WordPress Page Template to build a feed of your Google+ stream

google-plus-feed.php

<?php
/**
 * Template Name: Google+ Feed
 */


/**
 * A WordPress page template for a Google+ feed.
 *
 * @author Dominik Schilling
 * @license GPLv2
 * @link http://wpgrafie.de/567/
 *
 * @version 0.2
 */
class Google_Plus_Feed {
	/**
	 * Google+ API Key.
	 * See https://code.google.com/apis/console/
	 *
	 * @since 0.1
	 *
	 * @var string
	 */
	private $api_key = '';

	/**
	 * Google+ User ID.
	 *
	 * @since 0.1
	 *
	 * @var string
	 */
	private $user_id = '';
	
	/**
	 * Custom settings.
	 * See $this->set_settings()
	 *
	 * @since 0.1
	 *
	 * @var array
	 */
	private $settings = array();
	
	/**
	 * Don't change the lines after these
	 * if you don't know what you do.
	 */

	/**
	 * Google+ activities.
	 *
	 * @since 0.1
	 *
	 * @var mixed
	 */
	private $activities;

	/**
	 * Current queried object.
	 *
	 * @since 0.1
	 *
	 * @var object
	 */
	private $curr_obj;

	/**
	 * Construct.
	 *
	 * @since 0.1
	 *
	 * @return void
	 */
	function __construct() {
		if( empty( $this->curr_obj ) )
			$this->curr_obj = get_queried_object();

		if( ! $this->get_api_key() || ! $this->get_user_id() )
			wp_die( 'Not configured!' );

		$this->set_settings();

		$this->activities = $this->build_activities();

		if ( empty( $this->activities ) )
			wp_die( 'Please load again.' );

		$this->feed_output();
	}

	/**
	 * Get the API key from
	 *    post custom field (gplusfeed_api_key)
	 * or
	 *    $this->api_key
	 *
	 * @since 0.1
	 *
	 * @return string|bool Key on success, false if key is missing.
	 */
	function get_api_key() {
		$api_key = get_post_meta( $this->curr_obj->ID, 'gplusfeed_api_key', true );

		if ( ! empty( $api_key ) )
			return $api_key;
		else if( ! empty( $this->api_key ) )
			return $this->api_key;
		else
			return false;
	}

	/**
	 * Get the user id from
	 *    post custom field (gplus_feed_user_id)
	 * or
	 *    $this->user_id
	 *
	 * @since 0.1
	 *
	 * @return string|bool Key on success, false if key is missing.
	 */
	function get_user_id() {
		$user_id = get_post_meta( $this->curr_obj->ID, 'gplus_feed_user_id', true );

		if ( ! empty( $user_id ) )
			return $user_id;
		else if( ! empty( $this->user_id ) )
			return $this->user_id;
		else
			return false;
	}

	/**
	 * Set custom feed settings.
	 *
	 *  - limit: How many activities should be displayed in feed
	 *  - cache_time: How long the feed should be cached
	 *  - language: The language of the feed
	 *  - update_period: See http://web.resource.org/rss/1.0/modules/syndication/
	 *  - update_frequency: See http://web.resource.org/rss/1.0/modules/syndication/
	 *
	 * @since 0.1
	 *
	 * @return array Settings saved in an array.
	 */
	function set_settings() {
		$this->settings = wp_parse_args(
			array(
				'limit' => 10,
				'cache_time' => 300,
				'language' => 'de',
				'update_period' => 'hourly',
				'update_frequency' => 1
			),
			$this->settings
		);
	}

	/**
	 * Get the Google+ API link.
	 * See https://developers.google.com/+/api/latest/activities/list
	 *
	 * @since 0.1
	 *
	 * @return string URL of the Google+ API.
	 */
	function get_api_link() {
		$api_link = add_query_arg(
			array(
				'alt' => 'json',
				'maxResults' => $this->settings['limit'],
				'pp' => 1,
				'key' => $this->get_api_key()
			),
			sprintf( 'https://www.googleapis.com/plus/v1/people/%s/activities/public', $this->get_user_id() )
		);

		return esc_url_raw( $api_link );
	}

	/**
	 * Build the activity stream and save it in a transient.
	 *
	 * @since 0.1
	 *
	 * @return string|bool Activities in XML format or false on error.
	 */
	function build_activities() {
		$dev = true;
		if ( false !== ( $activities = get_transient( $this->get_cache_key() ) ) && ! $dev )
			return $activities;

		$activities = $this->get_activities();

		if ( is_wp_error( $activities ) )
			return false;

		$activities = $this->render_activities( $activities );

		if ( empty( $activities ) )
			return false;

