmpro_add_nowpayments_section'
    );

    add_settings_field(
        'pmpro_add_nowpayments_webhook_url',
        'NowPayments Webhook URL',
        'pmpro_add_nowpayments_webhook_url_field',
        'pmpro-add-nowpayments',
        'pmpro_add_nowpayments_section'
    );
}
add_action('admin_init', 'pmpro_add_nowpayments_settings_init');

// Settings fields callback functions
function pmpro_add_nowpayments_api_key_field() {
    $options = get_option('pmpro_add_nowpayments_options');
    ?>
    <input type="text" name="pmpro_add_nowpayments_options[api_key]" value="<?php echo isset($options['api_key']) ? esc_attr($options['api_key']) : ''; ?>">
    <?php
}

function pmpro_add_nowpayments_ipn_token_field() {
    $options = get_option('pmpro_add_nowpayments_options');
    ?>
    <input type="text" name="pmpro_add_nowpayments_options[ipn_token]" value="<?php echo isset($options['ipn_token']) ? esc_attr($options['ipn_token']) : ''; ?>">
    <?php
}

function pmpro_add_nowpayments_webhook_url_field() {
    $options = get_option('pmpro_add_nowpayments_options');
    ?>
    <input type="text" name="pmpro_add_nowpayments_options[webhook_url]" value="<?php echo isset($options['webhook_url']) ? esc_attr($options['webhook_url']) : ''; ?>">
    <?php
}

?>