Adding Donation or Surcharge to Payment Gateways

<?php
/*
This snippet will allow you to add a donation text field to your Events Manager Pro booking form, which will then add that amount to the total payment when redirected to PayPal, Stripe or Offline Payment Gateways.

Instructions:

1. in your Forms Editor, create a new field
– label => Donation Amount
– field id => donation_amount
– type => select; then under option you can add the amount per line

2. In your theme functions.php; paste the following snippet or for complete guide you can visit http://wp-events-plugin.com/tutorials/how-to-safely-add-php-code-to-wordpress/

Reference: https://eventsmanagerpro.com/support/questions/donation-option-3/

*/

function my_em_price_adjustments( $EM_Event, $EM_Booking, $post_validation ){
    if( $post_validation ){

        if( empty($EM_Booking->booking_meta['surcharges']) ) $EM_Booking->booking_meta['surcharges'] = array();

        //donation_amount = Field Id from Events > Forms Editor
        $amount = ( !empty($EM_Booking->booking_meta['booking']['donation_amount']) ) ? $EM_Booking->booking_meta['booking']['donation_amount']:1;

        $label = "Test Surcharge";

        $EM_Booking->booking_meta['surcharges'][] = array(
                'name' => $label,
                //'desc' => 'Some type of surcharge description',
                'type' => '#', //numerical discount i.e. $10.00 off
                'amount' => $amount,
                'tax' => 'pre' //discount applied BEFORE taxes have been added, and IS taxable
        );


    }//END - if( $post_validation ){
}
add_action('em_booking_add', 'my_em_price_adjustments', 10, 3);