Add a twitter share button to EDD's purchase confirmation page.

gistfile1.php

<?php

function edd_custom_success_page_share() {
	global $edd_receipt_args, $edd_options;

	$payment   			= get_post( $edd_receipt_args['id'] );
	$meta      			= edd_get_payment_meta( $payment->ID );
	$cart      			= edd_get_payment_meta_cart_details( $payment->ID, true );
	$first_download 		= array_values( $cart );	
	$first_download 		= array_shift( $first_download );
	$name 				= $first_download['name'];

	// make sure a success page has been set in the options and we're on it
	if ( isset( $edd_options['success_page'] ) && is_page( $edd_options['success_page'] ) ) {

		// more than 1 purchase
		if( count($cart) > 1 ) {
			$twitter_message = 'I just snagged ' . $name . ' and other awesome stuff from';
		}
		// only 1 purchase
		else {
			$twitter_message = 'I just snagged ' . $name . ' from';
		}

	?>

		<h2>We really appreciate your support!</h2>
		
		<a href="https://twitter.com/share" class="twitter-share-button" data-count="vertical" data-url="http://sumobi.com" data-text="<?php echo $twitter_message; ?>" data-via="sumobi_" data-related="sumobi_">Share</a>
		<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+'://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js,fjs);}}(document, 'script', 'twitter-wjs');</script>
		
	<?php }
}
add_action( 'edd_payment_receipt_after', 'edd_custom_success_page_share' );