WordPress: Twitter Card

gga-twitter-card.php

<?php
/* 
Plugin Name: GGA Twitter Card
Description: Adds Twitter card meta tags to the header 
Author: @GunGeekATX
*/

add_action('wp_head', 'gga_twitter_card_wp_head');
function gga_twitter_card_wp_head() {

  $html[] = "<!-- GGA Twitter Card -->";
	$card_type = 'summary';
	$is_image = false;
	$url = '';
	$title = '';

	$url = is_attachment() || is_single() ? get_permalink() :  home_url();
	

	if (is_attachment() ) {

		$title = get_the_title();
		if (has_excerpt())
			$description = get_the_excerpt();

		$attachment = wp_get_attachment_image_src(get_the_id(), 'full');
		$is_image = wp_attachment_is_image(get_the_id());
		if ($is_image)
			$card_type = 'photo';

	} else if (is_single()) {

		$title = get_the_title() . ' | ' . get_bloginfo('name');
		if (has_excerpt())
			$description = get_the_excerpt();

		$thumbnail_id = get_post_thumbnail_id();
		if ($thumbnail_id) 
			$attachment = wp_get_attachment_image_src($thumbnail_id);
		else {
			// see if we have any attachments, if so, grab the first one

			$attachments = get_children(array( 
				    'post_parent' => get_the_id(),
				    'post_type'   => 'attachment', 
				    'numberposts' => 1,
				    'post_status' => 'any'
				));

			

			if ($attachments && count($attachments) > 0) {
				foreach ($attachments as $att) 
					$attachment = wp_get_attachment_image_src($att->ID);
			}
			
		}



	} else {
		$title = get_bloginfo('name', 'display');
		$description = get_bloginfo( 'description' );
	}


	$html[] = "<meta name=\"twitter:card\" content=\"{$card_type}\" />";
	$html[] = "<meta name=\"twitter:title\" content=\"" . esc_attr($title) . "\" />";
	
	if (isset($description) && !empty($description))
		$html[] = "<meta name=\"twitter:description\" content=\"" . esc_attr($description) . "\" />";

	$html[] = "<meta name=\"twitter:url\" content=\"{$url}\" />";

	if ($attachment && $attachment !== false) {
		$html[] = "<meta name=\"twitter:image\" content=\"" . $attachment[0] . "\" />";
		if ($is_image) {
			$html[] = "<meta name=\"twitter:image:width\" content=\"{$attachment[1]}\">";
			$html[] = "<meta name=\"twitter:image:height\" content=\"{$attachment[2]}\">";
		}
	}


	$html[] = "<!-- GGA Twitter Card end -->";

	foreach ($html as $h)
		echo $h . "\n";

}