<?php

/* Twitter Cards
 *
 * Hooks onto the Open Graph protocol and extends it by adding only the tags
 * we need for twitter cards.
 *
 * @see /wp-content/blog-plugins/open-graph.php
 * @see https://dev.twitter.com/docs/cards
 */
function wpcom_twitter_cards_tags( $og_tags ) {
	global $post;

	if ( apply_filters( 'jetpack_disable_twitter_cards', false ) )
		return $og_tags;

	/*
	 * These tags apply to any page (home, archives, etc)
	 */

	$og_tags['twitter:site'] = ( defined('IS_WPCOM') && IS_WPCOM ) ? '@wordpressdotcom' : '@jetpack';

	if ( ! is_singular() || ! empty( $og_tags['twitter:card'] ) )
		return $og_tags;

	/*
	 * The following tags only apply to single pages.
	 */

	$card_type = 'summary';

	// Try to give priority to featured images
	if ( class_exists('Jetpack_PostImages') ) {
		$featured = Jetpack_PostImages::from_thumbnail( $post->ID, 240, 240 );
		if ( !empty( $featured ) && count( $featured ) > 0 ) {
			if ( (int) $featured[0]['src_width'] >= 280 && (int) $featured[0]['src_height'] >= 150 ) {
				$card_type = 'summary_large_image';
				$og_tags['twitter:image:src'] = add_query_arg( 'w', 640, $featured[0]['src'] );
			} else {
				$og_tags['twitter:image'] = add_query_arg( 'w', 240, $featured[0]['src'] );
			}
		}
	}

	// Only proceed with media analysis if a featured image has not superseded it already.
	if ( empty( $og_tags['twitter:image'] ) && empty( $og_tags['twitter:image:src'] ) ) {
		if ( ! class_exists( 'Jetpack_Media_Summary' ) && defined('IS_WPCOM') && IS_WPCOM )
			include WP_CONTENT_DIR . '/lib/class.wpcom-media-summary.php';

		// Test again, class should already be auto-loaded in Jetpack.
		// If not, skip extra media analysis and stick with a summary card
		if ( class_exists( 'Jetpack_Media_Summary' ) ) {
			$extract = Jetpack_Media_Summary::get( $post->ID );

			if ( 'gallery' == $extract['type'] ) {
				list( $og_tags, $card_type ) = wpcom_twitter_cards_define_type_based_on_image_count( $og_tags, $extract );
			} else if ( 'video' == $extract['type'] ) {
				// Leave as summary, but with large pict of poster frame (we know those comply to Twitter's size requirements)
				$card_type = 'summary_large_image';
				$og_tags['twitter:image:src'] = add_query_arg( 'w', 640, $extract['image'] );
			} else {
				list( $og_tags, $card_type ) = wpcom_twitter_cards_define_type_based_on_image_count( $og_tags, $extract );
			}
		}
	}

	$og_tags['twitter:card'] = $card_type;

	// If we have information on the author/creator, then include that as well
	if ( ! empty( $post ) && ! empty( $post->post_author ) ) {
		$handle = apply_filters( 'jetpack_sharing_twitter_via', '', $post->ID );
		if ( !empty( $handle ) && 'wordpressdotcom' != $handle )
			$og_tags['twitter:creator'] = '@' . $handle;
	}

	// Make sure we have a description for Twitter, their validator isn't happy without some content (single space not valid).
	if ( ! isset( $og_tags['og:description'] ) || '' == trim( $og_tags['og:description'] ) ) { // empty( trim( $og_tags['og:description'] ) ) isn't valid php
		$has_creator = ( !empty($og_tags['twitter:creator']) && '@wordpressdotcom' != $og_tags['twitter:creator'] ) ? true : false;
		if ( 'photo' == $card_type )
			$og_tags['twitter:description'] = ( $has_creator ) ? sprintf( __('Photo post by %s.', 'jetpack'), $og_tags['twitter:creator'] ) : __('Photo post.', 'jetpack');
		else if ( !empty( $extract ) && 'video' == $extract['type'] ) // use $extract['type'] since $card_type is 'summary' for video posts
			$og_tags['twitter:description'] = ( $has_creator ) ? sprintf( __('Video post by %s.', 'jetpack'), $og_tags['twitter:creator'] ) : __('Video post.', 'jetpack');
		else if ( 'gallery' == $card_type )
			$og_tags['twitter:description'] = ( $has_creator ) ? sprintf( __('Gallery post by %s.', 'jetpack'), $og_tags['twitter:creator'] ) : __('Gallery post.', 'jetpack');
		else
			$og_tags['twitter:description'] = ( $has_creator ) ? sprintf( __('New post by %s.', 'jetpack'), $og_tags['twitter:creator'] ) : __('New post.', 'jetpack');
	}

	return $og_tags;
}

function wpcom_twitter_cards_define_type_based_on_image_count( $og_tags, $extract ) {
	$card_type = 'summary';
	$img_count = $extract['count']['image'];

	if ( empty( $img_count ) ) {
		// No images, use Blavatar as a thumbnail for the summary type.
		if ( function_exists('blavatar_domain') ) {
			$blavatar_domain = blavatar_domain(site_url());
			if ( blavatar_exists( $blavatar_domain ) )
				$og_tags['twitter:image'] = blavatar_url( $blavatar_domain, 'img', 240);
		}
		// Not falling back on Gravatar, because there's no way to know if we end up with an auto-generated one.
	} else if  ( 1 == $img_count && ( 'image' == $extract['type'] || 'gallery' == $extract['type'] ) ) {
		// 1 image = photo
		// Test for $extract['type'] to limit to image and gallery, so we don't send a potential fallback image like a Gravatar as a photo post.
		$card_type = 'photo';
		$og_tags['twitter:image'] = add_query_arg( 'w', 1400, ( empty( $extract['images'] ) ) ? $extract['image'] : $extract['images'][0]['url'] );
	} else if ( $img_count <= 3 ) {
		// 2-3 images = summary with small thumbnail
		$og_tags['twitter:image'] = add_query_arg( 'w', 240, ( empty( $extract['images'] ) ) ? $extract['image'] : $extract['images'][0]['url'] );
	} else if ( $img_count >= 4 ) {
		// >= 4 images = gallery
		$card_type = 'gallery';
		$og_tags = wpcom_twitter_cards_gallery( $extract, $og_tags );
	}

	return array( $og_tags, $card_type );
}

function wpcom_twitter_cards_gallery( $extract, $og_tags ) {
	foreach( $extract['images'] as $key => $value ) {
		if ( $key > 3 )
			break; // Can only send a max of 4 picts (https://dev.twitter.com/docs/cards/types/gallery-card)
		$og_tags[ 'twitter:image' . $key ] = add_query_arg( 'w', 640, $value['url'] );
	}
	return $og_tags;
}

add_filter( 'jetpack_open_graph_tags', 'wpcom_twitter_cards_tags' );

function wpcom_twitter_cards_output( $og_tag ) {
	return ( false !== strpos( $og_tag, 'twitter:' ) ) ? preg_replace( '/property="([^"]+)"/', 'name="\1"', $og_tag ) : $og_tag;
}

add_filter( 'jetpack_open_graph_output', 'wpcom_twitter_cards_output' );