<?php

add_action( 'edd_post_add_to_cart', 'gvtheme_edd_post_add_to_cart', 10, 2 );

/**
 * Prevent adding more than one of a certain download.
 *
 * If a download is already added, this will overwrite the previous configuration with the new one
 *
 * @since       1.0.0
 * @param       int $download_id The ID of a specific download
 * @param       array $options The options for this downloads
 * @return      void
 */
function gvtheme_edd_post_add_to_cart( $download_id, $options ) {

	$cart = edd_get_cart_contents();

	foreach ( $cart as $key => $item ) {
		if( intval( $download_id ) === intval( $item['id'] ) ) {
			unset( $cart[ $key ] );
		}
	}

	$cart[] = array(
		'id'       => $download_id,
		'options'  => $options,
		'quantity' => 1
	);

	EDD()->session->set( 'edd_cart', $cart );
}