		// Cache activities
		set_transient( $this->get_cache_key(), $activities, $this->settings['cache_time'] );

		return $activities;
	}

	/**
	 * Build an individual cache key.
	 * Based on settings, user id and API key.
	 *
	 * @since 0.1
	 *
	 * @return string The cache key.
	 */
	function get_cache_key() {
		return 'gplus_feed_' . md5(
			implode( '|', $this->settings )
			. $this->get_user_id()
			. $this->get_api_key()
		);
	}

	/**
	 * Get the activities from Google+ API.
	 *
	 * @since 0.1
	 *
	 * @return array|WP_Error API result in an array or WP_Error on API/HTTP error.
	 */
	function get_activities() {
		$result = wp_remote_retrieve_body(
			wp_remote_get(
				$this->get_api_link()
			)
		);

		if ( ! empty( $result ) ) {
			$result = (array) json_decode( $result );

			if ( empty ( $results->error ) )
				return $result;
			else
				return new WP_Error( 'api_error', 'API ERROR', $results->error );
		} else {
			return new WP_Error( 'http_error', 'HTTP ERROR');
		}
	}

	/**
	 * Render the activities and return them in XML format.
	 *
	 * @since 0.1
	 *
	 * @param array $activities
	 * @return array Rendered activity items for feed.
	 */
	function render_activities( $activities ) {
		$feed = array();

		foreach( $activities['items'] as $item => $data ) {
			if ( ! preg_match('/^<b\b[^>]*>(.*?)<\/b>/i', $data->object->content, $matches ) ) {
				$title = $data->title;
				$content = $data->object->content;
			} else {
				$title = strip_tags( $matches[1] );
				$content = str_replace( $matches[0] . '<br /><br />', '', $data->object->content );
			}

			if ( ! empty( $data->object->attachments ) )
				$content .= $this->_render_activity_attachments( $data->object->attachments );

			$feed[$item] = "
<item>
	<title>{$title}</title>
	<link>{$data->url}</link>
	<pubDate>" . mysql2date( 'D, d M Y H:i:s +0000', $data->published, false ) . "</pubDate>
	<dc:creator>{$data->actor->displayName}</dc:creator>
	<guid isPermaLink=\"false\">{$data->url}</guid>

	<description><![CDATA[" . wp_trim_words( $content, 20 ) . "]]></description>
	<content:encoded><![CDATA[{$content}]]></content:encoded>

	<slash:comments>{$data->object->replies->totalItems}</slash:comments>
</item>
";
		}

		return $feed;
	}

	/**
	 * Handle activity attachments, like video, photo and links (articles).
	 *
	 * @since 0.2
	 *
	 * @param array $attachments
	 * @return string Attachments in HTML format.
	 */
	function _render_activity_attachments( $attachments ) {
		$articles = $photos = $videos = array();

		foreach ( $attachments as $attachment => $meta ) {
			switch ( $meta->objectType ) {
				case 'article' :
					$host = @parse_url( $meta->url, PHP_URL_HOST );
					$articles[] = sprintf(
						'%s<a href="%s" title="%s">%s</a>',
						empty( $host ) ? '' : $host . ' – ',
						esc_url( $meta->url ),
						empty( $meta->content ) ? '' : esc_attr( $meta->content ),
						empty( $meta->displayName ) ? '' : $meta->displayName
					);
					break;
				case 'photo' :
					$photos[] = sprintf(
						'%s<img src="%s" height="%s" width="%s" alt="%s" title="%s" style="margin:5px;max-width:250px;height:auto" />%s',
						empty( $meta->fullImage->url ) ? '' : '<a href="' . esc_url( $meta->fullImage->url ) . '">',
						esc_url( $meta->image->url ),
						empty( $meta->image->height ) ? '' : esc_attr( $meta->image->height ),
						empty( $meta->image->width ) ? '' : esc_attr( $meta->image->width ),
						empty( $meta->displayName ) ? '' : $meta->displayName,
						empty( $meta->displayName ) ? '' : $meta->displayName,
						empty( $meta->fullImage->url ) ? '' : '</a>'
					);
					break;
				case 'video' :
					$videos[] = sprintf(
						'<a href="%s"><img src="%s" height="%s" width="%s" alt="%s" title="%s" style="margin:5px;max-width:250px;height:auto" /></a>',
						esc_url( $meta->url ),
						esc_url( $meta->image->url ),
						empty( $meta->image->height ) ? '' : esc_attr( $meta->image->height ),
						empty( $meta->image->width ) ? '' : esc_attr( $meta->image->width ),
						empty( $meta->displayName ) ? '' : $meta->displayName,
						empty( $meta->displayName ) ? '' : $meta->displayName
					);
					break;
			}
		}
		
