Payfast split payments - woocommerce

Question

I need to add "something" to the Woocommerce payfast plugin to enable it to process split payments, as per the Payfast website it would look like this:
{ "split_payment" : { "merchant_id":10000105, "percentage":10, "amount":500, "min":100, "max":100000 } }
and it is submitted by form like this:
<input type="hidden" name="setup" value='{ "split_payment" : {
"merchant_id":10000105,
"percentage":10,
"min":100,
"max":100000}}' >
I have looked at the class-wc-gateway-payfast.php file and cannot see where this could be "injected" and I have looked for the html form and cannot find that either .... My gut tells me this is simple yet I cannot get my head around it :
The Payfast link giving me the instructions can be found here (in case I am not reading it properly) : https://developers.payfast.co.za/documentation/?html#direct-request-method
Am I not correct in my thinking that it must go here :
/**
* Generate the PayFast button link.
*
* #since 1.0.0
*/
public function generate_payfast_form( $order_id ) {
$order = wc_get_order( $order_id );
// Construct variables for post
$this->data_to_send = array(
// Merchant details
'merchant_id' => $this->merchant_id,
'merchant_key' => $this->merchant_key,
'return_url' => $this->get_return_url( $order ),
'cancel_url' => $order->get_cancel_order_url(),
'notify_url' => $this->response_url,
// Billing details
'name_first' => self::get_order_prop( $order, 'billing_first_name' ),
'name_last' => self::get_order_prop( $order, 'billing_last_name' ),
'email_address' => self::get_order_prop( $order, 'billing_email' ),
// Item details
'm_payment_id' => ltrim( $order->get_order_number(), _x( '#', 'hash before order number', 'woocommerce-gateway-payfast' ) ),
'amount' => $order->get_total(),
'item_name' => get_bloginfo( 'name' ) . ' - ' . $order->get_order_number(),
/* translators: 1: blog info name */
'item_description' => sprintf( __( 'New order from %s', 'woocommerce-gateway-payfast' ), get_bloginfo( 'name' ) ),
// Custom strings
'custom_str1' => self::get_order_prop( $order, 'order_key' ),
'custom_str2' => 'WooCommerce/' . WC_VERSION . '; ' . get_site_url(),
'custom_str3' => self::get_order_prop( $order, 'id' ),
'source' => 'WooCommerce-Free-Plugin',
);

Answer 1

The form gets generated based on the associative array. You would have to add the following to the array for split payments:
'setup' => json_encode(['split_payment' => ['merchant_id' => 10000105, 'percentage'=>10, 'min' => 100, 'max' => 100000]]),
The json_encode() function is used to convert the PHP multidimensional array into a JSON object. More information on the json_encode() function can be found here.
The complete array will be as follows:
$this->data_to_send = array(
// Merchant details
'merchant_id' => $this->merchant_id,
'merchant_key' => $this->merchant_key,
'return_url' => $this->get_return_url( $order ),
'cancel_url' => $order->get_cancel_order_url(),
'notify_url' => $this->response_url,
// Billing details
'name_first' => self::get_order_prop( $order, 'billing_first_name' ),
'name_last' => self::get_order_prop( $order, 'billing_last_name' ),
'email_address' => self::get_order_prop( $order, 'billing_email' ),
// Item details
'm_payment_id' => ltrim( $order->get_order_number(), _x( '#', 'hash before order number', 'woocommerce-gateway-payfast' ) ),
'amount' => $order->get_total(),
'item_name' => get_bloginfo( 'name' ) . ' - ' . $order->get_order_number(),
/* translators: 1: blog info name */
'item_description' => sprintf( __( 'New order from %s', 'woocommerce-gateway-payfast' ), get_bloginfo( 'name' ) ),
//Split Payment
'setup' => json_encode(['split_payment' => ['merchant_id' => 10000105, 'percentage'=>10, 'min' => 100, 'max' => 100000]]),
// Custom strings
'custom_str1' => self::get_order_prop( $order, 'order_key' ),
'custom_str2' => 'WooCommerce/' . WC_VERSION . '; ' . get_site_url(),
'custom_str3' => self::get_order_prop( $order, 'id' ),
'source' => 'WooCommerce-Free-Plugin',
);