redirect-processor.php

<?php
/**
 * On form submit, do a redirect to a diffrent site, then complete submission
 */
add_action('caldera_forms_submit_process_start',  function (
	$form,
	$referrer,
	$process_id
) {
	//If we have a already done redirect, do nothing
	if (isset($_GET['cf_tp'])) {
		return;
	}

	//Get current URL
	$url = caldera_forms_build_url($referrer);
	//Append transient ID
	$url = add_query_arg('cf_tp', $process_id, $url);

	//Set CF to redirect to other site
	add_filter('caldera_forms_redirect_url_complete', function () use ($url, $process_id) {
		//Save transdata
		//This should be automatic. See: https://github.com/CalderaWP/Caldera-Forms/issues/3312
		global $transdata;
		Caldera_Forms_Transient::set_transient($process_id, $transdata, 5 * 60);

		//create redirect URL.
		return 'http://localhost:8080/?redirect=' . urlencode($url);
	}, 9999);
}, 10, 3);

//@see https://github.com/CalderaWP/Caldera-Forms/issues/3313
if (!function_exists('caldera_forms_build_url')) {
	function caldera_forms_build_url(array $parts)
	{
		if (function_exists('http_build_url')) {
			return http_build_url($parts);
		}
		return add_query_arg(
			$parts['query'],
			(isset($parts['scheme']) ? "{$parts['scheme']}:" : '')
				. ((isset($parts['user']) || isset($parts['host'])) ? '//' : '')
				. (isset($parts['user']) ? "{$parts['user']}" : '')
				. (isset($parts['pass']) ? ":{$parts['pass']}" : '')
				. (isset($parts['user']) ? '@' : '')
				. (isset($parts['host']) ? "{$parts['host']}" : '')
				. (isset($parts['port']) ? ":{$parts['port']}" : '')
				. (isset($parts['path']) ? "{$parts['path']}" : '')
				. (isset($parts['fragment']) ? "#{$parts['fragment']}" : '')
		);
	}
}