		$content = '';
		$_html = '<div style="display:table-row"><div style="display:table-cell;vertical-align:top;padding:0 10px 0 0"><b>%s:</b></div>';
		if ( ! empty( $articles ) ) {
			$articles = implode( '<br />', $articles );
			$content .= sprintf(
				$_html,
				__( 'Links' )
			);
			$content .= sprintf(
				'<div style="display:table-cell">%s</div></div>',
				$articles
			);
		}
		
		if ( ! empty( $photos ) ) {
			$photos = implode( '', $photos );
			$content .= sprintf(
				$_html,
				__( 'Images' )
			);
			$content .= sprintf(
				'<div style="display:table-cell">%s</div></div>',
				$photos
			);
		}
		
		if ( ! empty( $videos ) ) {
			$videos = implode( '', $videos );
			$content .= sprintf(
				$_html,
				__( 'Video' )
			);
			$content .= sprintf(
				'<div style="display:table-cell">%s</div></div>',
				$videos
			);
		}
		
		if ( ! empty( $content ) )
			$content = sprintf(
				'<br /><br /><h4>%s</h4><div style="display:table">%s</div>',
				__( 'Images and Attachments' ),
				$content
			);

		return $content;
	}

	/**
	 * Build the feed output.
	 *
	 * @since 0.1
	 *
	 * @return void
	 */
	function feed_output() {
		$this->get_rss_header();
		$this->get_rss_content();
		$this->get_rss_footer();
	}

	/**
	 * Retrieve information about the feed.
	 *
	 * @since 0.1
	 *
	 * @param string $show Feed info to retrieve.
	 * @param bool $echo Return or print the info. Default: true.
	 * @return string Feed info.
	 */
	function get_feed_info( $show, $echo = true ) {
		switch ( $show ) {
			case 'title' :
				$output = apply_filters( 'the_title_rss', $this->curr_obj->post_title ) ;
				break;
			case 'self' :
				$host = @parse_url( home_url() );
				$host = $host['host'];
				$output = esc_url(
					( is_ssl() ? 'https' : 'http' ) . '://'
					. $host
					. stripslashes( $_SERVER['REQUEST_URI'] )
				);
				break;
			case 'link' :
				$output = esc_url( sprintf( 'https://plus.google.com/%d/', $this->get_user_id() ) );
				break;
			case 'desc' :
				$output = apply_filters( 'the_title_rss', $this->curr_obj->post_content );
				break;
			case 'time' :
				$timeout = get_option( '_transient_timeout_' . $this->get_cache_key() );
				if ( $timeout === false )
					$time = time();
				else
					$time = $timeout - $this->settings['cache_time'];
				$output = date( 'D, d M Y H:i:s +0000', $time );
				break;
			case 'language' :
				$output = $this->settings['language'];
				break;
			case 'update_period' :
				$output = $this->settings['update_period'];
				break;
			case 'update_frequency' :
				$output = $this->settings['update_frequency'];
				break;
		}

		if( ! $echo )
			return $output;

		echo $output;
	}

	/**
	 * Print the feed header.
	 *
	 * @since 0.1
	 *
	 * @return void
	 */
	function get_rss_header() {
		header( 'Content-Type: text/xml; charset=UTF-8', true );
		echo '<?xml version="1.0" encoding="UTF-8"?'.'>';
	?>
<rss version="2.0"
xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:wfw="http://wellformedweb.org/CommentAPI/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
>
<channel>
	<title><?php $this->get_feed_info( 'title' ); ?></title>
	<atom:link href="<?php $this->get_feed_info( 'self' ); ?>" rel="self" type="application/rss+xml" />
	<link><?php $this->get_feed_info( 'link' ); ?></link>
	<description><?php $this->get_feed_info( 'desc' ); ?></description>
	<lastBuildDate><?php $this->get_feed_info( 'time' ); ?></lastBuildDate>
	<language><?php $this->get_feed_info( 'language' ); ?></language>
	<sy:updatePeriod><?php $this->get_feed_info( 'update_period' ); ?></sy:updatePeriod>
	<sy:updateFrequency><?php $this->get_feed_info( 'update_frequency' ); ?></sy:updateFrequency>
	<?php
	}

	/**
	 * Print the feed content/activities.
	 *
	 * @since 0.1
	 *
	 * @return void
	 */
	function get_rss_content() {
		foreach( $this->activities as $item )
			echo $item;
	}

	/**
	 * Print the feed footer.
	 *
	 * @since 0.1
	 *
	 * @return void
	 */
	function get_rss_footer() {
	?>
</channel>
</rss>
	<?php
	}
}

// Init
$feed = new Google_Plus_Feed();